Archive:
(for archive/historical purposes, this document has not been updated)Index of contents:
Who are the Drinking Water Inspectorate? What do we do? What happens in an inspection? What are the standards? How good is our drinking water? What about failures to meet the standards? What about bacteria in drinking water? What about pesticides? What about lead? What about nitrate? What about iron? What about cryptosporidium? What should I do if there is a problem with my water supply? Where can I get more information on drinking water quality 1. Who are the Drinking Water Inspectorate?
We are a team of professionals with a wide range of experience and expert knowledge in all aspects of water supply. This includes chemistry, microbiology and engineering. On health matters, we get advice from the Government's Chief Medical Officer.
2. What do we do?
Our main job is to check that the water companies in England and Wales supply water that is safe to drink and meets the standards set in the Water Quality Regulations. Inspectors carry out what we call technical audits of each water company. These have two main parts:
- an annual assessment of the quality of drinking water supplied by the companies
- inspections of the individual companies
The assessment of water quality is based on information received regularly from the water companies. This information includes the results of the millions of tests made each year to see if the water meets the standards. We check the test results against the standards. We also carry out inspections to be sure that the results are reliable and give a true picture of the quality of the water supplied.
3. What happens in an inspection?
Inspections may cover many things such as checks 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 satisfactorily
- consumer complaints are handled properly
If we find something wrong, we take action to ensure that the company puts things right.
4. What are the standards?
The Government has set legal standards for drinking water in the Water Quality Regulations. Most of these come directly from an obligatory European Community Directive but some UK standards are more stringent. Most standards are based on World Health Organisation guidelines. The standards generally include wide safety margins.
A new European Community Directive has been agreed. It contains a few more stringent and some new standards. New regulations will be made by the end of the year 2000 to implement the Directive and most new standards will have to be met by the end of the year 2003. The Inspectorate has agreed the improvements to be made by each water company to meet these standards.
There are standards for:
- bacteria
- chemicals such as nitrate and pesticides
- metals such as lead
- the way water looks and how it tastes
5. How good is our drinking water?
Drinking water is of a very high quality.
In 1999 the water companies in England and Wales carried out approximately 2.8 million tests on drinking water samples of which 99.82% passed. This is better than in 1998 and a considerable improvement on 1992. The charts overleaf show the percentages of tests which passed the standards and also the figures for tests which failed to meet the standards.
6. What about failures to meet the standards?
We assess each failure: some are trivial or unlikely to happen again, so no further action is needed. Other failures will be put right by improvements already being carried out by water companies - these involve treatment works and distribution systems and altogether cost many hundreds of millions of pounds.
Any remaining failures will be addressed by us requiring water companies to carry out further improvements quickly.
The Inspectorate has a duty to require water companies to take any necessary action. We check that improvements are being completed on time.
7. What about bacteria in drinking water?
Disinfection kills bacteria in water. Chlorine has been used to disinfect drinking water for more than a hundred years. Not all bacteria are harmful - some are easily detected. These are useful for indicating whether or not there has been a disinfection failure, or, if there has been a burst main, whether "dirty" water could have got into the mains. In 1999 the standard for bacteria was met in 99.8% of water supply zones compared with 1998 when 99.4% met the standard. Whenever it is suspected that bacteria may have got into drinking water supplies the water company investigates immediately. Consumers may be advised to boil water to be on the safe side. If the sample was taken from a consumer's tap, and many are, then the problem may be no more than dirt on the tap. The company will advise the consumer what to do.
8. What about pesticides?
Traces of pesticides can be found in some drinking water. They come from their use by farmers, gardeners and highways authorities. The standard for individual pesticides is very strict. The levels found in drinking water are very low and will not harm health. Where necessary, water companies have been installing treatment to remove pesticides from drinking water. In 1999, almost all (99.99%) of the 641,000 tests carried out met the standard. The few failures were occasional minor exceedances across 2.2% of the zones. Pesticides have been virtually eliminated from our drinking water.
9. What about lead?
Lead is commonly found in the environment. It comes from a variety of sources including vehicle exhausts and pre-mid 1960s paint work and may be present in air, food, soil or water. In drinking water it mostly comes from the pipes in people's houses. We have a separate, free, leaflet which gives advice on how to reduce exposure to lead from drinking water. Lead can have a small effect on the mental development of children. It may also be a factor in behavioural problems.
Where necessary, water companies treat water to prevent it picking up lead from pipework. In 1999, the standard for lead was met in 90.9% of water supply zones compared with 89.3% in 1998.
10. What about nitrate?
This comes from fertilizers and too much nitrate can sometimes be harmful to very young babies. There is a safety margin built into the standard for nitrate so that even if it is breached babies' health is unlikely to be harmed. Where necessary water companies have been taking action to control nitrate levels in drinking water. The standard was met in 99.6% of zones in 1999 compared with 99.5% in 1998.
11. What about iron?
This is something which people complain about frequently because iron can discolour water. It comes from rusty water mains. Even if water looks a very reddish brown colour it is unlikely to harm your health.
The standard for iron was met in 81.1% of water supply zones in 1999, this is better than in 1998 when 78.6% of zones met the standard. The position should improve further. Water companies have major programmes in hand to replace or reline corroded mains. These improvement programmes will take a further 10 years to complete. The worst affected areas are being dealt with first.
12. What about Cryptosporidium?
Cryptosporidium is a small organism found in man and many other animals. It can cause a disease called cryptosporidiosis. In infected animals it multiplies in the gut, forming tiny spores called oocysts, which are excreted in faeces in very large numbers. Oocysts are very resistant to adverse conditions in the environment and can survive for months in clean water or moist cool soil.
When ingested by another animal oocysts can transmit the disease and set up a new cycle of infection. For humans water can be a source of the organism, as can food, milk and contact with animals, particularly lambs and calves, and other infected persons.
In humans, cryptosporidiosis is a diarrhoeal illness usually lasting about two weeks from which most people recover fully. It is not very common. However, in people who are severely immuno-compromised, such as those suffering from HIV infection, the disease is much more serious and is one of several reasons why such people should always boil all water before drinking, whether tap or bottled.
Well-operated water treatment works which include physical barriers such as filters will greatly reduce the risks of oocysts contaminating drinking water supplies. Recent expert advice to the Government agreed that this is the best form of protection. The Drinking Water Inspectorate keeps a watch on research being carried out around the world to ensure that best practice is being applied.
The Government has introduced new regulations requiring water companies to continuously sample and analyse daily for Cryptosporidium at water treatment works judged to be at risk. It is an offence for a water company to exceed a treatment standard for Cryptosporidium. The Inspectorate will check that water companies meet these regulations.
13. What should I do if there is a problem with my water supply?
Contact your water company. Enquiry and emergency numbers are listed under Water in your Telephone Directory.
OR contact your local OFWAT Customer Service Committee listed under Consumer Organisations in your Telephone Directory.
OR contact your Environmental Health Department of your Local Authority
OR contact us - our address is below.
We investigate complaints from consumers and incidents which affect or could affect drinking water quality. Our investigations of incidents can lead to water companies being prosecuted. We have another free leaflet about consumer complaints, investigating incidents and prosecutions called "Problems with your drinking water".
DRINKING WATER IS OF A VERY HIGH QUALITY
The Inspectorate's job is to make sure it stays that way.
14. Where can I get more information about drinking water quality?
If you would like more information about drinking water quality you can get it from:
Your water company's public record
You can see the record at one of the company's offices. Customer services staff will explain the result of tests and tell you what is being done to rectify any failures. You are entitled to a free copy of the record for the area in which you live. Alternatively, you can write to the company for details.
Your local authority
Water companies are required to give local authorities information about the quality of water supply in their areas.
Our Annual Reports
These are lengthy reports containing a great deal of detailed information about the quality of drinking water in England and Wales. They can be bought from The Stationery Office. You may be able to see a copy at a main library or at your water company's offices or on this website
Other Leaflets
- What Do We Do ?
- Chlorine, Smell, Taste
- Discoloured Water
- Lead in Drink Water
- Private Water Supplies
- Problems with your Drinking Water
- Water Hardness
- DWI Summary Reports on each water company
Printed versions of the above leaflets are available from us free of charge
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Drinking Water Inspectorate,
Floor 2/A1, Ashdown House, 123 Victoria Street, London, SW1E 6DE
Telephone : 020 7944 5956 - Facsimile : 020 7944 5969
E-mail: dwi_enquiries@detr.gov.uk
Updated 11 July 2001
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