underground,
under threat
The state of groundwater
in England and Wales
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Foreword
The role of groundwater in providing
us with good clean water has long
been out of the public eye. But it is a
vitally important resource, providing
one third of the water we drink and
feeding many rivers and wetlands.
This summer’s drought has shown
just how much we depend on
groundwater, and the pressures that
it is under.
At the Environment Agency we aim to raise the profile
of groundwater and give priority to its protection and
management. In this report, our first on the state of
groundwater, we outline the uses of groundwater as
a water resource and then go on to look at the risks to
this resource from pollution and over exploitation.
At the end of the report we discuss how we manage
groundwater and the challenges that we face.
It is essential to plan now to secure the long-term health
of groundwater for both the environment and public
water supply. We will continue to look at groundwater as
part of the bigger picture of water management, and we
look forward to working in partnership with others to
protect this asset for future generations.
Paul Leinster
Acting Chief Executive,
Environment Agency
Environment Agency The state of groundwater in England and Wales
3
underground
The groundwater issue
Most of our water resources are
hidden beneath our feet as
groundwater. Out of sight, and out of
mind. To many of us that use it as a
water supply, groundwater remains
an unknown and under valued
natural asset.
There are two main threats to our groundwater
resource:
Demand
• If people take too much groundwater and levels
become too low, they might not be able to rely
so much on groundwater for their public water
supply. Many rivers and wildlife that depend on
groundwater might also be harmed or lost.
Pollution
• Groundwater is vulnerable to contamination and
difficult to clean if contamination occurs. It is
intimately linked to both surface water and soils,
so substances can get into groundwater from
either.
Groundwater provides clean, fresh water for our
homes, industry, agriculture and environment. It is
an integral part of the water cycle, linking rainfall to
rivers, lakes and seas. But this resource is limited, so
groundwater must be managed and protected so that
future generations can benefit from this renewable
resource.
4
Environment Agency The state of groundwater in England and Wales
The amount of groundwater we can use depends on
its accessibility and quality. It is especially valuable
because it is normally pure and so needs little
treatment. If groundwater is polluted, it may need
treatment before it is used. This could be too
expensive or too difficult to do and the resource
may be lost.
This report is published with our policy document,
Groundwater protection: policy and practice, which
explains how we will manage and protect
groundwater. In this report we look at the current
condition of groundwater. We give advance warning
of the challenges that we will face and the changes that
the Water Framework Directive will make necessary.
Most of the information that we have about
groundwater is based on the main aquifers used for
drinking water and most of these are in England (See
How does groundwater work? on page 7). This is
where we have concentrated our monitoring.
This means that we do not know as much about the
condition of groundwater in minor aquifers, many of
which are in Wales. Because of the limitations of the
data, we do not know yet what the major issues are
in Wales. We have been increasing our monitoring to
find out if there are more widespread problems.
under threat
Summary of the main issues affecting groundwater
Issue
Now
Future
Demand
Demand is high in some English regions. Everybody must use
water carefully to ensure demand does not continue to grow.
Potentially
increasing
Climate change
Winter recharge might be reduced if, as predicted, rain falls in
shorter heavier showers, but it could increase if winters are
wetter. Demand would also increase during more frequent
droughts.
Uncertain
Diffuse pollution comes from many small widespread sources.
This makes it difficult to control and even more difficult to
correct once it has happened. Nitrate is a particular problem.
Pesticides are being used more effectively, which means less
needs to be applied. Some pesticides have been banned; but
they must not be replaced by others that are even worse.
☺
Same
Urbanisation and large building developments can cause a
variety of problems – increased demand, reduced recharge
and further potential for pollution.
Worse
Diffuse pollution
Pesticides
Land use
Same
Environment Agency The state of groundwater in England and Wales
5
underground
Why do we care about
groundwater?
Groundwater provides us with a
range of benefits.
To human health
• People need a reliable supply of clean water to live.
Water companies abstract, treat and distribute
groundwater to the public.
• In England about one third of the public water
supply comes from groundwater, in Wales this
proportion is far lower, at around three per cent.1
• Groundwater feeds a large number of small private
supplies from springs, wells and boreholes. These
provide water supplies in rural areas not connected
to the public water system. These supplies are
particularly important in Wales and upland
England.
To the economy
• Industries and farms use groundwater, either from
the public supply or from private sources.
• Groundwater reserves are hugely important to the
economy. They are estimated to be worth about
£8 billion.
• The UK market for bottled water is growing fast
and is worth £1.7 billion a year. Each person in the
UK drinks an average of more than 30 litres of
bottled water every year.2 There are about 100
recognised natural mineral drinking waters in the
UK,3 nearly all of which come from groundwater.
6
Environment Agency The state of groundwater in England and Wales
To the environment
• Rivers are partly fed by groundwater and some are
almost totally dependent on it. The groundwater
part (or base flow) varies less throughout the year
than water running off the land surface,
so in the summer most rivers and their ecosystems
rely on groundwater to keep them flowing. Because
of this some public supply abstractions from rivers
actually come from groundwater.
• Springs and groundwater seepages can form
wetlands that support a unique ecology with
specially adapted plant and animal species.
Wetlands have other benefits too. They can help
control flooding by retaining and slowly releasing
surface water. They can also filter out sediments,
nutrients and toxic substances, which prevents
pollution of downstream rivers, but makes wetlands
particularly vulnerable to contamination.
under threat
How does groundwater work?
Groundwater comes from rainfall that has filtered
down through the ground and is stored in permeable
rocks, known as aquifers (Figure 1). The amount of
water aquifers receive (known as recharge) varies
throughout the year. Recharge rates and water levels
are lowest in the summer and early autumn, when
there is less rain and higher temperatures. In these
conditions more water is evaporated at the surface
and plants take more water from the ground, so less
is available for recharge. Recharge rates are highest in
the winter and groundwater levels reach a peak in
early spring. Changes in groundwater levels lag
behind rainfall, and this allows springs and rivers to
continue to be fed by groundwater over the summer,
which in turn causes the groundwater level to fall
(Figure 2). Failure of winter rainfall over one or more
years can lead to shortages in groundwater.
Figure 1
The main aquifers in England and Wales are the
Chalk in the south and east of England, sandstone
in the west of England and Wales, and limestone
(Figure 3). Most water circulates slowly in the upper
100 or 200 metres of an aquifer. In some places it can
penetrate several kilometres below the surface,
although at this depth the water becomes too salty to
drink. Although at least 40 billion m3 of water is
contained in the top 20 metres of the two main
aquifers alone, over 16 times more than the total
capacity of all surface reservoirs in the UK, only some
of this is available to use.4
Groundwater flows through aquifers and out into
rivers, lakes and the sea. The water table usually
follows the shape of the ground surface above it, and
gravity causes water to flow from high to low areas.
Figure 2
Groundwater levels and rainfall, 1995 to 2005
The water cycle
Groundwater level:
Above average
Below average
Rainfall
cloud
High
Rainfall
outflow
to spring
infiltration
evaporation
groundwater
(saturated rock)
out
flow
river
uptake
by plants
to r
ive
r
outfl
impermeable rock
ow to
sea
Low
sea
saline
groundwater
1995
1997
1999
2001
2003
2005
Environment Agency
Environment Agency The state of groundwater in England and Wales
7
underground
Water flows through cracks and
pores in the rock and the flow speed
varies with geology and depth.
Groundwater samples can contain a
mixture of water of different ages.
Water that stays near the top of an
aquifer might only be underground
for a month, but some of the deepest
water is thought to be millions of
years old. Water in the Chalk in the
south east of England can be 20,000
years old, originally falling as rain
towards the end of the last Ice Age.4
The unsaturated soils and rock above
groundwater can protect it from
pollution. They often act as a filter,
sieving out harmful chemicals and
bacteria. But in some places
groundwater is closer to the surface,
so some contaminants do get
through. Natural processes that help
clean up groundwater, which take
days or weeks in rivers and lakes,
can take decades or centuries
in groundwater. This is partly
because water and pollutant
flow is so slow, but also because
microbial decay processes are slowed
down by a lack of oxygen and
nutrients, and low temperatures.5
Figure 3
Main aquifers in
England and Wales
Chalk
Sandstone
Limestone
UK Groundwater Forum
8
Environment Agency The state of groundwater in England and Wales
under threat
Balancing supply and demand
Many people rely heavily on
groundwater whether they know it or
not but groundwater systems also
support other animals, plants and
habitats.
The amount of water taken (or abstracted) from an
aquifer needs to be in balance with the rate of
recharge and the amount of water that plants and
animals in rivers and wetlands need to survive.
Critically low water levels could cause irreparable
harm to vulnerable and often rare habitats.
Replacement sources of clean water would also have
to be found for public supply, which would be
extremely costly.
In the future, water demand is set to increase,
particularly with the projected growth in the number
of homes being built.6 Changes in weather patterns,
as a result of long-term climate change, could cause
additional supply problems.
Supply and demand
In some parts of the country people take and use a lot of
groundwater. In the future groundwater is likely to be
under even more pressure from more homes being built
in the driest and most groundwater dependent areas.
It is tempting to think that the answer to water
shortages caused by new housing is to build more
reservoirs, but this is not always the right option in the
long term. The best alternative is to manage demand by
introducing water efficiency measures, controlling
leakage or installing water meters. But there are also
other ways to store and distribute large volumes of
water. Water could be transferred between water
companies, or aquifers that are not full to capacity can
be used as ready made underground reservoirs. This
takes advantage of a process known as aquifer storage
and recovery.7
• The average annual recharge to the main aquifers is
seven billion m3, and about 30 per cent of this is
abstracted at a rate of nearly 7 million m3 per day8
(Figure 4). Most of this is abstracted in the south east
of England. Only one per cent of the total is
abstracted in Wales9 (Figure 5). This does not mean
that there is spare groundwater. Any water abstracted
from the ground is water that will not reach rivers.
The Thames Gateway development
Almost 120,000 new homes are planned on land
either side of the Thames Estuary to the east of
London.15
• Building water efficient new houses will help delay
the need for extra water, but will not solve the
problem.
The issues:
• More households will produce more sewage and
waste. The risk of urban groundwater pollution will
increase. Existing sewerage networks and waste
water treatment works might not be able to cope.
• Water in the area is already scarce and
groundwater supplies are under pressure. More
water will be needed to support the new homes,
but it’s not clear where this water will come from
and finding it will be costly.
Developing the area will reduce infiltration to
groundwater, possibly reducing aquifer recharge.
Wetlands will also be lost.
Environment Agency The state of groundwater in England and Wales
9
underground
The Shropshire
groundwater
scheme
In dry periods groundwater can be pumped out
of aquifers into rivers to increase flow. There are
over 50 of these augmentation schemes in
England and Wales, usually used to protect the
river environment or to support abstraction from
the river downstream. We need to protect rivers
during periods of low flow, but it is important
that groundwater resources are not sacrificed to
preserve the more visible surface water reserves.
Figure 4
Groundwater replenishment and abstraction
Replenishment
Abstraction
Million cubic metres/year
5,000
4,500
1,500
1,000
500
Chalk
PermoTriassic
sandstone
Jurassic
limestone
Lower
Greensand
UK Groundwater Forum
The £20 million groundwater scheme began in
1982 and is being completed in eight stages as
water demands increase. When all phases are
complete an extra 225,000 m3 per day will be
able to be taken from the river for public supply,
enough water for more than 600,000 homes.17
Figure 5
Groundwater abstracted in 2003
Percentage of total abstracted
Wales 1%
Anglian 16%
Thames
25%
Total =
2,388 Mm3
Midlands 17%
South West
9%
North East 7%
Southern 20%
North West 5%
Environment Agency
10
The River Severn is a vital source of water for the
West Midlands. During dry spells water is
released into the river from two reservoirs, Lake
Vyrnwy and Llyn Clywedog, to increase the flow.
In exceptionally dry years this still may not be
enough water. Groundwater is then pumped into
the river from the sandstone aquifer that
underlies much of North Shropshire.
Environment Agency The state of groundwater in England and Wales
Based on weather patterns over the last 50 years
the groundwater scheme is likely be operated in
two out of every five years. In other years water
from the reservoirs will be enough to meet
demand.
under threat
Groundwater provides a significant
proportion of the public water
supply in some areas.
• In 2004/5 an average of about 150 litres per day
of water was supplied to each person in England
and Wales.10 Demand for water will continue to
grow unless we improve water efficiency. Water
companies need to make sure that leakage from
the public water system is kept as low as possible,
so the problem isn’t made worse.
Figure 6
Public water supplied
by groundwater
11%
• The south east of England is an area of particular
concern. It is a highly populated area with
relatively low annual rainfall. As a result, the
supply of water in the south east of England
is limited. Some parts have less usable water per
person than countries such as Syria.11 Many more
homes are due to be built in the area, putting even
more pressure on the water supply.
• Groundwater provides a significant proportion of
the public water supply in some areas. This varies
around England and Wales according to where the
aquifers are (Figure 6). In the Environment Agency
Southern region more than 70 per cent of public
water supply comes from groundwater.8
14%
North
West
North East
40%
37%
Midlands
3%
Anglian
Wales
35%
Thames
74%
Southern
30%
South West
Environment Agency
• Seventy eight per cent of abstracted groundwater
is supplied to households and businesses by water
companies. Industry (12 per cent), aquaculture
(five per cent) and agriculture (four per cent) also
directly abstract large volumes12 (Figure 7).
Figure 7
Estimated abstractions from groundwater by purpose
Other
Electricity supply
Private water supply
Agriculture
Fish farming etc
Spray irrigation
Mineral washing
Public water supply
Other industry
• In most Welsh aquifers, recharge is thought to
greatly exceed abstraction, but we have found
some areas (such as the sandstone in the Vale of
Clwyd) where groundwater appears to be at or
near its abstraction limit.13
Million litres/day
• Our assessment for the Water Framework Directive
showed that over a quarter of the groundwater
bodies in England and four per cent in Wales are
at risk of failing environmental objectives because
of abstraction pressures.14
8,000
6,000
4,000
2,000
1995
1997
1999
2001
2003
Environment Agency
Environment Agency The state of groundwater in England and Wales
11
underground
Climate change
Rainfall variation means that groundwater levels go
up and down naturally, but changes in long-term
weather patterns might mean that groundwater levels
change permanently. In the future we need to make
sure that we recognise these changes and find ways to
manage them.
• The volume of rainfall is predicted to increase, but
shorter winters will mean that it will fall more
intensely over a shorter period. Aquifers are
recharged most effectively by prolonged steady
rainfall, falling outside the plant growing season.
Rainfall delivered over a shorter period might lead
to a long-term reduction in recharge of some
aquifers. Droughts are expected to be more
common.
• The changing weather patterns could also be felt in
the environment. Lower groundwater levels can
disrupt vulnerable and rare habitats.
• Rising sea levels could also lead to a loss of
groundwater resources and ecological damage, as
seawater can mix with groundwater in low-level
coastal aquifers.
What happens when groundwater levels
are too high?
12
Groundwater flooding
Rising groundwater
During periods of prolonged high rainfall,
groundwater (which naturally flows towards lowlying areas) can rise to the surface and flood lowlying land and sub-surface structures. Groundwater
flooding is rarer than river or coastal flooding and
usually occurs in chalk areas.16 It can sometimes be
more disruptive and damaging than surface water
flooding, because it takes far longer for the water
to recede.
Groundwater flooding is a natural occurrence, but
the problem is complicated when areas that have
artificially low water tables due to past industrial
abstraction are developed. When this abstraction
stops, due to the decline of some industries,
groundwater rises to the previous natural level. For
instance, in London groundwater levels had fallen
to 90 metres below the surface by the 1960s.4 Since
then the rate of abstraction has declined and
groundwater levels have recovered. The rising
groundwater threatened to flood some parts of the
underground infrastructure. The only way to stop
this happening has been to increase abstraction
again, to keep the water table below foundations
and tunnels.
Environment Agency The state of groundwater in England and Wales
under threat
Groundwater pollution
Groundwater has deteriorated in
quality over the last 50 years and we
all need to take action now to stop
things getting worse.
Pollution from diffuse sources (rather than from
point sources, which are easier to identify and
manage) has been a problem for groundwater for
some time. Anything soluble which is put on the land
has the potential to get into an underlying aquifer, so
everybody needs to be careful about what they put on
gardens, roads and fields (Figure 8).
There is direct interaction between groundwater and
surface water. If groundwater is polluted, it can
threaten surface water supplies, river ecosystems and
wetlands. Contaminated public water supplies might
have to be closed and replaced, or undergo more
extensive treatment.
Towns and cities
Industry
Rural communities
leaking sewers
petrol stations
wat
er
tabl
e
public
water
supply
• Almost half of the groundwater supply is now
blended with cleaner water, treated or has been
replaced (Figure 9).18
• One hundred and forty six groundwater sources
have been closed since 1975 because of
groundwater quality problems. At least 425,000
m3 per day have been lost in licensed output from
the closures, about seven per cent of current
abstraction levels (Figure 10).18
• The capital investment required to maintain
drinking water quality is expected to be at least
£15 to £36 million every year. Problems with
groundwater quality cost the UK water industry
£754 million between 1975 and 2004.18
Figure 9
Public groundwater supply in the UK affected by pollution
Figure 8
Threats from pollution
runoff
road salt
What does it cost?
People drink lots of groundwater, but also pollute it.
Water companies pay for it to be cleaned and these
costs are passed on to water bills. Sometimes it gets so
polluted that the aquifer can’t be used any more, and
other sources have to be found.
contaminated land
oil storage
manure, pesticides
and fertilizer
ploughing
septic
tank
Nitrate
Blending
Treatment
Closure
Pesticides
Blending
Treatment
Closure
Other
Blending and
treatment
Closure
Volume (Ml/d) (cumulative)
4,000
3,000
landfill
2,000
groundwater flow
private
well
saturated rock
public water supply
impermeable rock
1,000
1975
1980
1985
1990
1995
2000
2005
2010
UKWIR
Environment Agency The state of groundwater in England and Wales
13
underground
Polluting substances
Diffuse pollution
Pollution that comes from many small sources (diffuse
pollution) is the main problem for groundwater.
Substances that are spread on land, or leak from
underground pipes or storage can contaminate
aquifers. The problem is widespread, and diffuse
pollution is hard to trace and prevent.
• Around 81 per cent of groundwater bodies in
England and 35 per cent in Wales are at risk of
failing Water Framework Directives objectives
because of diffuse pollution.14 Nitrate is the most
widespread pollutant in England, others include
pesticides, oil, solvents and potentially phosphate.
Nitrate
Nitrate is one of the most common groundwater
pollutants. It can come from widespread sources,
like fertiliser spread on farmland or leaking sewers.
It is a particular problem in the south, east and
midlands of England.
Other micro
Cryptosporidium
Pesticides
Nitrate
Number of sources
60
50
40
• Sixty per cent of groundwater bodies in England
and 11 per cent in Wales are at risk of failing
Water Framework Directive objectives because of
high nitrate concentrations.14
30
20
10
1975
1980
1985
1990
1995
2000
2005
UKWIR
14
• More than two thirds of the nitrate in groundwater
comes from past and present agriculture, mostly
from chemical fertilisers and organic materials.
Organic materials, such as manure or treated
sewage sludge, can be a valuable source of
nutrients and organic matter to soils. If too much is
applied, or is applied in the wrong place or at the
wrong time, it can get into and harm groundwater.
It is estimated that over 10 million tonnes per year
of organic material is spread on the land in the UK.
More than 90 per cent of this is animal manure,
the rest is treated sewage sludge, green waste
compost, paper sludge and organic industrial
wastes.
• Other major sources of nitrate are leaking sewers,
septic tanks, water mains and atmospheric
deposition. Atmospheric deposition of nitrogen
makes a significant contribution to nitrate inputs
to groundwater. A study in the Midlands
concluded that around 15 per cent of the nitrogen
leached from soils came from the atmosphere.19
Sources of atmospheric deposition of nitrate
include transport, power generation and farm
animals.
Figure 10
Groundwater sources closed due to pollution
Salinity
Misc point source
Hydrocarbons and solvents
Iron/manganese
• In 2004 almost 15 per cent of monitoring sites in
England (none in Wales) had an average nitrate
concentration that exceeded 50 mg/l, the upper limit
for nitrate in drinking water.8 To put the problem in
context, groundwater naturally contains only a few
mg/l of nitrate. Water with high nitrate levels has to
be treated or diluted with cleaner water to reduce
concentrations.
Environment Agency The state of groundwater in England and Wales
under threat
Pollution that comes from many small
sources (diffuse pollution) is the main
problem for groundwater.
Pesticides
Pesticides are used to control weeds and pests,
and can cause diffuse pollution. They can get into
groundwater if they are able to leach through the soil.
Some pesticides break down slowly, so will stay in
groundwater for a long time. Others break down
quickly, but some produce more toxic chemicals in
the process. Some pesticides have been banned from
use but we need to make sure that the replacements
are better for the environment.
• In 2004 we found pesticides in over a quarter of
groundwater monitoring sites, and in some cases
they exceeded the drinking water limit
(Figure 11). There is some evidence that pesticide
concentrations in groundwater are declining in
some areas.20 This improvement is likely to be the
result of a shift to pesticides that are used at lower
application rates, and more controlled use and
disposal in response to tighter legislation.
• Atrazine is a weed killer used mainly to protect
maize crops and in the past to maintain roads and
Figure 11
Pesticides in groundwater 2004
Pesticides > 1µg/l
Pesticides > level of detection
Atrazine
Simazine
Atrazine desethyl*
Propazine
Atrazine desisopropyl*
Trietazine
HCH delta
Bentazone
Metazachlor
Dieldrin
Pirimicarb
Terbutryn
0
10
20
Percentage of sites
30
railways. It has been a major problem, but since
the non-agricultural uses were banned in 1993,
concentrations in groundwater have gradually
declined. A complete ban on all use of atrazine
(and simazine, another pesticide) will be phased
in between 2005 and 2007. Banned pesticides can
remain a problem for many years after they were
last used.
Solvents, hydrocarbons, and fuel additives
Fuel, fuel additives and solvents can contaminate
groundwater under cities and industrial areas. Some
of these chemicals are quite new, so we do not know
how much of a problem they will be.
• Chlorinated solvents are widely used as degreasers
in the metal, engineering, electronics and leather
industries. They are denser than water, they
degrade slowly and are toxic at very low levels so
small amounts can pollute large volumes of
groundwater. There is widespread contamination
in the aquifers below our industrial cities.
• Groundwater can be contaminated by
hydrocarbons (such as oils and fuels) from
installations such as petrol stations that are not
properly installed or maintained. Hydrocarbons
can disperse in water and be transported over long
distances. MTBE (Methyl Tertiary Butyl Ether) is
often added to petrol to enhance engine
performance. MTBE is highly soluble and can
move through groundwater much more easily than
other components of petroleum. Fuel containing
MTBE can enter groundwater through accidental
spillage or from leaking underground storage, and
it can create odour and taste problems in drinking
water. Related substances like ETBE (Ethyl
Tertiary Butyl Ether) could start to have wide
spread use in petroleum replacement biofuels, with
similar risks to MTBE.
*Degradation products of atrazine
Environment Agency
Environment Agency The state of groundwater in England and Wales
15
underground
Sometimes harmful microbes can get into
groundwater from sewage sludge spread on
farmland and leaking sewers or septic tanks.
Microbes
Microbes like bacteria and viruses are often filtered out
of water before they reach groundwater by the
overlying soils and rocks. Sometimes harmful microbes
can get into groundwater from sewage sludge spread
on farmland and leaking sewers or septic tanks.
• Over the last five years 42 groundwater sources
have been identified to be at high risk from the
micro-organism Cryptosporidium, and shut down.
Nineteen Cryptosporidium treatment schemes were
installed over this period and there are plans for 54
more.18 Water companies routinely sample sites
where a significant risk of Cryptosporidium has
been identified. This costs around £20,000 per site
per year.
• Problems in groundwater are likely to be localised
and we do not routinely monitor for microbes.
Studies have found microbes from man-made
sources in aquifers below Birmingham and
Nottingham at depths of up to 90 metres.21
Salinity
There is a natural boundary where fresh and saline
groundwater meet in coastal aquifers. When fresh
water is pumped out, this boundary moves and
seawater is sucked into the aquifer. This can also
happen inland, with groundwater abstraction causing
saltwater to be drawn up from deep water aquifers. If
too much water is taken from a coastal aquifer, it can
eventually become too salty to drink.
• Since the mid 1970s 11 groundwater sources
belonging to water companies have been shut
down due to saline intrusion problems and 50 sites
belonging to industry and private abstractors.18
• Salt can get into groundwater from other sources,
such as salt spread on roads in winter washing into
the ground. This has increased over the past
decade and shows the impact that human activities
are having on groundwater (Figure 12).
16
Environment Agency The state of groundwater in England and Wales
• High levels of abstraction for public water supply
have caused saltwater intrusion in the chalk
aquifer near Brighton. The problem is being
successfully managed by using boreholes in
different places at different times of year.
In winter, more fresh groundwater is flowing
towards the sea, so boreholes near the coast can be
used and inland boreholes are rested. In summer,
saline intrusion is more likely so the inland
boreholes are used instead.
• Boreholes around the Mersey Estuary have also
suffered from saline intrusion. In the past industry
close to the estuary abstracted large volumes of
water from the sandstone aquifer underlying the
Mersey basin, causing saltwater intrusion. It has
become less of an issue since the 1970s, when the
problem was recognised and strategies were put in
place to control the problem, but it still needs
careful management.
Natural contaminants
Natural contaminants can also occur in groundwater.
As water flows through the ground the chemistry
changes as elements are released from the rocks.
In certain aquifers, iron, manganese, arsenic, fluoride
and radon are found at relatively high concentrations.
Dissolved radon can be released as a gas and
accumulate in confined spaces such as houses.
Things we are looking out for
There are hundreds of chemicals that could get into
groundwater. We look for substances that are not a
problem now, but that we think might be in the
future.
• Pharmaceuticals have been found in groundwater
in other countries, usually near landfills that have
been used to dispose of hospital or pharmaceutical
industry waste.22
under threat
• Caffeine is a natural stimulant found in coffee and
tea. It has been detected at low concentrations in
groundwater across England and Wales. It is
thought to have reached groundwater via septic
tanks and leaking sewers. Although the caffeine in
groundwater does not present any risk it does
highlight how vulnerable groundwater is from
human activities.
• Triclosan is an antibacterial agent that is added to
a large range of consumer products. Sixty to
90 tonnes are used every year in the UK. Its
widespread use may be a risk to the environment
and human health.23 It is present in small quantities
in sewage effluent and sewage sludge, and it has
been found at a small number of groundwater
monitoring sites. There is a risk that triclosan
could affect bacteria that help break down some
pollutants.
Percentage of sites above concentration threshold
56
52
48
1995
1997
1999
2001
Urbanisation
Nearly everybody lives, works and travels in towns
and cities. Inadequate or faulty drainage systems
mean that groundwater can be polluted by dirty
water running off roads and other surfaces, badly
connected drains, leaking sewers and spilled
chemicals, oil and fuel.
• Poor water and sewerage systems often make
groundwater quality worse in urban areas. For
example, in Nottingham around half of the nitrate
loading in groundwater comes from the leaking
water mains and sewerage system.24 Groundwater
can also infiltrate sewers and overwhelm sewage
treatment works.
• About 24 per cent of groundwater bodies in
England and 7 per cent in Wales are at risk of
failing Water Framework Directive objectives
because of diffuse urban pollution.14
Mining
Metal and coal mines can have a huge impact on
groundwater systems. While mining is happening
groundwater is usually pumped out in large
quantities. When mining and pumping stops the
rising groundwater can become contaminated. The
mine structures can also change groundwater flow
permanently.
Figure 12
Chloride in groundwater 1993 to 2004
1993
Polluted places
2003
• The main pollutants from mining are iron, zinc, lead,
cadmium and acidic water. These substances can
leach down into groundwater from spoil heaps, or
can contaminate the upper part of the aquifer as
groundwater levels (previously artificially lowered
by pumping) begin to rise. The impacts can remain
for hundreds of years.
Environment Agency
Environment Agency The state of groundwater in England and Wales
17
underground
• In 1994, it was estimated that abandoned coal mines
had polluted more than 400 km of rivers.25 This was
primarily due to the rise in contaminated
groundwater after pumping stopped, known as
rebound. Treatment schemes operated by the Coal
Authority clean up more than 170 thousand m3 per
day of polluted groundwater. This has cost more
than £30 million since 1997.
• Mines and quarries can physically disrupt the flow
of groundwater. Removal of the overlying
protective layers of rock and soil, or bypassing
them with tunnels or engineering works, can
provide rapid pathways for pollutants to
groundwater. Or the aquifer itself can be removed.
For example, in the Mendip Hills the important
limestone aquifer has been extensively quarried.
• Metal mining has caused high concentrations of
heavy metal pollutants in groundwater across
Wales, the south west and northern England.
When the polluted groundwater reaches rivers it
can severely impact on fish and other aquatic life.
For example, 20 per cent (108 km) of all river
quality objective failures in Wales have been
attributed to mining pollution. In Cornwall, we
treat more than 17,000 m3 per day of polluted
groundwater every day at the abandoned Wheal
Jane tin mine. This minewater would otherwise
pollute the River Fal with heavy metals.
• Minewater rebound threatens several drinking
water supply aquifers. In County Durham, the
Coal Authority has to pump out over 5,000 m3 of
groundwater each day to prevent minewater rising
up and polluting the source of Sunderland’s
drinking water. In some areas recovering
groundwater levels can cause surface flooding.
• Fifteen per cent of groundwater bodies in Wales
and six per cent in England are at risk of failing to
meet Water Framework Directive objectives
because of pollution from mining.14
Industry can leave behind land
contaminated by chemicals or radiological
material that can leach through soils and
rock and pollute groundwater.
18
Environment Agency The state of groundwater in England and Wales
under threat
Landfills
Many different types of waste go to landfill, so there
are lots of potential pollutants. They are only a
problem if the landfill they are in has not been lined
properly, or is badly maintained.
• Most modern landfills are highly regulated and
operated to high standards, posing little risk of
pollution to groundwater. Older and closed landfills
might cause localised contamination issues.
• All landfill sites are likely to have been sent exempt
radioactive waste, for example smoke detectors and
exit signs.27 As a result low levels of radioactivity are
commonly found in landfill leachates, but it doesn’t
often get into groundwater and any problems are
minor and local.
Contaminated land
Industry can leave behind land contaminated by
chemicals or radiological material that can leach
through soils and rock and pollute groundwater.
• The best estimates are that over 300,000 sites
have been used for activities that could cause
contamination.27 Examples of these sites are former
gas works and petrol filling stations.
• Of these around 33,000 sites require action, and
about 21,000 sites have received some action to
remove contamination or prevent harm from
contamination. Many of these sites could cause
groundwater pollution so work is being carried out
to prevent this.27
Sustainable Urban
Drainage Systems
(SUDS)
Sustainable Urban Drainage Systems are an
approach to drainage management in towns and
cities that try to mimic natural drainage patterns as
much as possible. These drainage systems can
intercept pollutants and reduce flood risk, and we
think that they should become a common feature
of urban design.
Surfaces in urban areas are usually impermeable to
water, so rates of infiltration (and therefore
recharge of underlying aquifers) are limited. SUDS
can help return water to groundwater by slowing
down rainfall runoff in soakaways, permeable
surfaces, ponds and wetlands. This could make
groundwater more vulnerable to pollution if the
scheme is not designed and maintained properly.
Environment Agency The state of groundwater in England and Wales
19
underground
How we look after groundwater
We set out our position on
groundwater in our publication
Groundwater protection: policy
and practice. The document presents
the legal and technical framework
in which we work, and provides
detailed and informed advice on
many groundwater policy issues.
There is a lot we already do to protect
groundwater resources.
The EU Water Framework Directive is a new piece of
legislation. Its aim is for all waterbodies (river, lakes,
estuaries, coastal waters and groundwater) to achieve
‘good status’ by 2015. The directive is likely to be
particularly beneficial to groundwater, as rivers, lakes
and groundwater are considered in an integrated way,
rather than in isolation. This is particularly useful
when trying to address the issue of diffuse pollution,
which is a significant pressure on groundwater that
has proved difficult to deal with.
We routinely monitor groundwater quality and level to
help us understand the condition of groundwater, and
ideally identify any problems before they become too
difficult to deal with. There are 7,300 groundwater
level monitoring sites (180 of these are in Wales), and
the number of quality monitoring sites has doubled to
3,500 since 1999 (280 of these are in Wales). We also
work with and advise others, such as development
planners and industrial groups, to identify
groundwater issues.
20
Environment Agency The state of groundwater in England and Wales
It takes a long time to clean up groundwater, so
people who manage groundwater need to assess the
cost and difficulty of tackling pollution over equally
long timescales. There are no quick fixes for
groundwater, but preventing harm in the short term
will protect the resource for years to come.
Groundwater regulation
As part of our regulatory role, we issue permits for
abstractions and for discharges to water and land and
have enforcement powers. Where possible, our
decisions and actions are risk based. We concentrate
on activities and operators that are most likely to
harm groundwater. We can refuse licences if, for
example, we believe they will cause erosion of
someone else’s existing abstraction rights or harm an
aquifer or a protected wetland.
The Water Framework Directive extends our role. We
will be able to refuse to license activities that are
likely to harm river, lake, estuary, coastal or wetland
environments, or are likely to cause saline intrusion
or other contamination of clean groundwater.
Land use
If people want to keep using groundwater in the
future, it is vital that the sources are protected. The
risk of pollution generally increases when a polluting
activity or release is close to the groundwater source,
so sources used for public drinking water supply need
protection zones. We have published detailed maps of
nearly 2000 protection zones.
Nitrate Vulnerable Zones (NVZs) have been created
to reduce nitrates entering groundwater by limiting
the amount of nitrogen applied to farmland. The
rules that govern the application of manure and
fertilisers to land in these areas have been in place
since the mid-1990s and are due to be revised soon.
under threat
As yet, there is no evidence that nitrate levels in
groundwater are declining, but we expect the changes
to take time.
There are a number of recent measures that will help
to deal with diffuse pollution from agriculture. These
include the Catchment Sensitive Farming scheme, the
Voluntary Initiative for controlling pesticides, and
reform of the European Union’s Common
Agricultural Policy. To deal successfully with nitrate
from agriculture, more fundamental land use changes
might be needed. Radical measures like converting
some arable land to forestry have been shown to
work in Denmark and Germany.
Economics
In the future economic instruments may need to be
used more. These are financial incentives and
sanctions that operate using market forces, to
encourage beneficial behaviour. We are carrying out
research to try to place an economic value on
groundwater. As water resources become scarcer,
either from climate change or increased use by
society, then the value of groundwater could increase.
This could encourage trading in groundwater and
people could manage groundwater better, knowing
that the costs involved to save water, or improve
quality, could be offset by selling it at a higher price.
Groundwater would become another asset to be
traded, bringing a greater awareness of its value.
There are no quick fixes for groundwater, but
preventing harm in the short term will protect
the resource for years to come.
Environment Agency The state of groundwater in England and Wales
21
underground
Groundwater in the future
Most people don’t think about groundwater very
much. But if we look after it carefully then it will
keep supplying clean water for many generations
to come. Some contamination is inevitable and we
must learn to deal with it. Solutions need to be a
realistic mix that meet the demands of society and
the economy as well as the environment.
We think
We must
We support
22
that with the possibility of less water
available in the future demand must be
brought under control and eventually
reduced. If groundwater pollution
continues then there will be even less
water available and water resources will
be put under even more stress.
protect vulnerable aquifers from
potential sources of pollution. Prevention
is better than cure; and that requires
continued investment. We need to ensure
that we have the right regulatory tools to
protect groundwater in the future.
the development of Defra and Welsh
Assembly Government’s water, soil and
land contamination strategies. We are
encouraged by the initiatives to protect
groundwater developed by some water
companies, farmers and others.
Environment Agency The state of groundwater in England and Wales
under threat
1
Defra, 2005. e-digest statistics about: Inland Water
Quality and Use (2003 data). Available at
www.defra.gov.uk/environment/statistics/inlwater/iwab
straction.htm
2
Food Standards Agency, 2006. Natural Mineral Water,
Spring Water and Bottled Drinking Water (England)
Regulations 2006. Annex E: Partial Regulatory Impact
Assessment. Available at
www.food.gov.uk/multimedia/pdfs/mineralwater2006pr
ias.pdf. Per capita consumption figure calculated using
estimate of UK population from the Office of National
Statistics available at www.statistics.gov.uk
16
Defra and Jacobs, 2004. Strategy for Flood and Coastal
Erosion risk management: Groundwater Flooding
Scoping Study (LDS 23) Final Report, vol 1 of 2.
17
Based on average water use of 358 litres per household
per day.
www.ofwat.gov.uk/aptrix/ofwat/publish.nsf/Content/wa
terandyoumarch2001
18
United Kingdom Water Industry Research, 2004.
Implications of changing groundwater quality for water
resources and the UK water industry, Phase III: Financial
and water resources impact. UKWIR, London, 70pp.
19
3
Food Standards Agency, 2005. Mineral Waters.
Available at
www.food.gov.uk/foodindustry/mineralwaters
Environment Agency, 2003. Investigation of the
atmospheric deposition of nitrogen into groundwater.
Environment Agency, Technical Report P2-079/TR.
Available at www.environment-agency.gov.uk
4
Downing R.A., 1998. Groundwater our hidden asset.
UK Groundwater Forum, Wallingford, 60pp.
5
Environment Agency, 2006. Groundwater protection:
policy and practice.
6
Environment Agency, 2006. Water demand and
availability. Environmental indicator available at
www.environment-agency.gov.uk/yourenv
7
Environment Agency, 2001. Water Resources for the
Future: a strategy for England and Wales. Environment
Agency, Bristol, 96pp.
8
Environment Agency data (2003)
20
Worrall, F., Besien, T., and Garthwaite, D., 2006 (in
prep). Pesticides in the groundwater of Southern England
1992–2000. J. Hydrol.
21
Environment Agency, 2001. Distribution of
microbiological contaminants in Triassic Sandstone
urban aquifers. Environment Agency, Technical Report
SP2-255/TR. Available at www.environmentagency.gov.uk
22
Environment Agency, 2000. Review of human
pharmaceuticals in the environment. Environment
Agency, STRP390. Available at www.environmentagency.gov.uk
9
Environment Agency data (2003), ‘Wales’ refers to
political Wales.
23
Environment Agency, Triclosan briefing note. Available
at www.environment-agency.gov.uk
10
Ofwat, 2005. Security of supply, leakage and efficient
use of water 2004–05 report. Ofwat, Birmingham.
Available at www.ofwat.gov.uk
24
Wakida, F. T. and Lerner, D. N., 2005. Nonagricultural sources of groundwater nitrate: a review
and case study. Water Research, 39, 3–16.
11
National Audit Office, 2005. Environment Agency;
Efficiency in Water management. NAO, report HC73,
2005–2006. Available at www.nao.org.uk
12
Environment Agency data (2003)
13
Environment Agency, 2001. Water Resources for the
future, a strategy for Wales. Environment Agency Wales,
Cardiff, 184pp.
14
From Water Framework Directive river basin
characterisation. The figure refers to the number of
groundwater bodies at risk or probably at risk of failing
to achieve their environmental objectives by 2015.
25
National Rivers Authority, 1994. Abandoned mines
and the water environment. NRA Water Quality Series
No. 14. HMSO, London.
26
Environment Agency, 2002. Metal Mines Strategy for
Wales. Available at www.environment-agency.gov.uk
27
Environment Agency, 2005. Indicators for land
contamination. Environment Agency, Science Report
SC030039/SR. Available at www.environmentagency.gov.uk
15
ODPM, 2005. Creating sustainable communities –
Delivering the Thames Gateway. Available at
www.communities.gov.uk
Environment Agency The state of groundwater in England and Wales
23
Would you like to find out more about us,
or about your environment?
Then call us on
08708 506 506 (Mon–Fri 8–6)
email
[email protected]
or visit our website
www.environment-agency.gov.uk
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