Index of Contents:
- Introduction
- Coliform Bacteria
- Pesticides
- Lead
- Iron and Manganese
- Cryptosporidium
- Drinking Water Quality Incidents
- Further Information
1. Introduction
The Drinking Water Inspectorate (DWI) checks on behalf of the Government that water companies supply water that is safe to drink. This leaflet summarises the results of our checks on Three Valleys Water PLC during 2001. You should read it alongside DWI’s leaflet, How Good is the Drinking Water? which gives more details on the standards and tests. This is available free of charge and on the DWI web site at www.dwi.gov.uk..
Three Valleys Water continues to supply you with drinking water of a high quality. In 2001, 99.85% of more than 93,000 tests met the drinking water standards. This is close to the overall figure for England and Wales of 99.86%. The tests are carried out on samples taken from water treatment works, service reservoirs and consumers’ taps.
None of the failures of the standards in 2001 were considered harmful to consumers’ health. Each failure was assessed and, where necessary, Three Valleys Water has taken action to prevent further failures.
Although the 2001 results are good, there are some matters, which may concern you. These are detailed below including any steps taken by Three Valleys Water to further improve its performance.
2. Coliform bacteria
Occasionally, coliform bacteria may be found in drinking water samples; these are not considered harmful to consumers’ health. If coliform bacteria are detected, Three Valleys Water investigates immediately.
During 2001, low numbers of coliform bacteria were detected in the water leaving five water treatment works and eight service reservoirs. The standard at service reservoirs permits 5% of samples to contain coliform bacteria. In 2001, none of the company’s service reservoirs failed the standard.
DWI was concerned about the failures of the total coliform standard at one treatment works but the Company has taken remedial action at this works to prevent the failures recurring.Coliform bacteria were detected in 0.3% of the water samples taken from consumers’ taps. Many of these failures could be due to the condition of the tap and not the water itself. The standard permits 5% of samples in a water supply zone to contain coliform bacteria. In 2001, all zones met the standard.
3. Pesticides
Three Valleys Water carried out more than 5,000 tests for individual pesticides during 2001 and all but one sample met the stringent standard. This reflects the significant investment in recent years to remove pesticides from drinking water. At the very low concentrations found, the pesticides detected did not represent any risk to health.
4. Lead
Samples do occasionally fail the standard for lead, even where additional treatment has been installed to reduce the amount of lead picked up by water from pipework. These failures are usually due to the consumers’ water pipes being made of lead. Whenever a failure occurs, Three Valleys Water informs the householder of any problems and advises of any action that can be taken to reduce lead levels in the water at their tap.
If you are concerned about the possibility of lead in your drinking water, you should contact Three Valleys Water to see whether there is a problem. A leaflet about lead in drinking water is also available from DWI free of charge and can also be found on the DWI web site.
Only one of the 572 samples taken by Three Valleys Water failed the standard for lead during 2001.
5. Iron and manganese
These two parameters provide a good indication of the overall condition of the mains used to distribute drinking water throughout the area of supply.
During 2001, only 6 of the 2,051 samples taken for iron failed the standard. None of the 576 samples taken for manganese failed the standard. This reflects the impact of the programme of work being carried out by Three Valleys Water to renovate its distribution system. Three Valleys Water renovated 135km of water mains during 2000 and 2001. The improvement programme is ongoing, with Three Valleys Water being required to renovate a further 1,073km of mains by 2008.
6. Cryptosporidium
Cryptosporidium is a tiny micro-organism that can sometimes cause a form of diarrhoea called cryptosporidiosis. There are a number of sources of Cryptosporidium other than drinking water, New regulations require water companies to sample continuously and analyse daily for Cryptosporidium in the treated water at potentially vulnerable sites.
It is a criminal offence to exceed the new treatment standard for Cryptosporidium.
During 2001, Three Valleys Water fulfilled its requirement to carry out continuous sampling and monitoring at nine of its sites that were identified as being at significant risk from Cryptosporidium. The Company is required to tell DWI of any failures to meet the treatment standard. Three Valleys Water reported no failures during 2001.
In addition, as part of the new regulations, the Company is committed to programmes of work to reduce any potential risk from Cryptosporidium at 14 sites. Four of these programmes were completed during 2001.
7. Drinking Water Quality Incidents
DWI regarded 11 of the events notified during 2001 by the Company as incidents. The details are shown in the table below.
Each of the incidents, assessed by DWI, was of short duration and the company took remedial action. Five recommendations were made mainly regarding operations and maintenance of records.
Summary of water quality incidents reported in 2001
Type of incident
No.of incidents
Assessment completed
Areas affected
Supply of discoloured water
2
Yes
Epping, Ware
Contamination of supplies
5
Yes
Stevenage, Colesdale, West Horsley, Winkfield Barnet
Supply of water with objectionable taste & odour
2
Yes
Stapleford, Great Kingshill
Wholesomeness concerns
2
Yes
Finchley, Wraysbury
9. Further information
If you would like more information about drinking water quality the following leaflets are available free of charge from DWI and can also be found on the DWI web site:
What do we do?
How good is the drinking water?
Problems with your drinking water
Chlorine, smell and taste
Discoloured water
Lead in drinking water
Private water supplies
Water hardness
Tap water, where does it come from and how is it made safe to drink?
Using lead-free solder for drinking water fittings
DWI reports on each water company
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Drinking Water Inspectorate,
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Telephone : 020 7944 5956 - Facsimile : 020 7944 5969
E-mail: dwi.enquiries@defra.gsi.gov.uk
Published 10 July 2002
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