Alternative water sources
for the future
Guide for residents - Issued: May 2013
As part of our responsibility to generations
to come, MidCoast Water is exploring
opportunities for the provision of water for
our region into the future. We have adopted a
Sustainable Water Cycle Management Strategy
Our Water, Our Future to guide us to ensure
our catchments are protected and our future
water needs are met.
There are three identified long term options for our future water
supplies – recycling, desalination and new water storages. Here we
outline what each of these options are and what they involve.
Recycling
There are two main types of recycling MidCoast Water is investigating.
Non-potable recycling is recycling that is not suitable for drinking and
sees the use of recycled water used for purposes such as irrigation of
parks, sporting fields and crops, domestic garden watering and toilet
flushing.
Indirect potable recycling is a process of recycled water mixed with
raw water, at the water source, such as the dam or aquifer prior to
final treatment for drinking. Water is extracted from the source and
processed for the supply in the usual manner, which ensures there are
many levels of treatment before the water enters the drinking water
supply.
Non-potable recycling
MidCoast Water is already undertaking a range of non-potable
recycling projects and provides recycled water for irrigation to local
farmers and to golf courses, sporting fields, cemeteries and schools.
This reduces the demand on drinking water for these uses.
Other opportunities under investigation include the installation of
‘third-pipe’ systems in new developments. These systems provide
recycled water to homes for use in toilets, laundries and gardens. The
term ‘third pipe’ refers to the additional pipe installed to each home,
along with the drinking water and sewerage pipes.
Non-potable recycling and sustainability
• Non-potable recycling may provide the following benefits:• Lower ongoing energy and financial costs, as effluent may be treated to a different standard.
Nutrients which would normally be removed during the treatment process prior to river or
groundwater release can provide a benefit for irrigation uses.
• Reduction in the volume of effluent released into rivers and groundwater
• Reduction in the volume of raw water extracted from river and groundwater sources,
providing enhanced protection of environmental flows and dependant ecosystems
However, the following impacts should be considered:• Requires significant infrastructure to provide pipeline to each house with a third pipe system
• Water efficient behaviour (such as reduced garden watering) will limit non-potable use
potential
Indirect potable recycling
There are a number of indirect potable recycling possibilities being investigated by MidCoast
Water.
The first option involves transferring highly treated effluent from wastewater treatment plants
at Taree and Wingham into Bootawa Dam, where it would mix with water pumped from the
Manning River.
Water sourced from the dam would be treated in the Bootawa Water Treatment Plant.
Similarly, highly treated effluent from Stroud and Bulahdelah wastewater treatment plant may
be transferred to the off-river bulk storage at Stroud and Bulahdelah.
Another option is to transfer highly treated effluent from the Hallidays Point Sewage Treatment
Plant to Nabiac, where it would be injected into the Nabiac Aquifer, at a point ‘upstream’
(referring to groundwater flow) from MidCoast Water’s borefield.
Water extracted from the Nabiac aquifer would be treated at a water treatment plant to be
built on site. Similarly, highly treated effluent from Hawks Nest sewage treatment plant may
be transferred to Tea Gardens and injected into the Tea Gardens aquifer, ‘upstream’ of MidCoast
Water’s borefield.
The treatment process used to purify effluent for drinking is similar to that used in esalination
plants, and produces a concentrated ‘waste’ stream which much be managed.
Indirect potable recycling and sustainability
Indirect potable recycling may provide the following benefits:• Reduction in the volume of effluent released into rivers and groundwater
• Reduction in the volume of raw water extracted from river and groundwater sources,
providing enhanced protection of environmental flows and dependant ecosystems
• Injecting water into an aquifer (also known as groundwater recharging) may help to offset
the impacts of extracting water.
However, the following impacts should be considered:• The ‘Yuck factor’ associated with drinking effluent
• The waste stream needs ongoing management to allow for no-harm return to the
environment
• Ongoing energy use is higher than that of a bulk-storage, but less than that of a desalination
plant.
Desalination
Desalination is the process of removing salts, minerals and other
contaminants from saltwater such as oceans and estuaries to produce
high quality drinking water.
What does it involve?
There are a number of desalination methods. Reverse osmosis, which is
the process of forcing salt water through a very fine membrane, is the
method MidCoast Water is investigating.
The membrane used is so fine, that while water is able to pass through,
salts, minerals and other contaminants cannot.
Estuarine desalination, which is the opportunity MidCoast Water
is investigating, involves the desalination of water from the upper
Manning Estuary, which is less salty than the ocean.
This process separates the water into two streams. One stream is the
purified, salt-free water for drinking. The second stream (the “waste”
stream) contains a high concentration of salt.
One concern that is often raised in regard to desalination is that
returning the concentrated waste stream to the estuary may cause
some localised environmental harm.
MidCoast Water would address this issue by extracting water from the
estuary, and using a sufficient volume to dilute the waste stream to a
concentration similar to that of the estuary.
Desalination and sustainability
Estuarine desalination may provide the following benefits:• Reduced reliance on freshwater sources
• Water supply is not dependant on rainfall
However, the following impacts should be considered:• High ongoing energy use (although lower than ocean desalination)
• The brine waste stream needs ongoing management to allow for
no-harm return to the environment
• Doesn’t encourage recycling and any increase in water consumption
will result in an increase in the volume of wastewater to be
managed
Off- river bulk storage
Bulk storages are often called dams, however, this name can be
misleading, as not all bulk storages require the damming of a river.
As the name suggests, an off-river bulk storage is a dam that is not built
across a river (similar to a farm dam), and therefore has a very reduced
impact on natural river flows.
What does it involve?
MidCoast Water currently has two such bulk storages; at Bootawa
and Stroud (MidCoast Water also has on-river storages at Stroud and
Bulahdelah).
The bulk storage is constructed by creating a wall of clay, earth and
rock, and is filled by pumping water from a nearby river when there
is adequate water available (in our case, this is the Manning River for
Bootawa, and the Karuah River for Stroud).
In times of low flow, pumping ceases, and the reserves in the
dam allow for continued provision of water to our customers until
conditions allow for the resumption of pumping.
If MidCoast Water were to build an additional off-river storage in the
Manning Valley, it would use the Manning River as the water source.
Desalination and sustainability
An off-river bulk storage may provide the following benefits:Low ongoing operating costs
• Diversified storage, allows for continuity of supply in the event of
failure of the other storage
• Large storage volume with minimal impact on a river
• Allows for varied extraction from river, helping to protect
environmental flows
• Once constructed they are expected to last for over 100 years
Low energy use
• Can provide security of supply during times of low-flow
However, the following impacts should be considered:• Loss of land that may be used for other purposes
• Requires a large amount of material to construct the dam wall,
which may require transportation to the site, depending on on-site
sources
• Requires extraction of a large volume of water for the initial filling of
the storage
• Doesn’t encourage recycling and any increase in water consumption
will result in an increase in the volume of wastewater to be
managed
For more information about MidCoast Water contact our Customer Service Centres
on 1300 133 455 or visit our website www.midcoastwater.com.au