Archive:
(for archive/historical purposes, these documents have not been updated)Index of Contents:
- Introduction
- Bacteria
- Lead
- Iron and Manganese
- Cryptosporidium
- Drinking Water Quality Incidents
- Determinations in 1999
1. Introduction
The Drinking Water Inspectorate (DWI) checks that water companies supply water that is safe to drink when it reaches your home. This document summarises the results of our checks on Sutton and East Surrey Water plc during 1999 and should be read in conjunction with DWI's "How Good is the Drinking Water?" leaflet which is available here and also from us free of charge from the address at the end of this document.
Sutton and East Surrey Water continues to supply you with drinking water of a high quality. In 1999, 99.60% of more than 24,100 tests met the standards. This is below the overall figure for England and Wales of 99.82%.
None of the failures in 1999 were likely to harm consumers' health. We assessed each one and, where necessary, we have required Sutton and East Surrey Water to take action to prevent further failures.
Although the 1999 results are good, we know that there are some matters of everyday concern to consumers. These are detailed below including the steps taken by Sutton and East Surrey Water to further improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Sutton and East Surrey Water investigates immediately. No bacteria were found in water leaving any of the Company's treatment works in 1999. Low numbers of bacteria were detected on one occasion in the water leaving a service reservoir during 1999. The bacteria found were not harmful to consumers' health. There has been a significant decrease over the past three years in the number of samples from service reservoirs in which coliform bacteria were detected. The number of bacteriological failures at consumers' taps remains similar to recent years at 0.2% of the samples taken. Many of these failures may be due to the condition of the taps and not the water itself.
3. Lead
Samples 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. In many cases this is due to the consumer's pipework being made of lead. One sample in 1999 failed the lead standard and the householder was informed of the problem. The Drinking Water Inspectorate advises consumers living in properties with lead pipes to seek advice from their water company. A DWI leaflet about lead in drinking water is also available here and from us free of charge from the address at the end of this document.
4. Iron and Manganese
These two parameters provide a good indication of the overall condition of the mains used to distribute drinking water through the region.
Three samples failed the standard for iron, an improvement on 1998, and none failed the standard for manganese. This is an overall improvement and reflects the programme of work being carried out by Sutton and East Surrey Water to renovate its distribution system. The programme of improvement is ongoing, with Sutton and East Surrey Water being required to renovate more than 202km of mains by 2005.
5. 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 water but due to new regulations water companies are required by law to sample continuously and analyse daily for Cryptosporidium in the treated water at those sites which have a potential vulnerability. All water companies had to initially conduct risk assessments at their sites to determine if there was any significant risk of contamination. Sutton and East Surrey Water identified that there was significant risk at two of its sites and is now continuously sampling and monitoring the treated water. It is an offence if the new treatment standard for Cryptosporidium is exceeded. In addition to the regulatory requirement, the company is able to get early warning of any treatment problems from this monitoring system.
6. Drinking Water Quality Incidents
In February 1999 a failure in the disinfection system at the Company's Godstone treatment works occurred following re-installation of a computer programme at the works. The quality of the water leaving Godstone remained satisfactory. In mid-November a disinfectant-like taste and odour was present in the water supply to parts of Sutton. The cause remains unidentified although it is possible that backsiphonage occurred. Both incidents were of short duration and the Company took effective remedial action. In 1999 the Inspectorate completed its assessment of an incident in December 1997 in which an outbreak of cryptosporidiosis occurred in the area supplied by the Company's Elmer treatment works. Deficiencies at Elmer treatment works were identified and the Inspectorate made eight recommendations concerning Company's procedures which the Company has implemented.
7. Determinations in 1999
Parameter
Total
Contravening PCV No % Coliforms 1701 4 0.2 Faecal coliforms 1701 1 0.1 Colour 300 0 0.0 Turbidity 740 1 0.1 Odour 191 0 0.0 Taste 191 0 0.0 Hydrogen ion 1256 0 0.0 Nitrate 300 0 0.0 Nitrite 636 84 13.2 Aluminium 321 1 0.3 Iron 547 3 0.5 Manganese 110 0 0.0 Lead 1693 1 0.1 PAH 114 0 0 Trihalomethanes 181 0 0.0 Total pesticides 176 0 0.0 Atrazine 174 0 0.0 Other pesticides 2256 0 0.0 Tetrachloroethene 181 0 0.0 All others 3225 0 0.0 Total 15994 95 0.6
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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
Published 12 July 2000 / Updated 11 July 2001
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