How Good is our Drinking Water?

Drinking Water quality

Drinking water quality in England and Wales is regulated by the government through the Drinking Water Inspectorate (DWI). The Inspectorate was set up in 1990 after the water industry was privatised to operate as an independent body with staff experienced in all aspects of water supply.

How the DWI works

The DWI's main task is to check that the water companies in England and Wales supply water that is safe to drink and meets the standards set in Water Quality (Water Supply) Regulations. To achieve this, DWI staff carry out technical audits of each water company. These audits comprise of two parts:

The checking of results of drinking water tests by the water companies; and
Visits to each water company to inspect specific aspects of

their operating practices. Drinking water quality is assessed on the basis of information provided by the water companies. Millions of tests are made each year to see if drinking water meets the standards set down in the law.

These tests are carried out at water treatment works, in the distribution systems and at consumers' taps in designated geographical areas called water supply zones.

The DWI checks the test results and carry out inspections to ensure that the results are reliable and give a true picture of the quality of the water supplied.

The DWI also investigates consumers' complaints and incidents that affect or could affect drinking water quality. Investigations of incidents can lead to water companies being prosecuted. A leaflet 'Problems with your drinking water' published by the DWI describes consumer complaints, investigation of incidents and prosecutions. This is obtainable free of charge from the DWI on request.

What does an inspection involve?

A typical inspection may include checks to ensure that:

sampling procedures are satisfactory
samples are tested by trained staff using accurate methods
the right numbers of tests are carried out

correct results are entered in the public record
appropriate water treatment processes are used
treatment processes and the water distribution system are operated and maintained with safety in mind
consumers receive sound advice and help with queries and concerns.

If problems are identified, the DWI takes action to ensure that the water company puts things right.

What are the standards?

The legal standards for drinking water quality in England and Wales are set down in the Water Quality Regulations. Most of these standards come directly from European law and are based on World Health Organisation guidelines. The UK Regulations include additional standards to safeguard the already high quality of water in England and Wales. The standards are strict and generally include wide safety margins.

They cover:

A European Community Directive which came into force in 1998 contains new standards and some changes to existing standards. New regulations were made at the end of 2000 to implement this new Directive and the water companies were required to meet the new standards by the end of 2003. Where this did not happen the DWI required the water company concerned to take immediate improvement actions.

How good is our drinking water?

Drinking water is of a very high quality. In 2003 the water companies in England and Wales carried out approximately 2.9 million tests on drinking water samples of which 99.88% passed. This is better than in 2002 and continues the trend of continuous year on year improvement. The charts below show the percentages of tests, which passed the standards and also the number of tests which failed to meet the standards.

Figures for percentages of tests passing the standards

Figures for the number of tests failing to meet the standards

How are failures to meet the standards dealt with?

Each failure is assessed. Some are not important in terms of health or are unlikely to happen again, so no further action is needed. Some failures will be rectified by improvements already underway at treatment works and in the distribution systems operated by water companies.

The DWI requires the water companies to deal with any remaining failures by committing to immediate improvements. As part of the inspection process, a check is made to ensure that all such improvement work is carried out in a timely and appropriate manner.

What might be found in drinking water?

Micro-organism and small traces of chemicals substances may occasionally be present in water.

Bacteria

Untreated water may contain bacteria, although these are not necessarily harmful. Disinfection kills bacteria in water. Chlorine is used to disinfect drinking water and has been used successfully for almost one hundred years. Water companies monitor the effectiveness of disinfection continuously and test for bacteria. When there is a risk of contamination for example, following a burst pipe consumers may be advised to boil water as a precaution while investigations are being carried out. In 2003, the standard for bacteria was met in 98.04% of water supply zones.

Cryptosporidium

Cryptosporidium is a micro-organism found in man and animals in many parts of the world. It can cause a disease called cryptosporidiosis. Water can be a source of the organism as can food, milk, contact with animals, particularly lambs and calves, other infected persons and swimming pools. The organism multiplies in the gut of infected people or animals forming tiny spores called oocysts, which are then excreted in faeces in very large numbers capable of transmitting the infection. Oocysts can survive for months in clean water or moist cool soil.

In humans, cryptosporidiosis causes diarrhoea usually lasting about two weeks. It is not very common, but in people with severely depressed immune systems, the disease becomes more serious. In such cases all water, whether tap or bottled, should be boiled before drinking.

Much has been learned about Cryptosporidium in water in the last few years. In 1999, the Government introduced new regulations to optimise water treatment and minimising the risk of Cryptosporidium contaminating drinking water. These regulations required water companies to assess each of their water treatment works for risk from Cryptosporidium.

From April 2000, the companies were required by law to continuously monitor the effectiveness of the treatment at those sites identified as potentially at risk. Water supplied from these sites has to meet a specific treatment standard for Cryptosporidium.

Regulation of Cryptosporidium in drinking water in England and Wales is now the most advanced in the world. The DWI experts

offer advice guidance on Cryptosporidium internationally.

Pesticides

Traces of pesticides can be found in some drinking water. When found, the levels are very low, are not harmful to health and are usually the result of pesticide usage by farmers, gardeners and highway authorities. Where necessary, water companies have been installing treatment to remove pesticides from drinking water. In 2003, 99.99% of over 800,000 tests carried out met the standard.

Lead

Lead in the environment comes from a variety of sources and may be present in air, food or water. Lead can affect the mental development of children and may also be a factor in behavioural problems. In drinking water it comes mostly from lead pipes that may be in some people’s houses. Where necessary, water companies treat water to prevent it picking up lead from pipes. A leaflet is available which gives advice on how to reduce exposure to lead from drinking water. In 2003, the standard for lead was met in 97.78% of water supply zones compared with 96.50% in 2002. A new and more stringent standard came into force in 2003, with an even tighter standard to be met by 2013. Water companies are continuing to work towards meeting these tighter standards.

Nitrate

Nitrate comes from fertilizers and may find its way into drinking water when it can sometimes be harmful to very young babies. A safety margin built into the drinking water standards for nitrate so that even if it is breached, babies' health is unlikely to be harmed. Water companies have been taking action to control nitrate levels in drinking water. In 2003, the standard for nitrate was met in 99.11% of zones, which is about the same as that achieved in 2002.

Iron

Iron can discolour water and the discolouration is often unacceptable to consumers. Iron occurs naturally in many water sources, but may also be derived from the corrosion of iron mains. Any discolouration of water by iron is unlikely to be harmful to health. The iron standard was met in 88.44% of water supply zones in 2003. This is better than in 2002 when 86.64% of zones met the standard. The position will improve further as water companies implement major refurbishment programmes in hand to replace or reline corroded mains. These improvement programmes will take a number of years to complete.

What if there is a problem with my water supply?

In the first instance, you should contact your water company. Enquiry and emergency numbers are listed under Water in your telephone directory. If you are unhappy with the water company’s response then:

Contact your local Consumer Council for Water (formerly WaterVoice) listed under Consumer Organisations in your telephone directory.

OR contact the Environmental Health Department of your local authority.

OR contact the DWI – the address is overleaf.

DRINKING WATER IN ENGLAND AND WALES IS OF A VERY HIGH QUALITY

The DWI works to make sure it stays that way.

Drinking Water Inspectorate

55 Whitehall, London SW1A 2EY

Telephone: 020 7270 3370 Internet e-mail: dwi.enquiries@defra.gsi.gov.uk Or on the Internet at http://www.dwi.gov.uk