Archive:
(for archive/historical purposes, this document has not been updated)Index of Contents:
- Introduction
- Bacteria
- Pesticides
- Lead
- Iron and Manganese
- Cryptosporidium
- Drinking Water Quality Incidents
- Determinations in 1998
1. Introduction
The Drinking Water Inspectorate (DWI) checks that water companies supply water that is safe to drink when it reaches your home. This leaflet summarises the results of our checks on Dee Valley Water plc during 1998. and should be read in conjunction with DWI's "How Good is the Drinking Water ?" leaflet which is available from us free of charge.
Dee Valley Water continues to supply you with drinking water of a high quality. In 1998, 99.88% of more than 12,700 tests met the standards. This is above the overall figure for England and Wales of 99.78%.
None of the failures in 1998 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 1998 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 improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Dee Valley Water investigates immediately. Low numbers of bacteria were found in water leaving one treatment works on two occasions but the Company has taken action to prevent recurrence of the failures. All service reservoirs met the total coliforms standard and only two service reservoirs had trivial breaches of the faecal coliforms standards in 1998. On two occasions very low numbers of bacteria were detected in the water at consumers’ taps during 1998. The bacteria found were not harmful to consumers’ health. It is possible that these failures may have been due to the condition of the tap and not the water itself.
3. Pesticides
Dee Valley Water carried out more than 1,300 tests for individual pesticides during 1998 and all met the stringent standard.
4. Lead
All the tests carried out by Dee Valley Water met the standard for lead. 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 from us free of charge.
5. Iron and Manganese and polycyclic aromatic hydrocarbons (PAH)
These three parameters provide a good indication of the overall condition of the mains used to distribute drinking water through the region.
No samples failed the standards for iron or PAH and only one samples failed the standard for manganese during 1998. This one failure was in an area covered by the programme of work being carried out by Dee Valley Water to renovate its distribution system. The programme of improvement is ongoing, with Dee Valley Water being required to renovate more than 115 km of mains by 2004.
6. Cryptosporidium
Cryptosporidium is a tiny micro-organism which can sometimes cause a form of diarrhoea called cryptosporidiosis. No instances were reported to the Inspectorate of the detection of Cryptosporidium in water leaving Dee Valley Water’s water treatment works during 1998.
Water companies will shortly be required to sample continuously and analyse daily for Cryptosporidium in the treated water at their thertheir most vulnerable sites. It will be an offence if they fail to meet a new treatment standard.
7. Drinking Water Quality Incidents
One incident was reported to the Inspectorate, in November 1998 and it involved the supply of water with a petrol taste to 19 properties in Gwersyllt. The Company advised consumers not to use the water and provided an alternative supply. It was probably caused by disturbance of deposits within the main.
8. Determinations in 1998
Parameter
Total
Contravening PCV No % Coliforms 804 2 0.2 Faecal coliforms 804 0 0.0 Colour 114 0 0.0 Turbidity 114 0 0.0 Odour 114 0 0.0 Taste 114 0 0.0 Hydrogen ion 561 0 0.0 Nitrate 114 0 0.0 Nitrite 131 1 0.8 Aluminium 114 0 0.0 Iron 134 0 0.0 Manganese 153 1 0.7 Lead 82 0 0.0 PAH 72 0 0.0 Trihalomethanes 72 0 0.0 Total pesticides 72 0 0.0 Other pesticides 1368 0 0.0 All others 1796 0 0.0 TOTAL
6733
4
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
Updated 11 July 2001
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