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underground,under threat

The state of groundwaterin England and Wales

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future generations.

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and the ground you walk on. Working with business,

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The Environment Agency. Out there, making your environment

a better place.

Environment Agency The state of groundwater in England and Wales 3

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

Foreword

4 Environment Agency The state of groundwater in England and Wales

underground

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.

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.

The groundwater issue


Summary of the main issues affecting groundwater

under threat

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 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.

�Same

Pesticides 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

Land use Urbanisation and large building developments can cause a

variety of problems – increased demand, reduced recharge

and further potential for pollution.

� Worse


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.

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.

underground

Why do we care aboutgroundwater?


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.

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.

under threat

How does groundwater work?

groundwater

(saturated rock)

infiltration

outflow to river

outflow to seaimpermeable rock

uptakeby plants

river

sea

Rainfall

cloud

salinegroundwater

outflowto spring

evaporation

The water cycle

Figure 2

Groundwater levels and rainfall, 1995 to 2005

1995 1997 1999 2001 2003 2005

Above average

Below average

Rainfall

Environment Agency

Groundwater level:

High

Low

Figure 1


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

underground

Figure 3

Main aquifers in

England and Wales

Chalk

Sandstone

Limestone

UK Groundwater Forum


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.

under threat

Balancing supply and demand

The Thames Gateway developmentAlmost 120,000 new homes are planned on land

either side of the Thames Estuary to the east of

London.15

The issues:

• 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.

• Building water efficient new houses will help delay

the need for extra water, but will not solve the

problem.

• 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.

Developing the area will reduce infiltration to

groundwater, possibly reducing aquifer recharge.

Wetlands will also be lost.


underground

Total =

2,388 Mm3

Wales 1%

Anglian 16%

Midlands 17%

North East 7%

North West 5%Southern 20%

South West

9%

Thames

25%

Figure 5

Groundwater abstracted in 2003

Percentage of total abstracted

Environment Agency

Figure 4

Groundwater replenishment and abstraction

500

1,000

1,500

4,500

5,000

Chalk Permo-

Triassic

sandstone

Jurassic

limestone

Lower

Greensand

Replenishment

Abstraction

UK Groundwater Forum

Million cubic metres/year

The Shropshiregroundwaterscheme

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.

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.

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

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

• 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.

• 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

• 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).

• 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

• 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

14%11%

3%

30%

40%37%

35%

74%

North East

Anglian

Thames

Southern

South West

Wales

Midlands

North

West

Figure 7

Estimated abstractions from groundwater by purpose

Environment Agency

2,000

4,000

6,000

8,000

1995 1997 1999 2001 2003

Million litres/day

Other

Private water supply

Fish farming etc

Mineral washing

Other industry

Electricity supply

Agriculture

Spray irrigation

Public water supply

Figure 6

Public water supplied

by groundwater

Groundwater provides a significantproportion of the public water

supply in some areas.

Environment Agency


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.

Groundwater flooding

During periods of prolonged high rainfall,

groundwater (which naturally flows towards low-

lying areas) can rise to the surface and flood low-

lying 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.

Rising groundwater

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.

What happens when groundwater levelsare too high?


under threat

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.

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.

• 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

Groundwater pollution

landfill

public water supply

privatewell

public

water

supply

saturated rock

impermeable rock

groundwater flow

water table

Figure 8

Threats from pollution

Towns and cities Industry Rural communities

leaking sewers

petrol stations

runoff

road salt contaminated land

oil storage

manure, pesticides

and fertilizer

ploughing

septic

tank

Blending and

treatment

Closure

1975 1980 1990 20001985 1995 2005

UKWIR

Volume (Ml/d) (cumulative)

Figure 9

Public groundwater supply in the UK affected by pollution

Nitrate

Blending

Treatment

Closure

Pesticides

Blending

Treatment

Closure

Other

1,000

2,000

3,000

4,000

2010


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.

• 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.

• 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.

• 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

1975 1980 1990 20001985 1995 2005

UKWIR

Number of sources

Figure 10

Groundwater sources closed due to pollution

10

20

30

40

50

60

Salinity

Misc point source

Hydrocarbons and solvents

Iron/manganese

Other micro

Cryptosporidium

Pesticides

Nitrate


under threat

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

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

Figure 11

Pesticides in groundwater 2004

0 10 20 30

Atrazine

Simazine

Atrazine desethyl*

Propazine

Atrazine desisopropyl*

TrietazineHCH delta

Bentazone

Metazachlor

Dieldrin

Pirimicarb

Terbutryn

Percentage of sites

Pesticides > 1µg/l

Pesticides > level of detection

Pollution that comes from many smallsources (diffuse pollution) is the main

problem for groundwater.


underground

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).

• 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

Sometimes harmful microbes can get intogroundwater from sewage sludge spread onfarmland and leaking sewers or septic tanks.


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.

Polluted places

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.

• 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

Figure 12

Chloride in groundwater 1993 to 2004

48

52

56

1993 1995 1997 1999 2001 2003

Percentage of sites above concentration threshold


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• 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.

• 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.

• 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.

• 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 landcontaminated by chemicals or radiologicalmaterial that can leach through soils androck and pollute groundwater.


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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 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.

Sustainable UrbanDrainage Systems(SUDS)


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.

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.

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How we look after groundwater


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.

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There are no quick fixes for groundwater, butpreventing harm in the short term will protectthe resource for years to come.


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.

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Groundwater in the future

We think 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.

We must 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.

We support 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.


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

3 Food Standards Agency, 2005. Mineral Waters.

Available at

www.food.gov.uk/foodindustry/mineralwaters

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)

9 Environment Agency data (2003), ‘Wales’ refers to

political Wales.

10 Ofwat, 2005. Security of supply, leakage and efficient

use of water 2004–05 report. Ofwat, Birmingham.

Available at www.ofwat.gov.uk

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.

15 ODPM, 2005. Creating sustainable communities –

Delivering the Thames Gateway. Available at

www.communities.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 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

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.environment-

agency.gov.uk

22 Environment Agency, 2000. Review of human

pharmaceuticals in the environment. Environment

Agency, STRP390. Available at www.environment-

agency.gov.uk

23 Environment Agency, Triclosan briefing note. Available

at www.environment-agency.gov.uk

24 Wakida, F. T. and Lerner, D. N., 2005. Non-

agricultural sources of groundwater nitrate: a review

and case study. Water Research, 39, 3–16.

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.environment-

agency.gov.uk

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GEHO0906BLDB-E-P

Environment first: This publication is printed on paper made

from 100 per cent previously used waste. By-products from

making the pulp and paper are used for composting and fertiliser, for

making cement and for generating energy.

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

incident hotline 0800 80 70 60 (24hrs)

floodline 0845 988 1188

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