YARRA VALLEY WATER
2007 APPLIANCE STOCK
And
USAGE PATTERNS SURVEY
Authors: Asoka Athuraliya, Kein Gan and
Peter Roberts
May 2008
TABLE OF CONTENTS
EXECUTIVE SUMMARY ....................................................................................................................1
1
INTRODUCTION.........................................................................................................................6
2
METHODOLOGY AND SAMPLING .......................................................................................6
2.1
2.2
2.3
2.4
3
METHODOLOGY .....................................................................................................................6
SAMPLING FRAME. .................................................................................................................7
RECRUITMENT OF SURVEY PARTICIPANTS. ............................................................................8
REPRESENTATIVENESS OF SAMPLE ........................................................................................9
USAGE AND HOUSEHOLD SIZE .......................................................................................... 11
3.1
AVERAGE DAILY USAGE BY HOUSEHOLD SIZE .................................................................... 11
3.2
SUMMER VERSUS WINTER USAGE BY HOUSEHOLD SIZE ...................................................... 12
3.3
MODELLING USAGE WITH HOUSEHOLD SIZE. ...................................................................... 14
3.3.1
Annual Modelled Water Usage per Household .............................................................. 14
3.3.2
Modelling per Capita Usage with Household Size ......................................................... 15
4
SURVEY FINDINGS – INDOOR USE..................................................................................... 16
4.1
SHOWERS ............................................................................................................................. 16
4.1.1
Frequency of Showering ................................................................................................. 16
4.1.2
Shower Duration............................................................................................................. 16
4.1.3
Shower Capacity Flow Rate ........................................................................................... 18
4.1.4
Shower Typical Flow Rate.............................................................................................. 19
4.1.5
Ratio of Typical to Capacity Flow Rate.......................................................................... 20
4.1.6
Time Delay for Hot Water .............................................................................................. 21
4.2
TOILETS ............................................................................................................................... 22
4.2.1
Type of Toilets ................................................................................................................ 22
4.2.2
Toilet Leaks. ................................................................................................................... 23
4.2.3
Toilet Flush Volume........................................................................................................ 24
4.2.4
Frequency of Toilet Use.................................................................................................. 25
4.2.5
Incidence of Double Flushing......................................................................................... 26
4.2.6
Toilet Flush Volume Reduction ...................................................................................... 27
4.3
CLOTHES WASHERS ............................................................................................................. 27
4.3.1
Ownership and Type of Washing Machine ..................................................................... 27
4.3.2
Frequency of Clothes Washer Use.................................................................................. 28
4.3.3
Behavioural Patterns for Clotheswashers ...................................................................... 30
4.3.3.1
4.3.3.2
Clotheswasher Water Level, Load Size and Temperature................................................... 30
Machine Washing versus Hand Washing............................................................................ 32
4.4
DISHWASHERS...................................................................................................................... 33
4.4.1
Dishwasher Ownership and Frequency of Use .............................................................. 33
4.4.2 Behaviour Patterns for Dishwashers ................................................................................... 35
4.5
TAP USE ............................................................................................................................... 36
4.5.1
Hand Basin ..................................................................................................................... 36
4.5.1.1
4.5.1.2
4.5.1.3
4.5.1.4
4.5.2
Kitchen Sink.................................................................................................................... 38
4.5.2.1
4.5.2.2
4.5.2.3
4.5.2.4
4.5.3
Hand Basin Location........................................................................................................... 36
Flow Rate............................................................................................................................ 36
Frequency of Hand Basin Use............................................................................................. 37
Hand Basin Leaks ............................................................................................................... 38
Kitchen Sink Tap Flow Rate ............................................................................................... 38
Hand Washing Dishes......................................................................................................... 39
Cooking............................................................................................................................... 40
Leaks................................................................................................................................... 40
Laundry Trough.............................................................................................................. 40
4.5.3.1
4.5.3.2
Flow Rate............................................................................................................................ 40
Leaks................................................................................................................................... 40
4.6
BATHS .................................................................................................................................. 41
4.6.1
Bath Use by Adults ......................................................................................................... 41
4.6.2
Bath Use by Children...................................................................................................... 42
4.7
EVAPORATIVE AIR CONDITIONERS. ..................................................................................... 42
i
5
SURVEY FINDINGS - OUTDOOR USE ................................................................................. 44
5.1
5.2
5.3
5.3.1
5.3.2
5.4
5.4.1
5.4.2
5.4.3
5.5
5.5.1
5.5.2
5.5.3
5.6
5.6.1
5.6.2
5.6.3
5.7
5.8
5.8.1
5.8.2
5.8.3
5.8.4
5.8.5
5.8.6
5.8.7
WATER RESTRICTIONS ......................................................................................................... 44
PROPERTY TYPES ................................................................................................................. 44
GARDEN CONFIGURATION.................................................................................................... 45
Type of Garden ............................................................................................................... 45
Garden Extent................................................................................................................. 46
GARDEN BEDS...................................................................................................................... 46
Garden Beds - Irrigation Frequency .............................................................................. 46
Garden Beds - Irrigation Duration................................................................................. 48
Garden Beds - Irrigation Methods.................................................................................. 49
VEGETABLE GARDEN ........................................................................................................... 51
Vegetable Garden – Irrigation Frequency ..................................................................... 52
Vegetable Garden – Irrigation Duration........................................................................ 52
Vegetable Garden – Irrigation Methods......................................................................... 53
LAWN ................................................................................................................................... 55
Lawn – Irrigation Frequency.......................................................................................... 55
Lawn – Irrigation Duration ............................................................................................ 56
Lawn – Irrigation Methods............................................................................................. 56
GARDEN SURVIVAL UNDER DROUGHT RESTRICTIONS ......................................................... 57
OTHER GARDEN PRACTICES ................................................................................................. 59
Mulch.............................................................................................................................. 59
Garden Tap Timer .......................................................................................................... 59
Garden Rain Sensor........................................................................................................ 60
Garden Soil Moisture Sensor.......................................................................................... 60
Rainwater Tanks ............................................................................................................. 61
Greywater ....................................................................................................................... 63
Outdoor Swimming Pool................................................................................................. 63
5.8.7.1
5.8.7.2
5.8.7.3
6
Incidence of Swimming Pools............................................................................................. 63
Use of Pool Cover ............................................................................................................... 64
Topping Up Swimming Pools ............................................................................................. 64
APPENDIX A: RECRUITMENT LETTER ............................................................................ 67
7
APPENDIX B: APPLIANCE STOCK & USAGE PATTERNS SURVEY 2007 QUESTIONS......................................................................................................................................... 69
ii
Executive Summary
In order to better manage water resources it is essential to understand both the nature of water
use in the residential sector (behaviours) and the ongoing changes in the types of appliances in
use within households (stock profile). This knowledge is important to Yarra Valley Water for a
number of reasons in particular
− To enable the establishment and maintenance of end use models used to predict
demand,
− To assist the design and evaluation of demand management programs, and
− To inform communications with customers regarding typical and efficient levels of
water use.
The 2007 Appliance Stock and Usage Patterns Survey (ASUPS 2007) gathered extensive data
on both the stock profile of water using appliances and the way in which they are used. The
study involved household visits to 850 homes in Yarra Valley Water’s area and was undertaken
from August to October 2007.
ASUPS 2007 is the third large sample research study of this nature undertaken by Yarra Valley
Water, the prior studies being the Residential Forecasting Study 1999 and the Appliance Stock
and Usage Patterns Survey 2003. All these studies primarily involved respondents estimating
their usage patterns on the basis of recall as opposed to actual measurement over a period of
time.
In order to address the unavoidable discrepancy between how respondents recall their usage
patterns and what are their actual usage patterns Yarra Valley Water has also undertaken two
complementary end use measurement studies namely the Residential End Use Measurement
Study 2004 and the 2005 Evaporative Air Conditioner Study. Whilst providing more accurate
data the sample sizes for such studies are necessarily small given the high cost of collecting
end use measurement data. It is Yarra Valley Water’s intention to undertake additional end use
measurement to complement the ASUPS 2007 in the 2008/09 financial year.
Since the 2003 ASUPS was undertaken it is evident from quarterly billing data that usage both
in and outside the home has decreased substantially1. Whilst the reduction in use outside the
home is primarily the result of drought restrictions2 the usage reduction inside the home has
resulted from voluntary behavioural and appliance change. The findings from ASUPS 2007
provide some valuable insights into how these factors have changed since 2003.
Because the survey was undertaken during a period of drought restrictions some questions
from previous surveys could not be used this time. In particular questions about car washing
frequency and method were abandoned since there was a total ban on this activity for a lengthy
period prior to and during the survey.
Usage billed during the September quarter (ie July to September) primarily reflects indoor usage. Yarra Valley
Water’s average daily usage per residential property declined from 504 litres in the September quarter 2003 to 409
litres in September 2007, a reduction of 19%.
2 ASUPS 2003 was undertaken during a period of Stage 2 water restrictions. Since then Melbourne came out of
restrictions for 18 months before returning to restrictions in September 2006. When ASUPS 2007 was undertaken
Melbourne was in Stage 3a restrictions.
1
1
The survey findings for many usage parameters were generally indicative of a substantial
decrease in water use since the 2003 survey. This outcome should be considered in the light
that the average usage of the ASUPS 2007 sample households in 2006/07 was 6% lower than
the overall Yarra Valley Water average despite the sample having a greater than average
household size (3.0 versus Yarra Valley Water’s overall average of 2.73 persons). Therefore
the survey findings in relation to usage behaviours probably understate some or all of the true
population parameters.
• Relationship between Household Size and Usage
The survey results show the same positive correlation between household size and usage as
was found in 2003 albeit with a substantial downward shift in volumes. The variation in usage
around the mean for each household size is as large as it was in 2003 reaffirming that whilst
household size is a major determinant of usage it is not a good indicator of usage.
• Showers
The frequency of showering has not changed significantly since 2003 remaining around an
average of 0.9 showers per person per day.
Conversely there is a modest but statistically significant reduction in the average duration of
showering with an average of 5.7 minutes in 2007 compared to an average of 6.2 minutes in
2003.
Perhaps the biggest change in regard to showering is the incidence of 3 star (previously AAA)
showers which have increased their share of stock from 14% in 2003 to 23% in 2007. This
outcome reflects the success of showerhead exchange programs and 5 star homes regulations
that mandate 3 star showers in all new dwellings.
Typically householders run their shower at between one half and three quarters of the capacity
flow rate and overall average typical flow rate reduced from 10.6 litres per minute (Lpm) in
2003 to an average of 9.5 Lpm in 2007. The average typical flow rate for all showers with less
than 3 star rating was measured at 10.2 Lpm which is well below their average capacity but still
substantially higher than the average typical flow rate for 3 star showers which is only 6.8 Lpm.
• Toilets
The proportion of homes with at least one dual flush toilet has increased only marginally from
82% in 2003 to 83% in 2007. However the share of toilets that are dual flush increased from
77.5% of all toilets in 2003 to 81.2% in 2007.
Further classification of single and dual flush toilets into their various categories (6/3 litre, 9/4.5
litre etc) is problematic with some 15% of toilets unable to be accurately identified. Of those
that could be identified however 56% were found to be something other than 6/3 litre or 4.5/3
litre dual flush toilets indicating substantial potential remains for efficiency gains in this end use.
The average estimate of flush frequency was found to have decreased substantially to an
average of 2.7 flushes per capita per day compared to an average of 3.7 in 2003. The extent of
this decrease is surprising and may be questionable given the degree of difficulty of estimating
this parameter.
2
Average full and half flush volumes were generally found to be close to specification. The one
outstanding exception to this was for the half flush volume of 6/3 dual flush toilets where the
measured average flush volume was 3.7 litres or 23% above specification.
• Clotheswashers
The penetration of front loading washing machines increased from 21% in 2003 to 29.5% in
2007, an average increase of 2.1% per annum. This rate of increase mirrors that found
between the 1999 and 2003 surveys.
The average number of loads of washing per week was found to be 4.3, substantially lower
than the average of 5.0 loads found in 2003. This drop is plausible given the voluntary
response to drought although the three surveys have demonstrated this parameter to be
particularly volatile varying between 3.8 in 1999 and 5.0 in 2003.
There is a very strong correlation between the number of people in the household and the
number of loads washed per week enabling a simple model to be formulated to estimate
average loads for each household size. Using this model with Yarra Valley Water’s average
household size of 2.73 persons gives an average of 4.1 loads per week.
The use of automatic water level selection continues to increase and now is the commonly
selected water level in 37% of households up from 28% in 2003.
As was the case in 2003 very little clothes washing was found to be done by hand with 68% of
households doing no hand washing at all with the majority of the balance doing 90% or more of
their washing by machine.
• Dishwashers
Fifty eight percent of households were found to have a dishwasher down from 62% in 2003.
However this drop is not statistically significant and intuitively it is unlikely that the household
penetration of dishwashers would have declined. Of those households with a dishwasher 6%
indicated they never used it so in fact only 55% of all households actually use a dishwasher to
wash their dishes.
The average use of a dishwasher is 3.8 times per week, significantly lower than the average
4.4 times found in 2003. Most households still wash some of their dishes by hand but in
houses without automatic dishwashers hand washing is undertaken an average of 10 times per
week compared to only 5.6 times per week in houses with automatic dishwashers.
Eighty four percent of households do their hand washing of dishes with the plug in the sink
down from 92% in 2003.
• Indoor Tap Use
Indoor tap use occurs at hand basins in the bathroom or ensuite and at the kitchen and laundry
sinks.
The average typical or usual flow rate for hand basins was measured at 8 Lpm compared to
just 4.9 Lpm in 2003. However the high end range of flow rates suggests that in many cases it
3
was the “capacity” flow rate rather than the “typical” flow rate that was in fact measured.
Therefore the 2003 survey data are considered more reliable for this particular parameter.
There was a significant decrease in the frequency of use for the hand basin with average uses
per person decreasing from 5.5 times per day in 2003 to an average of just 3.5.
Over seventy percent of households have either an aerator, flow controller or both on their
kitchen sink tap. The use of aerators is far more common than flow controllers but these have
only a relatively small reducing effect on the capacity flow rate compared to flow control
devices. The average capacity flow rate of kitchen taps was found to have decreased from 19
Lpm in 2003 to 15 Lpm in 2007.
At just over 20.2 Lpm the laundry trough taps had the highest average measured flow rate of
the indoor taps although this has decreased significantly from the average 25.7 Lpm found in
2003.
Incidence of small leaks at taps was generally found to be low but nevertheless higher than
was found in 2003. Nearly 5% of laundry taps were found to have a small leak whilst 4.4% of
kitchen taps had a leak.
• Baths
Bath use by adults remains minimal with 78% of households having no adult use of the bath at
all. Average usage per adult is less than 0.2 baths per week. On average when the bath is
used by an adult it is just half filled.
Bath use by children is far more frequent although still not widespread with baths being taken in
just 21% of households. For households with children less than 12 years of age that use the
bath the average use is 2.5 baths per child per week.
Over ninety percent of households where children use the bath only fill to half the full capacity
of the bath or less.
• Evaporative Air Conditioners
The percentage of households with an air conditioner increased from 66% in 2003 to 73% in
2007. This increase has been almost solely in evaporative units which are now in 27% of
households.
On hot days the average estimated duration of use for evaporative coolers is 6.2 hours which is
around an hour longer than the estimated 5.3 hours in 2003.
• Gardens
Because the survey was undertaken during severe drought restrictions there is less potential to
investigate current behaviours than in previous surveys. It also limits comparison with the 2003
survey in some cases. For example in 2007 irrigation with a bucket or watering can is the most
common methodology used to irrigate garden beds but this has to be viewed in the context that
manual and automatic sprinkler systems are currently prohibited. However respondents were
asked how they anticipated they would irrigate their lawns and gardens when restrictions were
lifted and these provided some useful insights into how behaviours might differ in the future.
4
Ninety one percent of surveyed properties had some sort of garden. However under Stage 3a
restrictions 32% of homes with gardens (as distinct from lawns) do not water them at all. Even
when restrictions are lifted 26% of homes still said they would not be watering their garden.
In the case of lawns 65% of homes with gardens indicated they would not irrigate them when
restrictions are removed. These findings suggest a permanent behavioural change in outdoor
use may have occurred as a result of extended drought restrictions.
Perhaps influenced by restrictions garden watering events are of fairly short duration with most
garden irrigation being undertaken for only 15 minutes to half an hour.
When restrictions are lifted the dominant garden irrigation methodology would return to being
the hand held hose with relatively little use of both manual and automatic sprinkler systems.
However for lawn irrigation slightly more watering would be undertaken with sprinkler systems
than with the hose.
Householders generally considered that their garden had survived well during the drought but
were less positive about their lawns where 22% felt their lawn had died.
Use of rain sensors is rare with just 5% of households using one whilst soil moisture sensors
are extremely rare with only 1% of households using them. However the ownership of unused
rain and moisture sensors is considerably higher probably as a result of Stage 3a restrictions.
• Rainwater Tanks
The penetration of rainwater tanks has increased to 19% of households compared to 7.4% in
2003. One in five rainwater tanks are connected to toilet mostly in addition to the garden
although a small percentage of tanks are just connected to the toilet.
One third of homes built in the last 5 years have a rainwater tank and more than one third of
these are connected to toilet as well as garden.
• Greywater
Whilst ownership of permanent greywater systems is fairly rare (3%) reuse of greywater is
widespread with around 70% of homes using it to some extent. The predominant forms of
greywater reuse are from the shower and clotheswasher with 67% of households using either
or both of these sources.
• Swimming Pools
Although ownership of swimming pools at 8% was found to be slightly lower than in 2003 this is
not a statistically significant reduction. Forty five percent of homes with swimming pools now
use rainwater to top up their pools either solely (26%) or in conjunction with potable water
(19%).
5
1 Introduction
In 2003, Yarra Valley Water (YVW) undertook its first Appliance Stock and Usage Pattern
Survey. The objectives of the Survey were to assess the current levels of penetration of water
efficient and standard efficiency appliances and to collect behavioural data in regard to these
appliances. In order to do these types of surveys it is necessary to make household visits to a
large number of residential households.
The results of the survey were published as an online document on YVW’s website and
distributed freely to all interested parties. Together with the companion 2004 Residential End
Use Measurement Study, it provided valuable information for water conservation planning and
demand forecasting.
Since the 2003 survey there have been substantial changes in appliance efficiency and use
arising from the extreme drought, severe water restrictions and more intensive water
conservation campaigns. Understanding these changes is paramount in an environment
challenged by climate change and water scarcity. Accordingly in the period August to October
2007, YVW undertook a repeat of the Appliance Stock and Usage Pattern Survey, with
assessors visiting 850 households.
Changes to the 2003 survey were deliberately limited to relatively minor additions to facilitate
comparison of results with the 2007 survey. However in some cases comparison is not valid
because of differences in the drought restrictions in place at the time of the surveys.
2 Methodology and Sampling
2.1 Methodology
The appliance stock survey undertaken in 2007 follows the stock survey completed in 2003.
These are respectively called ASUP2007 and ASUP2003 in this report. The findings of
ASUP2007 will be compared with the findings of ASUP2003 and the Residential Forecasting
Study (May 2000) where possible.
The management of the household surveys was carried out by Coomes Consulting Group who
partnered with Victoria University’s Engineering faculty to undertake the surveys. Unlike in
ASUP2003 no pilot survey was done in ASUP2007 but a familiarisation round was undertaken
to gain valuable hands on experience for the assessors who were final year civil and
environment engineering students.
The intention of the familiarisation round of household visits, under the direct supervision of
Coomes and Yarra Valley Water staff, was to provide some guidance to assessors as well as
standardise as much as possible the techniques used to ask the questions and carry out the
flow measurements.
Stage 1 water restrictions were introduced on 1 September 2006 and this progressed rapidly to
Stage 2 on 1 November 2006, Stage 3 on 1 January 2007 and Stage 3a on 1 April 2007. The
survey started on the 11th of August and was completed in mid October and the entire survey
period was under stage 3a water restriction. Under Stage 3a, outdoor water use was severely
6
limited, with garden watering permitted only twice a week within limited time windows. There
were no restrictions on indoor water use but, as the extremity of the drought was extensively
publicised in the media and water conservation messages intensified, there is a likely impact on
indoor water use behaviour and appliance selection.
The survey covered 850 households of which 119 were rental properties. Field visits were done
only during the weekends and 26 assessors worked from 8 am to 5 pm on both days.
Completed questionnaires were electronically forwarded to YVW weekly by the consultants and
any anomalies were reported back to the consultants before the commencement of the next
round enabling the assessors to continually improve quality of data and measurements. Pre
loaded customer data and a highly improved version of the computer software used in
ASUP2003 made data collection easier and faster compared to the previous survey.
As was the case for ASUP2003 the household visits enabled a number of measurements to be
made. These included the typical and capacity3 flow rates of all showers, the typical flow rate
for bathroom basins and the capacity flow rates of kitchen and laundry taps. Toilet flush
volumes were also measured although assessors were advised to skip this step in cases where
they considered the appliance or surrounding area might be damaged or was not accessible.
2.2 Sampling frame.
Yarra Valley Water contains some 114 postal areas covering around 4,500 sq kilometres
including the township of Wallan to Melbourne’s north4. Given the large coverage area it was
decided to use a stratified sample with respect to geographic location. Limiting the number of
postal areas to 17 in the sample made the task of scheduling of appointments and meeting
time commitments substantially easier.
Postal areas were grouped into five consumption categories based on 2005/06 financial year
annual water consumption. Four clusters of suburbs were selected to represent all the five
groups (see Figure 2-1 below). The township of Wallan was included because no data had
been collected for this area previously and being separate from the greater Melbourne area it
could potentially have a distinctive appliance profile.
An initial sample of 15,000 customers was randomly selected from Yarra Valley Water’s billing
system in proportion to the actual number of customers in each of the selected suburbs. This
formed the sampling frame from which a final sample of 850 households was chosen.
The “typical” flow rate is the flow rate of the appliance indicated by the household member accompanying the
assessor as being representative of the flow rate used in the household. Clearly there can be no guarantee that
the flow rate indicated is representative (or typical) of all household members. The “capacity” flow rate is the
measured rate when the cold tap is fully turned on.
4 Prior to 2006 the township of Wallan was part of Goulburn Valley Water’s supply area. It is located approximately
50 km to the north of Melbourne.
3
7
Figure 2-1: Sample Location & Usage Level
2.3 Recruitment of Survey Participants.
The task of recruiting 850 of the customers from 15,000 was outsourced to a third party (Ipsos).
Initially a letter was sent to all the customers asking them to express their interest in
participating. Appendix A contains the initial contact letter sent out to the customers.
Customers could self-register using either a specially established 1800 number or a link on
Yarra Valley Water’s web site. Subsequently these customers were contacted over the phone
to confirm their participation. Alternatively customers could wait to be contacted should selfregistration not result in sufficient sample size. Customers were offered a $40 MYER gift
voucher as an incentive to participate.
In recruiting for the sample Ipsos were provided with the population characteristics for each
suburb including
• Ratio of owner occupied to tenant properties
• Ratio of houses to flats/units/apartments
• Ratio of pensioners and concession card holders to standard customers.
8
If self registration did not deliver the required population characteristics then Ipsos would phone
the remaining letter recipients until the required quotas were filled. Table 2-1 below shows the
makeup of the 850 households in the sample.
Table 2-1: Customer matrix for the sample of 850 households.
Number of Customers
Standard
PostCode
3056
3058
3060
3074
3085
3088
3095
3106
3125
3128
3137
3144
3149
3150
3756
3765
3787
Total
Owner
Flats
Houses
10
22
6
35
1
10
1
18
4
18
6
42
4
53
3
26
4
16
10
17
2
18
8
14
10
44
8
80
0
11
0
10
0
2
78
436
Pensioner/Concession
Tenant
Flats
Houses
7
10
4
8
1
2
1
3
1
3
3
4
2
2
1
2
1
3
6
3
1
2
1
1
3
6
3
10
0
1
0
1
0
0
34
62
Owner
Flats
Houses
1
10
2
25
0
15
0
22
1
6
2
13
1
7
2
6
1
6
3
6
2
6
1
2
4
20
5
29
0
2
0
3
0
0
25
182
Tenant
Flats
Houses
2
2
2
5
0
2
1
5
0
1
1
1
0
0
0
0
0
2
2
1
0
2
0
0
1
2
1
5
0
0
0
0
0
0
8
25
2.4 Representativeness of Sample
To understand how well the sample reflects the whole Yarra Valley Water population of
residential customers the sample was assessed on the basis of the quarterly billed water usage
of participants. The usage period analysed was the average litres per property per day
(L/prop/day) over the four quarters ending September 2007.
The average daily usage per property for the sample over this 12 month period was 459 litres.
This average is 6.3% below the average daily usage of 490 litres for the total Yarra Valley
Water population of residential properties. To put this difference in context we need to consider
the distribution of residential usage which typically demonstrates very high variance.
Consequently, despite a reasonably large sample size, it would require a certain amount of
good luck for the population and sample averages to be aligned more closely.
Yarra Valley Water’s residential usage always demonstrates a lognormal distribution with
significant skew to the right (ie large users). Typically the median usage level is 10% lower than
the average or mean usage level. The distributions of both the sample and the population are
shown in Figure 2-2 below and it is evident that the sample has representation across the full
range of usage but is slightly over-represented below average usage compared to the
population.
9
Figure 2-2: Distribution of Annual Usage
Distribution of Residential Average Litres per Day - Annual to Sep 07
9%
Sample Average 459 LpD
Population Average 490 LpD
8%
7%
% of Customers
6%
5%
YVW Population
ASUPS Sample
4%
3%
2%
1%
040
40
-80
80
-1
12 20
01
16 60
02
20 00
0-2
24 40
02
28 80
0-3
32 20
03
36 60
04
40 00
0-4
44 40
04
48 80
0-5
52 20
05
56 60
060
60 0
0-6
64 40
06
68 80
0-7
72 20
07
76 60
080
80 0
0-8
84 40
08
88 80
09
92 20
096 960
010 1000
00
10 104
40 0
10 108
80 0
11 112
20 0
11 116
60 0
-1
12 20
00 0
12 124
40 0
-12
8
>= 0
12
80
0%
Usage Band (litres)
Two possible obvious factors for the lower average sample usage can be ruled out. Firstly the
average household size for the sample is 3.0 persons which is higher than the Yarra Valley
Water overall average of 2.73 (ex 2006 Census). Secondly the proportion of lower consuming
“Other”5 dwellings in the sample is only 16% compared to the population proportion of 21%.
We can do little more than conclude that the lower than average sample usage is the outcome
of either a slightly more efficient appliance profile or more efficient usage patterns than the
population or some combination of both. This finding needs to be kept in mind in interpreting
the results of the survey.
5
“Other” dwellings are defined as all non separate houses such as flats, units and apartments
10
3
Usage and Household Size
The clear positive correlation between household size and household water usage is well
known. However, it is important to recognize the large variation around the average for a given
household size. For example consumption of a given household size will often exceed the
consumption of a much larger household because of differing behaviours. Hence, it is possible
for even large samples to give biased results if the full range of behaviours is not represented.
3.1 Average Daily Usage by Household Size
The annual usage statistics for each household size are shown in Table 3-1. The wide variation
in residential usage discussed in section 2.4 is further evidenced by the very large standard
deviations of usage relative to the means for each household size.
The table also shows per capita consumption within each household size. As the household
size decreases there is a marked increase in per capita usage indicating significant economies
of scale with regard to household size.
Table 3-1: Usage Statistics for each Household Size6.
Average
Median
Usage per Usage per Average
Household Number of
Annum
Annum
Usage
Size
Households
KL
KL
LpD
Median
Usage
LpD
Standard
Deviation
LpD
Average
Per Person
LpD
1
124
86
72
231
192
170
231
2
272
141
128
382
343
190
191
3
142
173
157
473
427
212
158
4
186
204
179
556
494
237
139
5
83
252
230
685
604
351
6+
42
257
236
700
640
396
137
101
Total
849
169
149
459
409
273
170
Figure 3-1 below shows the median annual usage for each household by household size and
its range7. The chart demonstrates the broad relationship between household size and annual
consumption.
Also from the chart it is evident how the range of annual consumption overlaps across different
household sizes. It is worth noting that the 2007 average usage per person per annum across
all household sizes is 28% less when compared to 2003.
6 Usage is for the twelve months ending September 2007. Only the households with four consecutive bills
considered for the above analysis.
7 The line within the box is the median and the box represents the interquartile range, the values from the first to
third quartile. The single bars above and below the box represents 1.5 box lengths above and below the
interquartile range. The circles represent outliers which are between 1.5 and 3 box lengths from the upper or lower
edge of the box. The extreme points * are more than 3 box lengths.
11
Figure 3-1: Range of Annual Usage for each Household Size8
Annual Average Litres per Day
1,600.0
1,400.0
1,200.0
1,000.0
800.0
600.0
400.0
200.0
0.0
1
2
3
4
5
6
7
8
No. People in Household
3.2 Summer versus Winter Usage by Household Size
The relationship between household size and water usage is better seen if we consider winter
(indoor) and summer (indoor & outdoor) usage separately.
Winter usage is represented by the September quarter billing data and the expectation is that
the virtual exclusion of garden watering from the data (assumed to be independent of
household size) should result in a stronger relationship between household size and usage.
This is evident in Figure 3-2 below where there is a stronger linearity and the range of usage
within each household size demonstrates less overlap than shown in the summer quarter (see
Figure 3-3).
Note that the anomalous trends for households with 6 and 8 persons evident in Figure 3-1 to
Figure 3-3 are assumed to be due to the very small number of large households in the sample.
8 Usage for the 12 months ending September 2007 under various stages of restrictions. Stage 1 restrictions from
September 2006, Stage 2 from November 2006, Stage 3 from January 2007, Stage 3a from April 2007.
12
Figure 3-2: Range of Winter (September 2007 qtr) Usage for each Household Size
Avg Litres per Day Sep Qtr 2007
1,600.0
1,400.0
1,200.0
1,000.0
800.0
600.0
400.0
200.0
0.0
1
2
3
4
5
6
7
8
No. People in Household
Figure 3-3: Range of Summer (March 2007 qtr) Usage for each Household Size
Avg Litres per Day March Qtr 2007
2,500.0
2,000.0
1,500.0
1,000.0
500.0
0.0
1
2
3
4
5
6
No. People in Household
13
7
8
3.3 Modelling Usage with Household Size.
3.3.1 Annual Modelled Water Usage per Household
The relationship between household size and usage can be modelled using a simple power
function of the form:
Litres per Dayi = K * HHsizeib , for household size of i.
where K is a constant and b is a power representing the household size elasticity. The
modelled usage for the 2007 sample data is shown in Figure 3-4 below with the model
equation:
Litres per Dayi = 245 * HHsizei0.6
The household size elasticity of 0.6 can be interpreted as a 0.6% change in household usage
for each 1% change in household size. For example a 1% decrease in household size will
result in usage decreasing by 0.6%.
Applying the above model to the overall Yarra Valley Water average household size of 2.73
indicates an average daily per capita use of 164 litres for the 12 months to the September
quarter 2007.
Figure 3-4: Household Usage & Household Size
Annual Usage & Household Size - All Dwellings
1200.0
1000.0
Modelled Use (Litres) = 245*(HH Size).60
Litres per Day
800.0
600.0
2007 ASUPS
Modelled Use
2003 ASUPS
400.0
200.0
0.0
1
2
3
4
5
6
7
No. Persons in House
The 2007 modelled usage is significantly lower than the modelled usage in 2003 (LpD = 336 *
HHsize0.59) which is also shown in Figure 3-4. The powers in both models are very similar but
the base usage is reflecting a 26% downward shift. A small part of this decrease can be
attributed to the 2007 sample having average usage 6% lower than the population average.
However the majority of the decrease can be attributed to both the direct impact of Stage 3a
14
restrictions on outdoor use and the voluntary reduction in indoor usage through the adoption of
efficient appliances and more efficient usage patterns.
3.3.2 Modelling per Capita Usage with Household Size
The household usage model can be divided through by household size to give a “Per Capita”
model as follows:
Daily per Capita Use (Litres) = 245 * HHsize-0.4
This enables us to estimate a very important relationship that impacts on future water
resources planning namely that as the average household size declines, in the absence of
other changes, per capita usage will increase. This effect is shown in Figure 3-5 below and the
power in the model indicates that for each 1% decrease in household size, average per capita
use will increase by 0.4%.
Figure 3-5: Per Capita Usage and Household Size
Average Per Capita Use by Household Size - All Dwellings
300
250
Modelled Per Capita Use (Litres) = 245*(HH Size)-0.4
Litres per Day
200
150
100
50
0
1
2
3
4
5
6
7
No. Persons in House
The long term trend decline in average household size that has been occurring in Melbourne
for over two decades therefore has an upward influence on per capita usage.
15
4 Survey Findings – Indoor Use
4.1 Showers
4.1.1 Frequency of Showering
Residents were asked to estimate the number of times each shower is used during a week by
all members of the household. Like many of the questions in the survey the respondent is
asked to make an estimate on behalf of the household.
The average number of showers per person per week is estimated to be 6.0 for 2007 while it
was 6.2 in 2003. The 95% confidence interval for this parameter is [5.8, 6.3]. The apparent
reduction in frequency from 2003 to 2007 is not statistically significant (two tailed test, 90%
level).
By far the most common frequency of showering is once per day (37%) whilst 75% of people
shower between 4 and 7 times per week. Comparison of the two surveys shows that the
distribution for frequency of showering has not changed much since 2003 (see Figure 4-1).
Figure 4-1: Frequency of Showering
Frequency of Showering
45%
40%
ASUP 2007
ASUP 2003
35%
Average Freq: 6.0 per week
Std.Deviation: 3.1
Median Freq : 6.5
Relative Frequency
30%
25%
20%
15%
10%
5%
0%
1
2
3
4
5
6
7
8
9
10
11
More
Showers per Capita per Week
4.1.2 Shower Duration
Respondents were asked to estimate the average duration of their showers. The most common
shower duration is 5 minutes in both surveys, this being preferred by almost a third of
respondents. The trend towards shorter showers is evident from Figure 4-2. In particular, there
has been a substantial increase in the proportion of respondents reporting average shower
durations of 3 and 4 minutes, in line with water conservation messages. In both surveys, there
16
appears to be a propensity for respondents to round out shower times to 5 and 10 minutes and,
to a lesser extent, 15 minutes.
ASUP2007 estimates that current average shower duration is 5.7 minutes with a median of 5
minutes compared with 6.2 mins and 5 mins respectively in 2003. This is a statistically
significant reduction in duration at the 99% level9. The 95% confidence interval for this
parameter is [5.5, 5.9].
In ASUP 2007, 85% of respondents’ average shower duration is in the range 3 to 8 minutes.
Ninety six percent of respondents showered for 10 minutes or less.
Figure 4-2: Distribution of average shower duration.
Shower Duration (in miutes)
40%
35%
ASUP 2007
Average Duration : 5.7 minutes
Std Deviation : 3.2
Median Duration : 5 minutes
Relative Frequency
30%
25%
20%
15%
ASUP 2007
ASUP 2003
10%
5%
0%
1
3
5
7
9
Duraton (minutes)
11
13
15
Longer
Whilst 15% of households have one, only 10% of the households are actually using a shower
timer (see Table 4-1 below). Noticeably 35% households expressed that they would like to
have a shower timer and still looking for one.
Half of the households said that they do not want a shower timer. It is not clear whether this is
due to the fact that they are already having efficient showers or they don’t feel the need to
reduce their shower duration.
Whilst it is possible to test for significant differences between the 2003 and 2007 surveys on a statistical basis it
needs to be remembered that the relative ability of respondents to estimate various parameters on behalf of the
household cannot be accounted for.
9
17
Table 4-1: Shower Timer Facts.
Shower Timer
Percent of
Households
Have a shower timer and
using it
10%
Have a shower timer and
don't use it
5%
Don’t' have a shower timer
but would like to
35%
Don't want a shower timer
50%
4.1.3 Shower Capacity Flow Rate
As in the previous survey both capacity and typical flow rates were measured for all the
showers in the household. Capacity flow rate was measured by opening both hot and cold
water taps to full capacity. Typical flow rate was measured by asking the respondent to turn the
shower on to the typical flow rate that was normally used when showering.
Measurement of the capacity flow rate allows showerheads to be categorised under the WELS
star rating scheme as shown in Table 4-2.
Table 4-2: Shower capacity flow rate.
Proportion
Proportion
Shower Capacity
Equivalent
of
of
Flow Rate
Efficiency
Showers
Showers
Rating
ASUP 2007
ASUP 2003
up to 9 lpm
***
23%
14%
9.1 - 12 lpm
**
21%
9%
12.1 - 15 lpm
*
15%
9%
15.1 - 18 lpm
Std
14%
7%
18.1 - 21 lpm
Std
8%
10%
over 21 lpm
Std
20%
51%
In ASUP2007, 23% of showers were identified as 3-Star, delivering a maximum of 9 litres per
minute (Lpm). This is a significant increase over the 14% recorded in ASUP2003 and is
indicative of the impact of both the Yarra Valley Water showerhead exchange program10 which
has seen 73,000 showerheads exchanged over the last 2 financial years and 5 star homes
regulations which require a 3 star shower in all new homes.
In 2007, only 20% of showerheads surveyed had a capacity rate of more than 21 Lpm
compared to 51% in 2003. In addition to the factors mentioned above this latter result may also
The showerhead exchange program enables customers to swap their standard showerhead for a 3 star shower
at no cost.
10
18
be influenced by the extensive pressure reduction program implemented by Yarra Valley Water
over the past several years.
Overall average capacity flow rate is estimated to be 15.3 Lpm in 2007 compared to 19 Lpm in
2003.
Further analysis done on the distribution of shower heads by age of the property, (less than 5
years, between 5 to 10 and more than 10 years), shows the proportion of 3-Star showerheads
is consistent at around 23% across all age categories.
4.1.4 Shower Typical Flow Rate.
The distribution of typical shower flow rate is given in Figure 4-3 for both surveys. There is
evidence of a reduction in the proportion of showers with typical flow rates above 13 Lpm and a
significant increase in the proportion of showers operating in the range 7 to 9 Lpm. In 2007,
over 54% of respondents operate their showers between 5 and 9 Lpm.
Figure 4-3: Distribution of Shower Typical Flow rate
Distribution of Shower Typical Flow Rate
30%
Relative Frequency
25%
Average Flow Rate : 9.5 lpm
Std Deviation : 5.5
Median Flow Rate : 9 lpm
20%
15%
10%
ASUP 2007
ASUP 2003
5%
>2
3
21
-2
3
1
19
-2
9
-1
17
17
15
13
to
to
15
13
to
11
9
to
11
9
7
to
7
5
to
5
to
3
<=
3
0%
Litres per minute
The overall average typical shower flow rate in ASUP 2007 is 9.5 Lpm compared with 10.6 Lpm
for ASUP 2003. This is a statistically significant reduction at the 99% level. This reduction in
average flow rate is mostly due to the lower proportion of non efficient showers rather than an
across the board reduction in flow rate for particular shower types. In fact the average flow rate
for the 3 star showers has increased from 6.1 Lpm in 2003 to 6.8 Lpm in 2007. A comparison of
typical flow rates for each capacity category of showers is shown in Table 4-3.
19
Table 4-3: Typical Flow Rate (Lpm) by Shower Type
Average
Average
Typical Flow Typical Flow
Shower Capacity
Rate 2007
Rate 2003
up to 9 lpm
6.8
6.1
9.1 - 12 lpm
8.2
7.6
12.1 - 15 lpm
9.4
9.0
15.1 - 18 lpm
10.3
10.2
18.1 - 21 lpm
11.4
11.6
over 21 lpm
12.7
12.5
4.1.5 Ratio of Typical to Capacity Flow Rate
Understanding of the level of ‘throttling’ back from the capacity flow rate to typical flow rate in
showers is particularly important in estimating possible water savings resulting from efficient
shower retrofit programs. Figure 4-4 shows the relationship between the typical and capacity
flow rate (ie the throttle ratio) of showers for the two surveys.
It shows a fairly consistent reduction in the throttle ratio as the capacity of the showerhead
increases. Whereas 3 star showerheads are typically operated at about three quarters of their
capacity, the least efficient models are operated at only about half their capacity.
Figure 4-4 also shows a higher throttle ratio in 2007 for the lower capacity showers compared
to the 2003 survey. For example the average typical flow rate of 3 star showers is 6.8 Lpm
versus 6.1 Lpm in 2003.
Figure 4-4: Ratio of typical to capacity flow rates.
Ratio of Typical to Capacity Shower Flow Rates (n=1199 showers)
14.0
0.80
0.70
12.0
0.60
0.50
8.0
0.40
6.0
0.30
4.0
0.20
Avg Typical Flow Rate ASUP 2007
Avg Typical Flow Rate ASUP 2003
2.0
Throttle Ration ASUP 2007
0.10
Throttle Ration ASUP 2003
0.0
0.00
<=9 l/m
9.1 - 12 l/m
12.1 - 15 l/m
15.1 - 18 l/m
Capacity Flow Rate (l/m)
20
18.1 - 21 l/m
>21 l/m
Throttle Ratio
Typical Flow Rate (l/m)
10.0
4.1.6 Time Delay for Hot Water
For each shower assessor measured the time delay before hot water was delivered. For 54%
of showers the delay was 10 seconds or less (see Figure 4-5). Eighty three percent of showers
had a delay of 20 seconds or less.
Figure 4-5: Hot Water Time Delay for Shower
Hot Water Delay
60%
54%
50%
% of Showers
40%
30%
19%
20%
10%
10%
5%
6%
6%
26 to 30
> 30
0%
1 to 10
11 to 15
16 to 20
21 to 25
Seconds
It should be noted that this measure can be considered as indicative only as there is no way of
controlling how long the shower was used prior to the measurement being taken.
21
4.2 Toilets
Over the last two decades the flush volume of toilets in common use in Melbourne has
changed significantly as a result of regulations that have mandated the type of toilet that must
be installed both in new homes and when existing homes are renovated.
The first dual flush toilet (11/6) was introduced and made mandatory in 1982. In 1989 the 9/4.5
litre dual flush toilet was launched and made mandatory shortly after. The 6.3 litre dual flush
toilet replaced the 9/4.5 litre version in 1993. Currently 4.5/3 litre dual flush toilet is the
predominant toilet type in the market although at this stage it is not mandated.
The average number of toilets per household is estimated at 1.7 in ASUP2007 compared to 1.6
in ASUP2003. The number of households with at least one dual flush toilet was found to have
increased only marginally from 82% in 2003 to 83% in 2007.
4.2.1 Type of Toilets
Whilst it is very simple to identify dual flush and single flush toilets classification of toilets into
specific types is a problematic exercise firstly because the type is often not clearly identified on
the toilet and even measured flush volumes can be misleading due to the use of flush
controllers and displacement devices.
Data on usage and flush volumes of toilets were collected in the nine categories as shown in
Table 4-4. Assessors identified the type of toilet either by observation or by asking the
householder or a combination of both. In some cases where the measured flush volumes were
clearly at odds with the initial classification that classification may have subsequently been
amended. However it is not apparent to what extent this occurred. This approach differs from
that used in the 2003 survey where the type was essentially based on the measured flush
volumes.
Another factor influencing the quality of the 2007 data may be the use of some 26 assessors in
2007 each with limited experience versus just 2 assessors in 2003 with considerable
experience. Consequently, other than the single/dual flush distinction, the reliability of 2007
survey toilet type data is considered to be lower than the 2003 data.
In 2007, 81.3% of toilets were dual flush, compared to 77.5% in 2003 (see Table 4-4 ). This
3.8% increase in the ownership of dual flush toilets over the four year period is to be expected
since it has been mandatory to install 6/3 or better toilets since 1993.
The other notable feature is the 6.7% share of 4.5/3 dual flush toilets since their introduction in
October 2004, indicating a rapid gain in market share for this toilet type. Comparing the 6/3
dual flush share from 2003 (39.6%) with the combined 6/3 and 4.5/3 dual flush share from 2007
survey (37%) indicates a decrease in share that is considered unlikely to be real.
Similarly the survey results showing increases in the ownership of the “11 Single” and “11/6
Dual” toilets are not considered to be realistic and may reflect the uncertainties referred to
above. The substantial decrease shown in the ownership of the “9 Single” toilets (from 12.7%
to 4.5%) possibly reflects the different methodology employed in 2003 where toilet
categorisation was mostly influenced by the measured flush volume.
22
Note that for over 15% of toilets it was not possible to identify the specific type, only whether it
was single or dual flush.
Table 4-4: Toilet Ownership by Type of Toilet.
Toilet Type
11 Single
11/6 Dual
9 Single
9/4.5 Dual
6 Single
6/3 Dual
4.5/3 Dual
Not Sure Single
Not Sure Dual
All Dual Flush
Toilet
Ownership
ASUP2007
Toilet
Ownership
ASUP2003
8.5%
10.3%
4.5%
22.2%
1.9%
30.3%
6.7%
3.7%
11.8%
81.3%
7.3%
4.7%
12.7%
33.2%
1.7%
39.6%
77.5%
4.2.2 Toilet Leaks.
ASUP2007 found 3.2% of toilets to have a leak (See Table 4-5). Further it was found that 5.2%
of households had at least one leaky toilet. The comparable figures in ASUP2003 are 2.3% and
3.7% respectively.
Leaking toilets are more commonly older toilets such as 11 and 9 litre single flush toilets. In
ASUP2003, only 4% of the “11 Single” toilets were found to leak, however this proportion has
more than doubled over the past four years. The majority of leaks were assessed as minor with
major leaks being reported only in 11 litre single flush toilets.
Table 4-5: Percentage of Toilets that Leak
by Toilet %
Type
% Leak
Leak
ASUP2007
ASUP2003
Toilet Type
11 Single
8.7%
4.0%
11/6 Dual
4.2%
4.6%
9 Single
4.7%
4.1%
9/4.5 Dual
2.8%
2.0%
6 Single
0.0%
0.0%
6/3 Dual
0.9%
1.5%
4.5/3 Dual
2.1%
NA
Not Sure Single
7.8%
NA
Not Sure Dual
4.2%
NA
All
3.2%
2.3%
23
4.2.3 Toilet Flush Volume
It is often not possible to make an assessment of toilet flush volumes simply by observing the
toilet type. This is because different toilets can have an identical looking cistern (eg 9/4.5 and
6/3) and also because of the addition of flush controllers and displacement devices such as
bricks and water bottles in the cistern to reduce the flush volumes. Consequently it is
necessary to physically measure the toilet full and half flush volumes.
A simple method such as closing the stop tap, marking the water level inside the cistern before
flushing and refilling it to the same level with a calibrated jug was used to measure full and half
flush volumes. This methodology differs from that employed in the 2003 survey where a device
called the T-5 Flushmeter was utilised to measure flush volumes (refer to section 3.2.3 of
ASUP 2003 report).
For cisterns that were located behind walls or were difficult to open, the assessors were asked
not to attempt measuring the flush volumes. Flush volumes were recorded against 90% of the
total number of toilets however it is not certain whether all the data collected was in fact
“measured”. This uncertainty is based on the view that incidences of identical full and half flush
volumes for two and sometimes three toilets in the household are unlikely to occur at the
frequency found in the survey. Nevertheless all collected data is included in the reported flush
volumes below.
Table 4-6 shows the average measured full and half flush volumes by toilet type. On average
the full flush volume was found to be close to the specified volume however the half flush
volumes were found to be above specification on average.
Table 4-6: Measured flush volume by Toilet type.
Avg Full
% variation
Avg Half
Type of Toilet
Flush
from
Flush
& Flush Volume (litres)
Volumes specification Volumes
% variation
from
specification
11/6 litre dual flush
10.8
-1.5%
6.2
4.0%
9/4.5 litre dual flush
8.5
-5.3%
4.6
3.3%
6/3 litre dual flush
6.2
3.6%
3.7
23.3%
4.5/3 litre dual flush
4.6
2.6%
2.9
-2.9%
11 litre single flush
10.7
-2.5%
na
na
9 litre single flush
8.6
-5.0%
na
na
6 litre single flush
5.9
-1.1%
na
na
All Toilets
-0.6%
11.5%
This latter result is largely driven by the 23.3% deviation from the specification for half flush of a
“6/3 Dual”, the only large deviation in the table. This is quite a different result to 2003 where this
deviation was only -3%. It is not clear what conclusions can be made from this outcome since it
could possibly reflect the large number of assessors in 2007 (resulting in greater variation) or
the different methodology used to measure volumes.
24
The variability around the measured average full flush volumes is shown in Figure 4-6 below.
The large single flush toilets show much greater variation than the smaller toilets perhaps
reflecting a higher incidence of intervention such as adding flush controllers or displacement
devices.
Figure 4-6: Variability of Flush Volume by Type of Toilet
Note that the interquartile ranges shown for 6/3 and 4.5/3 dual flush toilets in Figure 4-6 are
very narrow with relatively few toilets having either unusually small or high full flush volumes.
4.2.4 Frequency of Toilet Use
Respondents were asked to estimate how many times each toilet in the household was used
per week. These responses were combined with the household size data to determine the uses
per capita per day (pCpD) for each household. It is important to note the distinction between
“uses” pCpD and “flushes” pCpD given that there is a small level of double flushing that occurs
with each use11.
Figure 4-7 shows majority of people (74%) flush the toilet between 1 and 4 times per day with
an average of 2.7 uses per day. This is significantly lower than the average flush frequency
found in the 2003 survey of 3.7 flushes. Although there is anecdotal evidence that people are
It is unlikely that respondents are able to take this subtlety into account when estimating the frequency of use of
each toilet in the household. Consequently “uses” per day as estimated by respondents and “flushes” are taken to
be the same for simplicity of reporting. For modelling purposes therefore this parameter could be adjusted
upwards to account for an assumed level of double flushing.
11
25
flushing less (“if it’s yellow, let it mellow”) under the current more severe drought restrictions the
magnitude of this decrease in flush frequency is surprising.
One possible explanation is that some respondents could have answered this question
(“number of times each toilet is flushed per week”) on behalf of just themselves rather than on
behalf of the household as was intended. However a comparison of the flush frequencies from
both surveys just for single person households (thereby counteracting the above potential
error) shows the same level of decrease. It should be noted that this parameter is difficult to
estimate because for most households flush frequency is known to vary substantially from
weekdays to weekends12 and if this is not sufficiently allowed for this could result in the
parameter being understated.
Whilst the survey results strongly suggest a significant reduction in average flush frequency
since 2003, given that the mean water usage of the 2007 ASUP sample is lower than average
it is safer to conclude that the true population parameter lies somewhere between the 2003 and
the 2007 sample means. That is average flushes per person per day lies in the range [2.7, 3.7].
It also needs to be remembered that if in fact the reduction is real and is in response to the
current drought then there is potential for this parameter to jump back towards the 2003 level
when drought restrictions are eased or removed altogether.
Figure 4-7: Distribution of Flushes per Capita per Day
Distribution of Toilet Use per Capita per Day
35%
Average Freq : 2.7 Uses per Person per Day
Std Deviation : 1.6
Median: 2.5 Uses per Person per Day
30%
Relative Frequency
25%
20%
15%
10%
5%
0%
1 or less
1.1 to 2
2.1 to 3
3.1 to 4
4.1 to 5
5.1 to 6
6.1 to 7
7.1 or more
Number of Times used per Person per Day
4.2.5 Incidence of Double Flushing
In total around 43% of toilets are flushed more than once on occasion although for 23% of
toilets the incidence of double flushing was only “rarely” (Table 4-7). 15% of toilets are double
flushed about half the time whilst 5% are always double flushed.
A recent study undertaken by the CRC for Water Quality and Treatment (“Study of Water Usage in Urban
Areas” Research Report No. 53 Feb 2008, J. O’Toole, K. Leder, M. Sinclair) asked this question separately for the
weekdays and the weekends. The findings in that study were found to align more closely with the 2003 YVW
study.
12
26
Table 4-7: Incidence of Double Flushing
Type of Toilet
Never
Rarely
Half the time
All the time
11 Single
66%
11%
5%
18%
11/6 Dual
54%
19%
23%
3%
9 Single
64%
19%
7%
10%
9/4.5 Dual
47%
31%
18%
4%
6 Single
58%
17%
4%
21%
6/3 Dual
53%
26%
18%
3%
4.5/3 Dual
48%
40%
13%
0%
Not Sure Single
91%
4%
0%
4%
Not Sure Dual
77%
14%
7%
2%
All Type of Toilets
57%
23%
15%
5%
4.2.6 Toilet Flush Volume Reduction
Nearly 32% of toilets have some form of flush volume reduction (Table 4-8). The most common
flush volume control method is bending the float arm (19.2%). Flush controllers or cistern
weights were found to be installed in 8% of toilets whilst a relatively small 4.4% of toilets had a
displacement device although this is considerably higher for 11 litre single flush toilets at 10%.
Table 4-8 shows that even with dual flush toilets households are adopting various flush control
methods. It is interesting to note that even with highly efficient toilets households are trying
different toilet flush control methods.
Table 4-8: Adoption of Toilet Flush Control Methods
Flush Controller /
cistern weight
Displacement
Device
Bending floating
arm
66%
7%
10%
17%
64%
13%
2%
22%
84%
3%
7%
7%
60%
5%
8%
27%
63%
4%
13%
21%
71%
9%
3%
17%
83%
9%
3%
5%
78%
8%
0%
14%
68%
9%
1%
22%
68.3%
8.0%
4.4%
19.2%
Type of Toilet
11 Single
11/6 Dual
9 Single
9/4.5 Dual
6 Single
6/3 Dual
4.5/3 Dual
Not Sure Single
Not Sure Dual
None
All Type of Toilets
4.3 Clothes Washers
4.3.1 Ownership and Type of Washing Machine
Current residential clothes washer ownership is estimated to be 99.3% compared to 99% in
2003 (see Table 4-9). Washing machine penetration is slightly higher for owner occupied
27
homes (99.6%) than rented homes (99.2%). When compared with 2003 data, there is no
change in washing machine penetration in owner occupied homes while there is a marginal
increase for rented properties.
Table 4-9: Washing machine ownership by type.
Washing Machine Type
ASUP2007
ASUP2003
Top Loading
69.8%
78.0%
Front Loading
29.5%
21.0%
Have Washing Machine
99.3%
99.0%
The proportion of front loading washing machines has increased to nearly 30% over the last
four years from 21% in 2003. No significant difference was found between owner occupied and
rented homes in the ownership of the different types of the washing machines.
Assessors were also asked to collect the energy and water star rating of the clotheswasher but
as Table 4-10 shows it was possible to identify the water star rating for only 29% of
clotheswashers which is not surprising given the recent introduction of mandatory labelling. Of
those clotheswashers where the water star rating was identified 80% were rated as 3 star or
better.
Table 4-10: Water and Energy Star Rating - Clotheswashers
Percent of Clotheswashers
Star Ratings
Water
Energy
Up to 2.5 stars
6%
12%
3 to 3.5 stars
10%
19%
4 stars
9%
14%
4.5 stars
4%
7%
Unlabelled
68%
46%
Invalid/Missing
3%
2%
All Clotheswashers
100%
100%
4.3.2 Frequency of Clothes Washer Use
In 2007 the average number of washing loads per week per household is estimated at 4.3 with
a median of 4.0 and standard deviation of 3.1. The 95% confidence interval for this parameter
is [4.1, 4.5].
Around two thirds of households use the washing machine between 1 and 4 times per week
with 3 to 4 times being the being the most common frequency (see Figure 4-8). The chart
shows the comparison with the 2003 survey and the notable feature is the jump in the
percentage of two or less loads per week category from around 21% to 31%. This is at the
expense of the 5-6 loads per week frequency.
28
Figure 4-8: Distribution of Clotheswasher Use per Week.
Distribution of Clothes Washer Loads per Week
40%
35%
Average Freq: 4.3 (5.0 in 2003)
Std Deviation: 3.0 (3.3 in 2003)
Median Freq 4.0 (4.0 in 2003)
Relative Frequency
30%
25%
20%
ASUPS 2007
ASUPS 2003
15%
10%
5%
0%
1-2
3-4
5-6
7-8
9-10
11-12
12+
Loads per Week
A comparison of the overall average frequency of clotheswasher use across surveys is shown
in Table 4-11 below. The results from the 1999 survey have been included to demonstrate the
apparent volatility of this particular parameter. In 2003, the average number of loads per week
was 5.0 with median 4.0 and standard deviation 3.3. This decrease seen in 2007 is statistically
significant at greater than the 99% level. One could hypothesise that the decrease in the
average number of loads demonstrated in 2007 could be an impact of the drought. However
the average usage in 1999 was only 3.8 and at that time there were no drought restrictions in
place so it would appear that there are other contributing factors to the movements in the
estimates of this parameter.
Table 4-11: Clotheswasher – Frequency of Use
Clotheswasher 2007
2003
1999
Loads per Week
Average
4.3
5.0
3.8
Std Deviation
3.1
3.3
3.4
Median
4.0
4.0
3.0
As expected there is a strong positive relationship between the household size and the number
of loads of washing undertaken per week (see Figure 4-9). Because of the small sample sizes
for larger households, the six person or more households have been combined into one group.
29
Figure 4-9: Correlation between clothes washer use and household size.
Correlation between Clothes Washer Use and Household Size
10
y = 2.2104x0.7653
R2 = 0.9943
9
Avg No of Loads per Week
8
7
6.8
6.2
6
5.8
5
4.6
0.694
y = 2.0594x
R2 = 0.9634
4
3.2
3
2.0
2
ASUPS 2007
ASUPS 2003
1
0
1
2
3
Household Size
4
5
6+
There are a number of points that can be made from Figure 4-9. Firstly the drop in the average
number of loads for 6+ person households relative to 5 person households is likely to be the
outcome of sample error. For this reason it is necessary to model the average usage for each
household size based on the sample data. In this way a more logical relationship between the
various household sizes can be represented.
The sample data can be modelled using a simple power function and the model for the 2007
survey can be represented as:
No. of Loads i = 2.0594* HHi0.694
Where Loads i is the number of loads for a household size of i and HHi is the household size.
Note that this model results in an overall average use of 4.1 loads per week when Yarra Valley
Water’s overall average household size of 2.73 is used.
Note also from Figure 4-9 that the downward shift in usage from 2003 (both sample and
modelled) is greater for larger household sizes possibly reflecting the contribution of economies
of scale to efficient behaviours in these households.
4.3.3 Behavioural Patterns for Clotheswashers
4.3.3.1
Clotheswasher Water Level, Load Size and Temperature
The proportion of loads using the automatically selected water level has increased to 37% from
28% in 2003 (see Table 4-12). This increase may reflect the increasing technological
sophistication of the appliances. A large proportion of loads are still washed at full water level
while the manual selection of medium water level appears to have grown out of favour. This
30
finding is consistent with both the lower average number of loads discussed in 4.3.2 above and
also with the “wash with full loads” message contained in various drought related
communications.
Table 4-12: Clothes Washer Water Level Selected.
% of
% of
Clothes Washer Usual Households
Households
Water Level Selected
2007
2003
Auto
37%
28%
Low
5%
6%
Medium
18%
26%
Full
40%
40%
Table 4-13 shows the breakdown of load size vs. selected water level. It may be observed that
79% of clothes washer loads are full loads with the corresponding water level selected at either
auto or full. This compares with the 64% full loads in 2003. The 2% of full loads operated at low
water level is of dubious veracity. The increase in preference for full loads is at the expense of
medium loads while the proportion of low loads has remained the same across the two
surveys.
Table 4-13: Water level vs. load size.
Water Level
Selected
Percentage of
Household Using:
Auto
High
Medium
Low
All Levels
Load Size
Full
Medium
Low
All Sizes
29%
39%
8%
2%
79%
7%
1%
10%
1%
19%
1%
0%
0%
1%
3%
37%
41%
18%
5%
100%
The majority of households (59%) typically elect to wash in cold water (see Table 4-14) with
another 38% normally choosing to wash in warm water. The increase in the share of washing
undertaken mostly in cold water from 53% in 2003 is statistically significant at better than the
95% level.
Table 4-14: Water Temperature Selected for Clotheswasher.
Water Temperature
% of
Selected in
Households % of Households
Clotheswasher
2007
2003
Hot
4%
3%
Warm
38%
44%
Cold
59%
53%
31
4.3.3.2 Machine Washing versus Hand Washing
The survey in 2007 found the incidence of hand washing to be relatively minor (Table 4-15). It
is difficult to compare these results with ASUP2003 because of the different phrasing of this
question. Nearly seven out of every 10 households do all of their laundry in a clotheswasher
rather than hand washing. Of the balance more than three quarters do 90% of their laundry in
the clotheswasher so hand washing of clothes is a very small end use of water.
Table 4-15: Machine Washing vs Hand Washing.
Proportion of Laundry
done with machine
%
All
90%
75%
50%
25%
None
68%
25%
4%
2%
1%
0%
Respondents were asked as to what level they filled the bucket, trough, bath or basin when
hand washing clothes. The results in Table 4-16 show an equal preference for the use of
bucket and laundry trough, the two most preferred containers. Households that hand wash in a
bucket tend to half fill it whilst those using the laundry trough are more likely to fill it to one
quarter. These fill patterns are broadly consistent with that found for ASUP2003.
Table 4-16: Hand Washing Method and Fill Level
Hand Wash Using
% of Households
1/4 Full
1/2 Full
3/4 Full
Full
Bucket
47%
15%
58%
19%
7%
Laundry Trough
46%
62%
34%
3%
1%
Bath
Bathroom Basin
2%
5%
na
na
na
na
na
na
na
na
In the majority of cases (70%) households that wash by hand never leave the tap running when
rinsing their clothes (see Table 4-17). Around one quarter of households that undertake hand
washing occasionally leave the tap running for rinsing.
Table 4-17: Leave Tap Running when Rinsing Clothes (Hand Washing)
Leave Tap Running
% of Households
Always
5%
Occasionally
24%
Never
70%
32
4.4 Dishwashers
4.4.1 Dishwasher Ownership and Frequency of Use
Fifty eight percent of the households were found to have a dishwasher in 2007, which is four
percent lower than in 2003. However this is not a statistically significant difference at the 90%
level of confidence and it is difficult to imagine the true population proportion for this parameter
decreasing. The 95% confidence limit for this parameter is (55%, 62%) and so it is assumed
that the apparent decrease in 2007 is more likely to be sampling error within this interval.
As was the case for clotheswashers water and energy star ratings for dishwashers were largely
unavailable with water ratings identified for only 14% of dishwashers (see Table 4-18).
Consequently there is insufficient data from which to make any reliable conclusions regarding
the efficiency of dishwasher appliance stock.
Table 4-18: Water & Energy Star Ratings - Dishwashers
Percent of Dishwashers
Star Ratings
Water
Energy
Up to 2.5 stars
4%
5%
3 to 3.5 stars
4%
7%
4 stars
2%
5%
4.5 stars
3%
5%
Unlabelled
85%
77%
Invalid/Missing
1%
1%
All Dishwashers
100%
100%
When asked about the frequency of use per week, 6% indicated that they did not use their
dishwasher at all. The response was 8% for the same question in 2003.
Owner occupied homes had a much higher penetration of dishwashers (62%) than rented
properties (35%). These figures were 71% and 17% in 2003. The doubling in penetration of this
appliance in rental properties over four years is surprising and may be due to sampling error
given only 119 rental properties were surveyed in 2007.
Average use of the dishwasher per week is 3.8 while this was 4.4 in 2003 (see Figure 4-10).
The most common use of the dishwasher is 3 times per week followed by daily while the
reverse was true in 2003. This represents a significant (>99% level) downward shift in
dishwasher use since 2003. As was the case for clotheswasher use this apparent decline in the
frequency of use could be drought related.
33
Figure 4-10: Frequency of dishwasher use.
Frequency of Dishwasher Use
30%
Average Freq: 3.8 per week
Std Deviation: 2.7
Median Freq: 3.0 per week
Relative Frequency
25%
20%
ASUP2007
ASUP2003
15%
10%
5%
0%
≤1
2
3
4
5
6
7
8
Uses per Week
The 95% confidence interval for the average number of washes per week is [3.5, 4.0].
34
9+
4.4.2 Behaviour Patterns for Dishwashers
Ninety percent of the households operated the dishwasher with a full load, down from 98% in
2003. Six percent used the dishwasher with half the load capacity in 2007 compared to 2% in
2003 who said that they ran them with medium loads. About half of respondents ran their
dishwashers on economy cycle 100% of the time, similar to that in 2003 (see Table 4-19).
The proportion of dishwashers having no economy cycle has halved from ASUP2003 and could
reflect the improvement in technological sophistication of the appliance.
Table 4-19: Dishwasher Use of Economy Cycle.
Dishwasher:
Use of Economy
Cycle
ASUP2007
ASUP2003
100% of the time
53%
55%
75% of the time
4%
2%
50% of the time
12%
6%
Never
No Economy Cycle
16%
6%
15%
31%
Half of the respondents said they rinsed their dishes in the kitchen sink prior to putting them in
the dishwasher. This proportion remains unchanged from 2003.
As in the case of clotheswasher there is a strong positive correlation between dishwasher use
and household size (see Figure 4-11). Overall, there has been a downward shift in the graph
compared to 2003.
The usage for each household can be modelled based on the sample data and this enables the
removal of seemingly anomalous sample outcomes such as the average usage of 6 person
households being less than that for 5 person households. The model for the 2007 survey is:
No. of Loads i = 1.647* HHi0.703
Where Loads i is the number of loads for a household size of i and HHi is the household size.
This model results in an overall average use 3.3 loads per week when Yarra Valley Water’s
average household size of 2.73 is used. This average number of loads is 21% lower than the
2003 modelled average of 4.2 loads per week.
35
Figure 4-11: Correlation between Dishwasher use & Household Size.
Correlation between Dishwasher Use & Household Size
8.0
Average Uses per week
7.0
0.521
y = 2.489x
2
R = 0.957
6.0
5.0
0.703
y = 1.647x
4.0
2
R = 0.978
3.0
2.0
ASUPS 2007
1.0
ASUPS 2003
0.0
1
2
3
4
Household Size
5
6+
4.5 Tap Use
4.5.1 Hand Basin
4.5.1.1 Hand Basin Location
Hand basins are commonly located in the bathroom or ensuite and to a lesser extent in a
separate toilet or powder room. The survey found the vast majority (91%) of hand basins to be
located in the bathroom or ensuite. On average there are 1.7 hand basins per household,
unchanged from 2003.
4.5.1.2 Flow Rate
In the case of hand basins only the typical flow rate (defined as the flow rate at which the tap is
normally used) was measured. Average measured typical flow rate for hand basin was found to
be 8 litres per minute (Lpm) with a median of 6 Lpm (see Figure 4-12). The corresponding rates
in 2003 were significantly lower at 4.9 and 5 Lpm respectively. As some of the flow rate
measurements were up to 30 Lpm, it is almost certain that some assessors measured
“capacity” flow rate rather than “typical” flow rate. In fact 22% of the measured flow rates
were above 10 litres per minute whereas virtually all typical flow rates in 2003 were measured
at 10 litres per minute or less.
Consequently the data in 2007 is considered less reliable than the 2003 results.
36
Figure 4-12: Distribution of Hand Basin Typical Flow Rate (Lpm).
Distribution of Hand Basin Typical Flow Rate
25%
Average: 8 lpm
Standard Dev'n: 6.5
Median: 6 lpm
ASUP2007
ASUP2003
Relative Frequency
20%
15%
10%
5%
0%
1
4.5.1.3
2
3
4
5
6
7
Typical Flow Rate (lpm)
8
9
10
≥ 11
Frequency of Hand Basin Use
The average frequency of hand basin use per capita per day is estimated at 3.5 with the
distribution as shown in Figure 4-13. In ASUP2003, the average was 5.5 times per person per
day. There has been a definite shift in frequency of use towards the low end.
In fact this decrease in frequency of hand basin use is so substantial that it is cause for
question. In 2003 some 31% of households used the hand basin less than or equal to 3 times
per capita per day. In 2007 this proportion increased to 50%.
One hypothesis is that some respondents estimated the frequency of use for the hand basin on
behalf of just themselves rather than on behalf of the whole household. This hypothesis can be
tested to some extent by comparing the outcomes for single person households. In 2003 the
average daily per capita frequency of use for 1 person households was 6.7. In 2007 this
average decreased to just 4.5 uses. Since this outcome is not influenced by any potential
“individual” versus “household” error it is concluded that the overall reduction found in
frequency of use in 2007 is in fact plausible.
37
Figure 4-13: Frequency of hand basin use (per capita per day).
Hand Basin Frequency of Use (per capita per day)
25%
Average : 3.5 (5.5 ASUP2003) per capita per day
Standard Deviation : 2.2 (2.7 ASUP2003)
Median : 3.0 (5.3 ASUP2003) per capita per day
20%
15%
ASUPS 2007
ASUPS 2003
10%
5%
0%
≤1
1-2
2-3
3-4
4-5
5-6
6-7
7-8
8-9
>9
Hand basin use (uses per capita per day)
4.5.1.4
Hand Basin Leaks
Only 2.1% of hand basin taps were reported to have a small leak. There were no reported
cases of medium or large leaks. In ASUP2003 1.3% of hand basin taps were found to have
leaks.
4.5.2 Kitchen Sink
The kitchen sink is mainly used for food preparation and hand washing of dishes. Both of these
functions can be undertaken either by running water or by filling the sink to a desired level.
4.5.2.1 Kitchen Sink Tap Flow Rate
Capacity flow rates were measured in case of the kitchen sink. Average capacity flow rate for
kitchen sink is estimated to be 15.2 Lpm while it was 19.4 Lpm in 2003. This decrease could
reflect the contribution of new homes which, from 1 July 2005, must be installed with taps
having flow rates within the range of 7.5 Lpm minimum and 9 Lpm maximum.
As Figure 4-14 shows there is wide variation around the mean. A notable feature when
compared to 2003 is the sharp drop in the relative percentage of houses with greater than 27
Lpm kitchen taps to about 6% from 16%. Also it is notable that a much larger percentage of
households (21%) had kitchen taps with flow rates less than or equal to 9 Lpm than in 2003
(10%).
38
Figure 4-14: Distribution of Kitchen Sink Capacity Flow Rate (Lpm)
Distribution of Kitchen Tap Capacity Flow Rate
25.0%
Average : 15.2 lpm (19.4 ASUP2003)
Standard Deviation : 9 lpm (8.2 ASUP2003)
Median : 14 lpm (20.0 ASUP2003)
Relative Frequency
20.0%
ASUPS 2007
ASUPS 2003
15.0%
10.0%
5.0%
0.0%
≤6
6-9
9 - 12
12 - 15
15 - 18
18 - 21
21 - 24
24 - 27
27 - 30
> 30
Capacity Flow Rate (lpm)
As shown in Table 4-20, 63% of kitchen taps are fitted with aerators compared to 48% in 2003.
In 2007, only 3% of taps were found to be fitted with flow control valves compared to 5% in
2003 but this device is difficult to elucidate as it depends on the self reporting of respondents. It
is clear from Table 4-20 that having an aerator or flow control device significantly reduces the
capacity flow rate of the tap.
Table 4-20: Incidence of aerators and flow control devices.
Kitchen Tap Fitted
With
Aerator
Flow Control Device
Aerator and Flow
Control Device
None
Not sure
All kitchen Taps
% of
Households
ASUP2007
63%
3%
Average
Capacity Flow
rate (lpm)
% of Households
ASUP2007
ASUP2003
14
48%
10
5%
Average
Capacity Flow
rate (lpm)
ASUP2003
19
11
5%
11
9%
12
23%
6%
100%
20
16
15
38%
na
100%
23
na
19
4.5.2.2 Hand Washing Dishes
On average, dishes are hand washed 7.7 times per week which is unchanged from the 2003
survey. Households without a dishwasher hand wash dishes an average of 10 times per week
while households with a dishwasher undertake the task 5.6 times per week on average.
39
Eighty four percent of households indicated that they always use the plug when hand washing
the dishes and another 5% use a plug at least sometimes. In total the 89% of households that
use a plug when hand washing dishes is slightly lower than the 2003 result of 92%. Eleven
percent of households said that they do not use a plug at all when hand washing dishes.
Eighty three percent of households indicated that they do not fill the kitchen sink by more than
half when hand washing dishes.
4.5.2.3
Cooking
Across all households an average of 8.7 cooked meals per week was prepared at home,
slightly higher than the average 8.2 per week in 2003. A little over half (53%) of the households
prepared 5 to 7 meals per week with another fifth preparing between 10 and 15 meals.
Fifty nine percent of households indicated that they rinse food under a running tap which is little
changed from the 57% in 2003.
4.5.2.4
Leaks
About 4.4% of the kitchen taps were found to have small leaks while only 0.4% were found to
have either medium or large leaks.
4.5.3 Laundry Trough
4.5.3.1
Flow Rate
In general, the tap capacity flow rate of the home laundry trough is much higher than for other
household taps. Average laundry trough tap capacity flow rate in 2007 is estimated at 20.2 Lpm
compared to 25.7 Lpm in 2003 (see Figure 4-15). This decrease could reflect the contribution
of new homes which, from 1 July 2005, must be installed with taps having flow rates within the
range of 7.5 Lpm minimum and 9 Lpm maximum.
Whilst the incidence of flow control valves in laundry taps was found to be low (3%) forty
percent of taps are fitted with an aerator. The lower average capacity flow rate could also result
from this high incidence of aerators but this aspect was not investigated in the 2003 survey so
cannot be confirmed.
4.5.3.2 Leaks
About 4.9% of laundry trough taps were found to be leaking, significantly more than in 2003
when this figure was 1.7%. The leaks were assessed as small in 4.2% of households, medium
in 0.2% and large in 0.4% of households.
40
Figure 4-15: Distribution of laundry trough capacity flow rate.
Distribution of Laundry Trough Capacity Flow Rate (lpm)
20.0%
18.0%
Average Flow Rate: 20.2 (lpm)
Std Deviation: 11.1
Median Flow Rate: 18.0 (lpm)
16.0%
Relative Frequency
14.0%
12.0%
10.0%
8.0%
6.0%
4.0%
2.0%
>4
0
-4
0
36
-3
6
32
-3
2
28
-2
8
24
-2
4
20
-2
0
16
-1
6
12
-1
2
8
4
-8
0.0%
Capacity flow rate (lpm)
4.6 Baths
Baths were classified as standard/small, standard/large and standard/extra large whilst spa
baths were categorised as either small (max 2 people) or large. Usage questions covered
frequency of use and fill levels when in use by adults and children separately.
About 81% of the households surveyed had at least one bath and 10% had at least one spa
bath. The majority of baths are either standard/small (61% of baths) or standard/large (26%).
Only 1% of households had the older style extra large baths.
About 10% of the households had a spa bath and out of most (about 7%) are small spa baths
(for two people or less).
4.6.1 Bath Use by Adults13
Bath use by adults is relatively infrequent with only 22% of households indicating that the bath
is used by an adult. For these households use of the bath averaged 0.8 times per week per
adult or 1.6 times per household. Across all households the average usage of baths by adults
is only 0.17 per week per adult or 0.35 per week per household.
74% of households with a bath had no use by adults compared to 84% in 2003. At present 13%
of the households with a bath had some adult use at least once a week compared to 9% in
2003.
13
For the purposes of this analysis “Adults” are defined as persons over 18 years of age.
41
On average the bath is only half filled when used by adults. 49% of adult users indicated they
half filled the bath whilst 22% and 29% either quarter or three quarter filled the bath
respectively.
4.6.2 Bath Use by Children.
Children were found to use the bath in just 21% of households although this represents more
than half of the households with children less than 18 years of age. The average weekly usage
per child in households where the bath was actually used was 2.4 times per week per child
whereas this figure was 2.7 in 2003. The overall average number of baths per child per week
across all households with children under 18 yrs is 1.3 whereas this figure was 1.4 in 2003.
Use of the bath by households with children is highly correlated to the age of the children in the
household as Table 4-21 below demonstrates. Bath use by households with children under 3
years of age is the most common with over three quarters of these households using the bath
an average of 3.3 times per week per child.
Table 4-21: Incidence of Bath Use in Households with Children
Average Baths
Average Baths % of Homes
Households with
per Child
per Child /
using the
Children Aged:
where bath is
week
Bath
used
2.5
76%
3.3
0 to 3 years
3 to 12 years
1.2
62%
1.9
12 to 18 years
0.4
29%
1.5
All Homes with
Children
1.3
54%
2.4
The average fill level for the bath when used by children is significantly lower than when used
by adults. Fifty seven percent of households where children used the bath only quarter filled the
bath and another 34% of these households only half filled the bath. These figures were 60%
and 36% in 2003 respectively.
4.7 Evaporative Air Conditioners.
The percentage of households with an air conditioner increased to 73% from 66% in 2003 (see
Table 4-22 below). Ownership of evaporative air conditioners has risen to 27% of homes in
2007 compared to 20% in 2003. This is a statistically significant increase at the 99% level.
The share of refrigerated and reverse cycle air conditioners did not change significantly so all
the gain in ownership since 2003 occurred in the evaporative type which now make up 37% of
air conditioners.
42
Table 4-22: Type of Air Conditioner
Type of Air Conditioner
% of Households
Reversed Cycle
26%
Refrigerated
19%
Evaporative
27%
All Types
73%
Respondents were asked to estimate the average daily usage of their air conditioners on hot
days with the results shown in Figure 4-16 below.
Figure 4-16: Air Conditioner Usage by Type.
Air Conditioner Hours of Use on Hot Day
50%
45%
40%
Relative Frequency
35%
30%
25%
Evaporative
Other Types
20%
15%
10%
5%
0%
Less than 4 hrs
4 to 8 hrs
8 to 12 hours
More than 12 hours
Don’t' use it
The evaporative air conditioners on average are operated longer than the other types on hot
days with an approximate average14 of 6.2 hours versus 4.7 hours for the other types.
When comparing current to 2003 data, there has been marked increase in the proportion of
evaporative air conditioners that were operated in the 4 to 8 hours category at the expense of
those operated less than 4 hours. A much larger proportion of refrigerated and reverse cycle air
conditioners were also operated between 4 to 8 hours in 2007, but this appears to be at the
expense of the 8 to 12 hours operation. This suggests that while high energy consuming air
conditioners are being operated less frequently, the reverse is true for evaporative coolers
which are low on energy use but high on water use.
It should be noted that in this case usage estimates required an ambitious level of recall by
respondents given that air conditioner use is limited to summer months and the survey was
undertaken in August to October.
14
Approximate average is based on the mid points of the ranges shown in Figure 4-16
43
5 Survey Findings - Outdoor Use
5.1 Water Restrictions
The current survey was carried out during a period under Stage 3a water restrictions when
watering of lawns was prohibited but limited garden watering was permitted twice a week. Even
numbered houses can water gardens on Saturdays and Tuesdays. Odd numbered hoses can
water gardens on Sundays and Wednesdays. No watering permitted on Mondays, Thursdays
and Fridays. Manual dripper systems can be used between 6 am - 8 am on the watering days.
Hand-held hoses fitted with a trigger nozzle, watering cans and buckets can be used to water
gardens between 6 am – 8 am on the watering days. Households with at least one resident
aged 70 years or over may water their gardens manually on specified watering days between 6
am - 8 am or 8 am - 10 am.
The frequency of watering and to some extent the methodology used to irrigate is therefore
limited by the current drought restrictions. Consequently respondents were asked indicate their
frequency, duration and choice of irrigation methodologies in the present conditions and what
they believed would be the case when restrictions are not in place. These two aspects were
investigated for each of three major components of garden irrigation namely
− Garden (ie garden beds)
− Vegetable Garden
− Lawn
5.2 Property Types
There is a strong relationship between the type of property and water usage largely as a result
of the relationship between property type and garden usage. Table 5-1 below shows the
breakdown of the ASUPS sample by age and type of properties. More than three quarters of
the sample falls into the category of separate houses over 10 years old.
Age of the
property
Table 5-1: Property Type by Age ASUP2007
Separate
House
Semi
detached
terrace or
town house
Flat Unit or
Apartment
All
0-5 yrs
4%
1%
2%
7%
5-10 yrs
5%
2%
1%
8%
10+ yrs
76%
4%
5%
85%
All
85%
7%
8%
100%
The average annual usage for each of the cell categories from Table 5-1 are shown in Table
5-2 below. The relationship between property type and average usage is statistically significant
at better than the 99% level. The relationship between age of property and annual usage is
almost significant at the 95% level. The average annual usage of properties less than 5 years
44
old (138 KL) is significantly lower than the average for properties over 5 years of age (169 KL).
This could be indicative of smaller average lot sizes, gardens not yet established, more efficient
appliances (5 star homes) or a combination of all 3 factors.
Age of the
property
Table 5-2: Average Annual Usage (KL) by Property Type and Age
Semi
Detached
Average Annual
Separate
Terrace
or
Flat, Unit or
Usage (KL) quarter
House
Townhouse
Apartment
All
ending Sep 07
0 - 5 yrs
162
114
97
138
5 - 10 yrs
193
170
116
177
10+ yrs
175
115
103
168
All
176
130
104
167
5.3 Garden Configuration
5.3.1 Type of Garden
Assessors together with respondents classified garden type into four different categories
namely Traditional, Native/water conserving, Combination and Not sure. The results are shown
in Table 5-3 below.
Overall 91% of properties have some type of garden. 37% of all properties have traditional
gardens i.e. with lawns and garden beds. This is a significant decrease from the roughly 50% in
the 2003 survey. However, the shift has not been to native/ water conserving gardens which, at
22%, is short of the roughly 25% in 2003. Nine percent of homes surveyed had no garden
compared to 7% in 2003. The combination style of garden has gained ground since the 2003
survey.
Table 5-3: Garden Type by Dwelling Type.
Outdoor Garden
Type
Relative Frequency of Households
by Garden Type by Property Type Separate House
Semi detached
terrace or town
house
Flat Unit or
Apartment
Total
Traditional
32%
3%
2%
37%
Native/Water conserving
19%
1%
1%
22%
Combination
27%
2%
1%
30%
Not Sure
2%
0%
1%
2%
No Garden
5%
1%
3%
9%
Total
84%
7%
8%
100%
45
5.3.2
Garden Extent
Table 5-4 below indicates that 85% of properties that have a garden have both a front and back
garden while balcony gardens are rather rare possibly reflecting the absence of apartment
buildings in the ASUPS sample (residential dwellings over two storeys make up only 1.5% of
Yarra Valley Water’s dwelling stock).
Table 5-4: Garden Type by Location
Outdoor Garden
Type
Relative Frequency of Households by
Garden Type by Garden Location
Front & Back
Front
Back
Court Yard
Balcony
Total
Traditional
35%
3%
2%
1%
0%
41%
Native/Water conserving
19%
2%
3%
1%
0%
24%
Combination
30%
2%
1%
1%
0%
34%
Not Sure
1%
0%
0%
0%
0%
1%
Total
85%
7%
6%
3%
0%
100%
5.4 Garden Beds
5.4.1 Garden Beds - Irrigation Frequency
On average under stage 3a restrictions garden beds are irrigated 1.3 times per week. About
32% of households with gardens reported that they do not water them at all (see Figure 5-1
below). This is significantly greater than in 2003 when 10% of households with gardens did not
irrigate them. Most of those who do irrigate their gardens now undertake the task once (25%)
or twice (31%) per week in keeping with Stage 3a restrictions which permits only two watering
days per week. There is little to be gained from comparing the frequency of irrigation with the
2003 survey because of the different restrictions regimes in place.
About 10% of households with gardens indicated they currently water more frequently than
twice per week and it is hoped that they do so with non potable water. Further analysis reveals
that 98% of this group either used greywater (80%) or had a rainwater tank connected to
garden (20%).
46
Figure 5-1: Frequency of Garden Irrigation – All Properties
Frequency of Garden Irrigation - All Properties
Under 3a Water Restriction
35.0%
32.4%
Relative Frequency of Households
31.3%
30.0%
25.2%
25.0%
20.0%
15.0%
10.0%
7.3%
5.0%
1.3%
0.5%
1.3%
0.7%
0.0%
1
2
3
4
5
6
Garden Watering - Number of Times per Week
7
Do Not
Water
A higher proportion of native/ water conserving gardens (38%) are not watered compared to
traditional gardens (29%) but the difference is not as large as would be expected (see Table
5-5 below). When asked about the watering patterns in the absence of water restrictions
analysis of data shows still 30% of native/water conserving gardens are not watered compared
to 24% of traditional gardens. About 16% of the former are watered more than twice a week
compared to only 9% of the latter. This suggests that either garden types are not well
categorised or there is more irrigation than necessary on native/ water conserving.
Tenancy is a major determinant in relation to garden irrigation with some 34% of owner
occupied households reporting that they do not water their gardens at all compared to 87% of
rented properties under stage 3a restrictions.
Table 5-5: Watering Frequency by Garden Type – All Households.
Outdoor Garden
Type
Relative Frequency of Irrigation by
Garden Type: No.Times per week
1
2
3 or More
Do Not Water
Traditional
21.6%
39.7%
9.4%
29.4%
Native/Water conserving
25.9%
19.5%
16.2%
38.4%
Combination
Not Sure
29.8%
15.8%
31.8%
5.3%
10.2%
0.0%
28.2%
78.9%
Total
25.2%
31.3%
11.1%
32.4%
Respondents were asked how often they would water their gardens in the future if restrictions
were removed with results shown in Figure 5-2 which is strikingly similar to Figure 5-1. On
average the garden would be watered 1.8 times per week. It is significant that about 26%
47
stated that they would not water even if restrictions were lifted, only slightly less than the 32%
who do not water under current restrictions. Adding to this the 9% of properties that do not
have a garden then in total 35% of residential properties would not be irrigating their garden in
an unrestricted environment. This is significantly higher than in the 2003 survey where only
15% of households did not irrigate their garden.
A relatively small proportion would increase their watering frequency from once or twice per
week to three times a week. Hence, it is possible that water restrictions will effect a permanent
change in outdoor water use.
Figure 5-2: Frequency of Garden Irrigation – All Properties
Frequency of Garden Irrigation - All Properties
Under No Water Restriction
30.0%
26.6%
26.3%
Relative Frequency of Households
25.0%
20.0%
19.3%
17.3%
15.0%
10.0%
5.0%
4.2%
5.0%
1.0%
0.3%
0.0%
1
2
3
4
5
6
Garden Watering - Number of Times per Week
7
Do Not
Water
5.4.2 Garden Beds - Irrigation Duration
As shown in Figure 5-3 fifty seven percent of respondents who water their gardens do so for 15
minutes or less. Twenty five percent of them water for half an hour. The longer watering times
could correlate with the use of dripper systems but the questionnaire did not elucidate this
point.
The overall average watering time for garden irrigation is around 28 minutes15. It is not possible
to make a direct comparison for this average duration with the 2003 survey where duration was
estimated separately for each irrigation methodology. However the 2007 average duration is
close to the average duration found for hand held hose in 2003 of 25 minutes.
Overall average durations are approximate given that respondents are estimating their irrigation duration at
intervals of between 15 and 30 minutes. That is the choices are 15mins, 1/2hr, 3/4hr, 1hr, 11/2hrs, 2 hrs and
greater than 2 hrs.
15
48
Figure 5-3: Duration of Garden Watering
Duration of Garden Irrigation
60%
56%
Relative Frequency
50%
40%
30%
25%
20%
9%
10%
5%
2%
2%
1 1/2 hr
2 hr
0%
15 mintues
1/2 hr
3/4 hr
1 hr
Duration
5.4.3
Garden Beds - Irrigation Methods
Respondents were also asked how they would undertake garden irrigation when restrictions
were lifted and not surprisingly a lot of irrigation is transferred away from watering cans or
buckets to sprinkler systems (see Figure 5-5 below).
Figure 5-5: Share of Garden Watering by Watering Method (No Restrictions)
Respondents were asked to estimate the share of their garden watering that was undertaken
with each of the following irrigation methodologies:
− Watering Can/Bucket
− Hand Held Hose
− Drip Irrigation system
− Manual Sprinkler system (not allowed under Stage 3a restrictions)
− Automatic Sprinkler system (not allowed under Stage 3a restrictions)
Only 72% of households (n=612) indicated they currently water their garden and of these 72%
used just the one method. Just over one quarter (26%) used 2 methods whilst only 1.3% of
irrigators used three methods.
Currently the most common methodology is watering can or bucket with 39% of households
using this as their sole watering method. The other dominant method at present is hand held
hose which is the sole watering method for a further 28% of households. Only 5% of irrigators
use drip systems as their sole means of watering.
49
Figure 5-4 below summarises how respondents allocated their irrigation time across the three
irrigation methods available under Stage 3a water restrictions. There are only two standout
methods which are can/ bucket or hose.
Figure 5-4: Share of Garden Watering by Watering Method (Stage 3a)
Garden Watering Method Under 3a Water Restriction
45.0%
Percent of Irrigating
Households
40.0%
35.0%
30.0%
25.0%
20.0%
15.0%
10.0%
5.0%
0.0%
%
75
Drip Irrigation
-
0%
10
Hose
5
%
-7 5
0%
%
25
Can or Bucket
%
50
to
%
25
s
les
or
Respondents were also asked how they would undertake garden irrigation when restrictions
were lifted and not surprisingly a lot of irrigation is transferred away from watering cans or
buckets to sprinkler systems (see Figure 5-5 below).
50
Figure 5-5: Share of Garden Watering by Watering Method (No Restrictions)
Garden Watering Method - No Restrictions
Percent of Irrigating Households
35%
30%
25%
20%
15%
10%
Automatic Sprinkler
5%
Manual Sprinkler
0%
%
75
Drip Irrigation
Hose
%
00
-1
%
75
%%
50
50
to
s
%
les
25
or
%
25
Can or Bucket
However under no restrictions the hand held hose remains the dominant irrigation method for
gardens with 37% of irrigators indicating they do all of their watering with this method and
another 24% using the hose to a lesser extent.
Even in an unrestricted environment 14% of households said they would do 100% of their
garden watering with bucket/watering can compared to 8% each for manual and automatic
sprinkler systems.
Collectively however unmanned systems (drip, manual and auto sprinklers) make up a
substantial part of garden irrigation with 25% of irrigators indicating they would do between 75
and 100 percent of their watering using these methodologies.
5.5 Vegetable Garden
One quarter of homes have a vegetable garden mostly classified as small in size and
concentrated in separate houses (see Table 5-6 below).
51
Table 5-6: Vegetable garden size by type of dwelling
Outdoor
Garden Type
Relative Frequency of Households
by Vegetable Garden Size by
Separate House
Property Type
Semi Detached
Terrace or
Townhouse
Flat Unit or
Apartment
Total
0%
4%
21%
Large
5%
0%
Small
23%
10%
7%
No Vegetable Garden
73%
90%
93%
75%
Total
100%
100%
100%
100%
5.5.1 Vegetable Garden – Irrigation Frequency
Under Stage 3a, only 9% of vegetable gardens are not watered compared to 38% of garden
beds (see Table 5-7) with most watered twice or less per week in accordance with Stage 3a
allowances. Overall vegetable gardens are watered an average of 2.1 times per week.
If restrictions were to be lifted, watering frequency would increase to an average of 2.8 times
per week with just over half watering twice per week or more.
Table 5-7: Vegetable Garden Watering
Under Stage 3a
Under No
Restriction
Once per Week
21%
11%
Twice per Week
46%
28%
Three or more per week
24%
51%
Did not water
9%
9%
Average Times per Week
2.1
2.8
Frequency of Watering
5.5.2 Vegetable Garden – Irrigation Duration
The majority (77%) of vegetable gardens are watered for 15 minutes or less (Figure 5-6 below)
reflecting their predominately small size. The overall average watering time for vegetable
garden is 21 minutes.
52
Figure 5-6: Duration of Watering the Vegetable Garden
Duration of Watering the Vegetable Garden
90%
80%
77%
Relative Frequency
70%
60%
50%
40%
30%
20%
15%
10%
5%
3%
0%
1%
1 1/2 hr
2 hr
0%
15 mintues
1/2 hr
3/4 hr
1 hr
Duration
5.5.3
Vegetable Garden – Irrigation Methods
Of those households that irrigate their vegetable gardens most use the watering can/ bucket or
hose methods (see Figure 5-7). 80% of irrigators use a single method with 38% using only a
watering can/bucket whilst 36% irrigate solely with a hose. Only 13 of the 179 households who
irrigate a vegetable garden utilise drip irrigation with 8 of these households choosing this as the
sole irrigation method.
If restrictions were to be lifted there would be a substantial switch away from cans/ buckets to
hoses and sprinklers (see Figure 5-8 below). Over 85% of irrigators would use just a single
method and for those households 595 of the time that method is hose.
Forty seven percent of irrigators would use the hose as there sole irrigation methodology with
another 20% using it to a lesser extent. Even without restrictions watering can/bucket would be
the sole method chosen by 17% of irrigators whilst a total of 14% would choose either drip
systems or sprinkler systems as the sole method of irrigation.
53
Figure 5-7: Vegetable Garden Watering Method by Watering Time – Under 3a
Vegetable Garden Watering Method Under 3a Water Restriction
Percent of Irrigating Households
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
%
75
Drip Irrigation
%
00
-1
Hose
%
75
%50
%
25
to
Can or Bucket
%
50
%
25
or
s
les
Figure 5-8: Vegetable Garden Watering Method by Watering Time –No Restrictions
Vegetable Garden Watering Method Under No Water Restriction
Percent of Irrigating Households
60%
50%
40%
30%
20%
Automatic Sprinkler
10%
Manual Sprinkler
0%
%
75
%
00
-1
Drip Irrigation
Hose
%
75
%50
%
25
5
to
Can or Bucket
0%
%
25
or
s
les
54
5.6 Lawn
Seventy five percent of homes have lawns with 39% of them considered large and the rest
considered small16 (see Table 5-8). As expected, the incidence of lawns in separate houses at
82% is significantly higher than the incidence in “Other” dwellings where only 36% have a lawn.
Table 5-8: Lawn size by Type of Dwelling
Outdoor Garden
Type
Households by Lawn Size by
Property Type
Separate House
Semi Detached
Terrace or
Townhouse
Flat Unit or
Apartment
Total
Large
33%
3%
3%
29%
Small
48%
39%
29%
46%
No Lawn
18%
58%
69%
25%
Total
100%
100%
100%
100%
5.6.1 Lawn – Irrigation Frequency
Lawn watering is not permitted under Stage 2 and higher restrictions. Nearly 65% of
respondents reported that they would not water their lawns even if restrictions are lifted (Figure
5-9). Although no comparative figure is available from ASUP2003, this appears to be a
significant behaviour change).
Figure 5-9: Intended Lawn Watering Frequency – No Restrictions
Lawn Watering Frequency - Under no Water Restriction
70.0%
64.6%
Percent of Households
60.0%
50.0%
40.0%
30.0%
20.0%
16.8%
11.5%
10.0%
4.3%
1.9%
0.2%
0.0%
0.7%
5
6
7
0.0%
1
2
3
4
Number of Times per Week
Do Not Water
The size of lawn was not measured but rather classified into the two categories of “large” and “small” on the
judgment of each assessor.
16
55
5.6.2 Lawn – Irrigation Duration
Only 31% of households (263) responded to the question of duration of lawn watering. The
overall average duration is 22 minutes with the majority indicating they would water their lawn
for only 15 minutes (see Figure 5-10).
Figure 5-10: Duration of Lawn Irrigation (No Restrictions)
Percent of Irrigating Households
80%
Duration of Lawn Irrigation
72%
70%
60%
50%
40%
30%
20%
20%
10%
2%
3%
2%
0%
0%
1 hr
1 1/2 hr
2 hr
> 2hours
0%
15 mins
5.6.3
1/2 hr
3/4 hr
Duration
Lawn – Irrigation Methods
The methods chosen to water lawns are summarised in Figure 5-11 below which shows that
the majority of lawn irrigation is undertaken with the hose and sprinkler systems. Considering
sprinkler systems together around 45% of irrigators do between 75% and 100% of their
watering with either of these appliances. A further 37% do between 755 and 100% of their lawn
irrigation with the hose.
Just over 89% of irrigators would use just the one method to water their lawn with about half of
those using some type of sprinkler system and around 35% using the hose.
56
Figure 5-11: Intended Lawn Watering Method – No Restrictions
Lawn Watering Method - No Restrictions
40%
Percent of Irrigating
Households
35%
30%
25%
20%
15%
10%
Automatic Sprinkler
5%
Manual Sprinkler
0%
7
5%
00
-1
Drip Irrigation
Hose
%
5
%
-7 5
0%
2
5%
to
50
Can or Bucket
%
25
%
or
s
l es
5.7 Garden Survival Under Drought Restrictions
Respondents were asked to indicate on a 5 point sliding scale how well their garden and lawn
survived during the drought. The scale was labelled “Died” at one extreme and “Survived Well”
at the other extreme and the three remaining points were unlabelled.
Figure 5-12 below shows that the majority of households consider that their gardens have
survived the drought with some 86% indicating a ranking of middle or above. Just 4% of
households considered that their garden had died as a result of the drought.
Conversely the ranking for the lawn condition was centred more towards the left hand scale
with over one fifth (22%) of household’s indicating that their lawn had lawns died (see Figure
5-13 below).
57
Figure 5-12: Survival of Garden during the Drought
How Well The Garden Survived During The Drought
40%
Percent of Households
35%
32%
29%
30%
24%
25%
20%
15%
10%
10%
5%
4%
0%
Died
<---- 5 Point Sliding Scale---->
Survived
Well
Figure 5-13: Survival of Lawn during the Drought
How Well The Lawn Survived During The Drought
40%
Percent of Households
35%
30%
25%
22%
20%
19%
20%
13%
15%
11%
10%
5%
0%
Died
<---- 5 Point Sliding Scale---->
58
Survived
Well
5.8 Other Garden Practices
5.8.1 Mulch
Fifty seven percent of homes with gardens mulch annually with the balance about evenly
divided amongst those who never mulch and those who mulch every couple of years (see
Table 5-9). Tenanted properties are significantly less likely to mulch than owner occupied
properties.
Table 5-9: Use of Mulch by Property Type
Mulch Use (% of
Homes with
Gardens)
Never Mulch
Mulch Annually
Mulch every couple
of years
Total
Owner
17%
59%
24%
100%
Tenant
46%
38%
16%
100%
% All
21%
57%
23%
100%
While 57% of homes mulch their gardens annually 21% do not mulch at all. Homes with
traditional gardens are no more likely to mulch than native/ water conserving gardens but
combination gardens are marginally more likely to practise mulching compared to both these
types of gardens (see Table 5-10).
Table 5-10: Garden Type by Mulching Frequency
Garden Type
Percent of Households by Garden Type
Never Mulch
by Mulching Frequency
Mulch
Annually
Mulch every
couple of
years
Total
Traditional
24%
54%
22%
100%
Native/Water conserving
21%
51%
27%
100%
Combination
14%
65%
21%
100%
Not Sure
56%
33%
11%
100%
Total
21%
57%
23%
100%
5.8.2 Garden Tap Timer
A relatively small proportion of homes reported use of garden tap timers and nearly half will
never buy one (Table 5-11). Tenants are less likely to use the device compared to property
owners and a greater proportion of them expressed no intention of ever buying one.
A fairly large proportion of householders indicated they had a tap timer (18%) but never use it
which probably reflects the prohibition of unmanned watering under Stage 3a drought
restrictions.
59
Table 5-11: Use of Garden Tap Timers by Property Type
Use of Tap
Timer
Use all the time
Use
Have Tap Timer
occassionally but Never use
Owner
10%
7%
Tenant
0%
All
9%
May buy one
Never buy one
19%
15%
49%
3%
15%
14%
68%
7%
18%
15%
51%
5.8.3 Garden Rain Sensor
Use of garden rain sensors is relatively rare with only 5% of households using one (Table
5-12). Negative perception of the device is high with two thirds of property owners and over
three quarters of tenants indicating they would never buy a rain sensor.
A sizeable percentage of households (11%) indicated they have a rain sensor but never use it.
This possibly reflects the ban on use of automatic sprinkler systems under Stage 3a
restrictions.
Table 5-12: Use of Garden Rain Sensors by Property Type
Garden Rain
Sensor
Use all the time
Use
occasionally
Have one but
never use
May buy one
Never buy one
Owner
4%
1%
11%
17%
66%
Tenant
1%
0%
8%
13%
78%
All
4%
1%
11%
17%
68%
5.8.4
Garden Soil Moisture Sensor
Use of garden soil moisture sensor is very rare with only 1% of households using these
occasionally (Table 5-13). Negative perception of the device is high amongst both tenants and
property owners. Surprisingly 11% of households indicated they had moisture sensor but never
use it.
Table 5-13: Use of garden soil moisture sensor by owner/ tenanted properties.
Garden Soil
Moisture Sensor Use all the time
Use
occasionally
Have one but
never use
May buy one
Never buy one
Owner
0%
1%
12%
16%
71%
Tenant
1%
0%
8%
12%
79%
% All
0%
1%
11%
16%
72%
60
As with rain sensors 11% of households indicated they have a moisture sensor but never use it
and this too may be a possible outcome of Stage 3a restrictions.
5.8.5 Rainwater Tanks
Rainwater tank ownership has risen to 19% of dwellings in 2007 compared to 7.4% in 2003
though only 2.6% are connected to both toilet and garden (Table 5-14). The great majority of
tanks are in owner occupied properties since only 3% of tenanted properties are bestowed with
tanks. However, the desire for a rainwater tank is high amongst owners and only slightly less
so amongst tenants.
Table 5-14: Ownership of Rainwater Tanks and Connection Type.
Percent of Households
Owner
Tenant
All
Don't have but would like
one
61%
54%
59%
Never want one
17%
43%
21%
Tank to Garden
18%
2%
16%
Tank to Toilet
1%
0%
1%
Tank to Garden and Toilet
3%
1%
3%
100%
100%
100%
Total
Smaller sized tanks tend to be more popular with only 34% of tanks larger than 2500 K (see
Figure 5-14). There appears to be a discontinuity in ownership of tanks in the range 1,000 to
1,500 KL for reasons that are unclear. The respondent was asked to provide the capacity of the
rainwater tank.
61
Figure 5-14: Distribution of Rainwater Tanks by Tank Capacity
Distribution of Rainwater Tanks by Tank Capacity
25%
Percent of Households
20%
15%
10%
5%
00
Ov
er
70
00
00
00
-7
0
65
60
00
-6
5
00
00
00
-6
0
55
50
Capacity (Litres)
00
-5
5
00
00
00
-5
0
45
40
00
-4
5
00
00
00
-4
0
35
30
00
-3
5
00
00
00
-3
0
25
20
00
-2
5
00
00
00
-2
0
15
0
00
-1
5
10
010
0
50
<=
50
0
0%
Figure 5-15 shows that 33% of the new homes built during the last 5 years had a rainwater tank
either connected to garden, toilet or both possibly reflecting the impact of 5 star home
regulations. This is a significantly greater penetration of rainwater tanks than in either of the
other age categories shown. Whilst 19% of homes built more that 10 years ago had a rainwater
tank this is not significantly different from the penetration in 5 to 10 year old homes.
Figure 5-15: Rainwater Tank Ownership by Property Age
Rainwater Tank Ownership by Age of the Property
35%
33%
30%
Relative Frequency
25%
20%
19%
15%
12%
10%
5%
0%
0-5 yrs
5-10 yrs
Age of the Property
62
10+ yrs
Whilst rainwater for the garden is the dominant use, homes with rainwater tanks built during the
last five years are significantly more likely to have their tank connected to both toilet and
garden (see Table 5-15).
Table 5-15: Rainwater Use by Property Age
Rainwater Use by Age
% Tanks to
% Tanks to
of Property
Garden
Garden & Toilet
63%
37%
0-5 yrs
88%
13%
5-10 yrs
83%
17%
10+ yrs
81%
19%
All Homes with Tanks
5.8.6 Greywater
Anecdotally, the use of greywater has gained currency during water restrictions. Table 5-16
bears this out with only 29% of all homes reporting no greywater use. Most uses of greywater
are improvised, spread across bucketing in the shower, from the sink or washing machine while
permanent greywater systems are fairly rare (3% of households).
Tenants appear to be significantly less likely to use greywater than property owners, possibly
because they are less likely to water their gardens.
There are no comparative data on greywater use from ASUP2003.
Table 5-16: Use of greywater by property owners and tenants.
Use of Greywater Don't use
(% of households) greywater
5.8.7
Bucket in
Bucket in Water from
the
Bucket in the shower washing
shower the sink and sink
machine
Water from
washing
machine and Permanent
bucket in the greywater Total % of
sink/shower
system Households
Owner
25%
16%
0%
16%
16%
22%
4%
100%
Tenant
53%
9%
0%
9%
14%
14%
1%
100%
% All
29%
15%
0%
15%
16%
21%
3%
100%
Outdoor Swimming Pool
5.8.7.1 Incidence of Swimming Pools
Eight percent of the households had an outdoor swimming pool compared to 10% in 2003
(Table 5-17). The 95% confidence interval for this parameter is [6.2%, 9.8%] and the drop is
not statistically significant at the 90% level. Most pools are either large or medium; the size
distribution is fairly similar to the findings of ASUP2003.
Table 5-17: Swimming pool ownership.
63
Swimming Pool Ownership
5.8.7.2
% of
Households
None
92%
Large
Medium
(4-9 metres by 2-4 metres)
3%
Small
1%
Total
100%
4%
Use of Pool Cover
More than half of pool owners (57%) still do not use a pool cover, however use of pool covers
has increased steeply since 2003 when 71% were non-users (see Table 5-18).
Table 5-18: Use of swimming pool cover.
Use of Pool Cover
% of
Households
Never
57%
All year
31%
Summer
10%
Winter
1%
Total
100%
5.8.7.3 Topping Up Swimming Pools
Under Stage 3a restrictions, an existing residential pool may only be filled by means of a
watering can or bucket filled directly from a tap (and not by means of a hose). In 2003, only
1.5% of pool owners reported that they never top up their pools; this has increased to 21% in
2007 (see Table 5-19). Most pool top-ups are undertaken in summer as expected. The different
wording of this question in ASUP2003 makes a direct comparison difficult.
64
Table 5-19: Pool top up period.
% of
Households
ASUP2007
Pool Top Up Period
Never
21%
All year
12%
Summer
64%
Winter
3%
100%
Total
As shown in Table 5-20, over half of the pools are topped-up monthly. Comparison with
ASUP2003 shows significant behaviour change towards less frequent top-ups.
Table 5-20: Pool top up frequency.
% of
Households
ASUP2007
% of
Households
ASUP2003
Daily
4%
-
Twice a week
6%
3%
Weekly
11%
24%
Fortnightly
23%
40%
Monthly
57%
33%
Total
100%
100%
Pool Top Up Frequency
As shown in Table 5-21, use of rainwater to top up pool is significant with 45% using rainwater
combined with potable water delivered largely through the rainwater downpipe (Table 5-22).
These questions were not asked in ASUP2003.
65
Table 5-21: Source of water to top up pools
Source of Water to
Top Up the Pool
% of
Households
ASUP2007
Potable water
55%
Rainwater
26%
Both
19%
Total
100%
Table 5-22: Use of rainwater to top up pools.
Source of Rain Water to
Top Up the Pool
% of
Households
ASUP2007
Rainwater tank
24%
Rainwater downpipe
67%
Both
10%
Total
100%
66
6 Appendix A: Recruitment Letter
<date>
<NAME>
<ADDRESS>
<SUBURB>, VIC, <POSTCODE>
CUSTOMER ID:<CUSTOMER ID>
Dear <NAME>,
Re: 2007 Water Usage Patterns Survey
Yarra Valley Water periodically undertakes research into water use to assist us in planning.
The 2007 Water Usage Patterns Survey is a major research project that contributes to our
planning for water resources and helps ensure that our water conservation programs are
effective.
The survey involves our representative visiting your home to record what water using
appliances you have and how you use them. The representative will need to be at your home
for around an hour. In return for this commitment of your valuable time, you will receive a $40
Myer gift voucher. In addition, our consultant will issue you with a report showing how your
water usage compares with that of a water efficient household. Visits will occur during
weekends at a time suitable to you.
Please note that participation in this survey is totally voluntary. The information collected
from this survey will remain confidential and be used only for planning purposes. Individual
responses will be combined for analysis and no assessments or judgements of individual water
use will be included in this study.
If you would like to participate in this important survey there are three options you can
choose from - these are outlined over the page.
Yours sincerely,
Tony Kelly
MANAGING DIRECTOR
67
How can you participate in this important survey?
There are several ways you can register to take part:
Option 1:
If you have access to the internet, please register on the 2007 Water Usage Patterns Survey
link on Yarra Valley Water’s website. Visit www.yvw.com.au and click on the link “Saving
Water” and click on “Water Usage Survey 2007”. You will then be required to enter the
following information.
Username: water
Password: <Customer ID> (shown at the top of this letter).
Then you will be prompted to complete a short questionnaire to ensure that you qualify to
participate.
Option 2:
Call 1800 330 225 (free call) to register your interest. You will be prompted to leave your name,
phone number and customer ID number (shown at the top of this letter) and our representative
will contact you to confirm your participation.
Option 3:
If we haven’t heard from you through either of the above options, we may phone you to request
your participation. We appreciate that some customers do not like to be contacted for research
purposes, but ask for your understanding given the nature of this research and the importance
for sample households in the survey to be representative of Yarra Valley Water's customer
base. If you are contacted and do not wish to be involved in this survey or do not wish to be
contacted for any other research undertaken by Yarra Valley Water, then simply advise our
operator.
68
7 Appendix B: Appliance Stock & Usage Patterns Survey 2007 Questions
69
70
71
72
73
74
75
Outdoor cont…..
76