Archive:
(for archive/historical purposes, this document has not been updated)Index of Contents:
- Introduction
- Bacteria
- Nitrates
- 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 Bristol 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.
Bristol Water continues to supply you with drinking water of a high quality. The number of results not meeting the standards has fallen consistently since 1991 and during 1998, 99.92% of more than 53,400 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 this year no enforcement action has been necessary.
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 Bristol Water to improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Bristol Water investigates immediately.
Occasionally low numbers of bacteria were detected in the water leaving a small number of water treatment works during 1998. The bacteria found were not harmful to consumers’ health. There has been a significant decrease over the last three years in the number of service reservoirs, and samples from service reservoirs, in which coliforms were detected. The number of bacteriological failures at consumers’ taps remains similar to recent years at 0.3% of the samples taken. Many of these failures may be due to the condition of the tap and not the water itself.
3. Nitrates
Bristol Water had five samples failing the standard for nitrate during 1998 (0.7% of samples taken). This results from a brief high nitrate peak of raw water abstracted from the Gloucester to Sharpness Canal; Bristol Water have installed additional quality monitors and made provision for additional treatment plant if needed.
4. Pesticides
Bristol Water carried out more than 4,400 tests for individual pesticides during 1998 and all met the stringent standard. This reflects the significant investment in recent years to install treatment to remove pesticides from drinking water.
5. Lead
Bristol Water had no samples failing the standard for lead during 1998, mainly as a result of additional treatment installed to reduce the amount of lead picked up by water from pipework. 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.
6. 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.
The number of samples failing the standard for iron is reduced from 1997 but no samples failed the standard for manganese during 1998. The number of samples failing to meet the standard for PAH has fallen again for the third consecutive year. This overall improvement reflects the impact of the programme of work being carried out by Bristol Water to renovate its distribution system. The programme of improvement is ongoing, with Bristol Water being required to renovate more than 253 km of mains by 2002.
7. 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 Bristol 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 their most vulnerable sites. It will be an offence if they fail to meet a new treatment standard.
8. Drinking Water Quality Incidents
No incidents were reported by the Company to the Inspectorate in 1998.
9. Determinations in 1998
Parameter
Total
Contravening PCV No % Coliforms 2895 10 0.3 Faecal coliforms 2895 0 0.0 Colour 395 0 0.0 Turbidity 402 0 0.0 Odour 395 0 0.0 Taste 393 0 0.0 Hydrogen ion 393 0 0.0 Nitrate 540 5 0.9 Nitrite 540 0 0.0 Aluminium 396 0 0.0 Iron 613 6 1.0 Manganese 395 0 0.0 Lead 216 0 0.0 PAH 266 7 2.6 Trihalomethanes 217 0 0.0 Total pesticides 868 0 0.0 Other pesticides 4460 0 0.0 Ammonium 431 0 0.0 Antimony 115 0 0.0 All others 11123 0 0.0 Total 27948 28 < 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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