Archive:
(for archive/historical purposes, this document has 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 Dee Valley 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.
Dee Valley Water continues to supply you with drinking water of a high quality. In 1999, 99.74% of more than 12,800 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 Dee Valley 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 Dee Valley Water to further improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Dee Valley Water investigates immediately. Occasionally low numbers of bacteria were detected in the water leaving a small number of treatment works and service reservoirs during 1999. The bacteria found were not harmful to consumer's health. Bacteria were detected in 0.4% of water samples from consumers' taps. Many of these could be due to the condition of the tap 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 water pipes being made of lead. Only one of the 81 samples taken by Dee Valley Water failed to met the standard for lead. The householders have been informed of things they can do to reduce lead levels at their tap. 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.
Three samples failed to meet the standards for iron and six samples failed the standard for manganese during 1999. The failures for iron were in an area covered the programme of work being carried out by Dee Valley Water to renovate its distribution system. The programme is ongoing, with Dee Valley Water being required to renovate more than 115 km of mains by 2004. The area affected by the failures for manganese will also be included in this programme
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 now 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 identify if there was any significant risk of contamination. Dee Valley Water identified that there was significant risk at three of its sites and it is now continuously sampling and monitoring the treated water at these sites. At all these sites, the Company is required to ensure adequate treatment is in place and 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
One incident was reported to the Inspectorate, which involved the supply of discoloured water to properties in Marford, Gresford and Borras. The Company was not able to determine with any certainty the cause of the incident.
7. Determinations in 1999
Parameter
Total
Contravening PCV No % Coliforms 800 3 0.4 Faecal coliforms 800 0 0.0 Colour 115 0 0.0 Turbidity 115 0 0.0 Odour 115 0 0.0 Taste 115 0 0.0 Hydrogen ion 557 0 0.0 Nitrate 116 0 0.0 Nitrite 179 9 5.0 Aluminium 154 1 0.7 Iron 147 3 2.0 Manganese 155 6 3.9 Lead 81 1 1.2 PAH 72 0 0.0 Trihalomethanes 72 0 0.0 Total pesticides 72 0 0.0 Other pesticides 1370 0 0.0 All others 1787 0 0.0 Total 6822 23 0.3
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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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