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 Wessex Water Services Limited 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.
Wessex Water continues to supply you with drinking water of a high quality. In 1999, 99.89% of more than 158,700 tests met the standards. This is above 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 Wessex 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 Wessex Water to further improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Wessex Water investigates immediately.
Occasionally low numbers of bacteria were detected in the water leaving of water treatment works and service reservoirs during 1999. The bacteria found were not harmful to consumers' health. The Inspectorate was concerned about the failures at three works and is requiring the Company to take remedial action. The Inspectorate is also requiring the Company to take remedial action at one service reservoir. A small number of samples taken at consumers' taps failed the bacteriological standards. Many of these failures could be due to the condition of the tap, rather than the water itself, but the Inspectorate is requiring the Company to take further action in one water supply zone.
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. Only two out of 797 samples failed to meet the standard during 1999, reflecting the benefits of the additional treatment. In all cases the householder has been 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 parameters provide a good indication of the overall condition of the mains used to distribute drinking water through the region.
The number of zones failing the standard for iron is similar to 1998 and 1997. Wessex Water is carrying out a programme of work to renovate its distribution system. This programme is ongoing, with the Company being required to renovate more than 640 km of mains by the end of 2005.
5. Cryptosporidium
Cryptosporidium is a tiny micro-organism that can sometimes cause a form of diarrhoea called cryptosporidiosis.
Due to new regulations water companies are required by law to sample continuously and analyse daily for cryptosporidium in the treated water at their most vulnerable sites. It is an offence if they fail to meet the new treatment standard.
All water companies had to initially conduct risk assessments at their sites to identify if there was any significant risk of contamination. Wessex Water found that there was significant risk at 19 of its sites. Seven sites have been or are to be taken out of supply and the Company is now continuously sampling and monitoring the treated water at the other 12 sites. In addition to the regulatory requirement, the company is able to get early warning of problems from this monitoring system.
6. Drinking Water Quality Incidents
Wessex Water notified the Inspectorate of four incidents in which drinking water quality deteriorated during 1999.
In June 1999 discoloured water was supplied to consumers in Rockwell following planned overnight work on part of the distribution system. Also in June, discoloured water was supplied to parts of Derry Hill, near Calne, following the unauthorised use of a hydrant. In July, discoloured water was supplied to consumers in Limpley Stoke following supply problems at a service reservoir.
The fourth incident, involving the supply of discoloured water to parts of Market Lavington in August, remains under consideration.
7. Determinations in 1999
Parameter
Total
Contravening PCV No % Coliforms 4835 18 0.4 Faecal coliforms 4841 3 0.1 Colour 1712 0 0.0 Turbidity 4765 4 0.1 Odour 282 0 0.0 Taste 280 0 0.0 Hydrogen ion 4847 1 < 0.1 Nitrate 4526 1 < 0.1 Nitrite 4526 1 < 0.1 Aluminium 1390 1 < 0.1 Iron 1844 13 0.7 Manganese 2318 2 0.1 Lead 797 2 0.3 PAH 1085 53 4.9 Trihalomethanes 365 0 0.0 Total pesticides 681 0 0.0 Atrazine 483 1 0.2 Diuron 223 1 0.4 Isoproturon 256 0 0.0 Simazine 483 1 0.2 Other pesticides 3891 0 0.0 Benzo-3,4-pyrene 1085 1 0.1 All others 56718 0 0.0 Total 102233 103 0.1
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Drinking Water Inspectorate,
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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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