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
- Prosecutions
- 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 Severn Trent Water Limited 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.
Severn Trent Water continues to supply you with drinking water of a high quality.In 1998, 99.88% of more than 266,700 tests met the standards. This is above the overall figure for England and Wales of 99.78% for all of England and Wales.
None of the failures in 1998 were likely to harm consumers’ health. We assessed each one and, where necessary, have required Severn Trent 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 Severn Trent Water to improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Severn Trent 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. 12 out of 656 service reservoirs failed to meet the required standard and the Company has taken remedial action to prevent recurrence of the failures. The number of bacteriological failures at consumers’ taps has increased slightly to 0.5% of the samples taken. Many of these failures are likely to be due to the condition of the tap and not the water itself.
3. Pesticides
Severn Trent Water carried out 6,000 tests for individual pesticides during 1998 and only two failed to meet the stringent standard. This reflects the significant investment in recent years to install treatment to remove pesticides from drinking water.
4. Lead
Severn Trent continues to have samples occasionally failing the standard for lead, even where additional treatment has been installed to reduce the amount of lead picked up by water from pipework. 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 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.
The number of samples failing for iron decreased in 1998, only five samples failed the manganese standard but there was an increase in failures for PAH. A major programme of work is being carried out by Severn Trent Water to renovate its distribution system. The programme of improvement is ongoing, with the Company being required to renovate more than 1,899 km of mains by 2003.
6. Cryptosporidium
Cryptosporidium is a tiny micro-organism which can sometimes cause a form of diarrhoea called cryptosporidiosis. One instance was reported to the Inspectorate of the detection of a very low number of Cryptosporidium in water leaving a Severn Trent water treatment works during 1998. The Company took the works out of supply and there was no reported increase in cryptosporidiosis in the community.
Water companies will shortly be required to sample continuously and analyse daily for Cryptosporidium in the treated water at theirtheir most vulnerable sites. It will be an offence if they fail to meet a new treatment standard.
7. Drinking Water Quality Incidents
Nine incidents were reported to the Inspectorate during 1998. Two involved the supply of discoloured water following mains bursts in the Styvechale area of Coventry in January and in Malvern in August; three others also involved discolouration of water supplies, two following planned work, at Essington in April and at Hodge Hill in May, and one following a power failure affecting the supply to the Ettington area in April. One concerned possible back-siphonage in Aylestone, Leicester in March; one involved the issue of advice not to drink the water because of taste and odour problems after revalving operations following a mains burst at Childswickham in October; one involved loss of disinfection at Wildmoor treatment works in July; and one involved incorrect connections near Chesterfield in August.
8. Prosecutions
During 1998, Severn Trent Water pleaded guilty to supplying water unfit for human consumption in a case brought by the Inspectorate where highly discoloured water was supplied to the villages of Gnosall, Ranton and Haughton in Staffordshire in July 1997. The Company was fined £8,000.
9. Determinations in 1998
Parameter
Total
Contravening PCV No % Coliforms 20904 97 0.5 Faecal coliforms 20908 5 < 0.1 Colour 1447 0 0.0 Turbidity 1456 0 0.0 Odour 3346 2 0.1 Taste 1213 0 0.0 Hydrogen ion 1788 1 0.1 Nitrate 5270 0 0.0 Nitrite 1525 8 0.5 Aluminium 1682 2 0.1 Iron 4311 40 0.9 Manganese 2038 5 0.2 Lead 2394 20 0.8 PAH 1311 44 3.4 Trihalomethanes 895 5 0.6 Total pesticides 2088 0 0.0 Atrazine 1120 1 0.1 Chlorotoluron 64 0 0.0 Clopyralid 262 0 0.0 Isoproturon 527 0 0.0 MCPA 517 0 0.0 Mecoprop 576 1 0.2 Other pesticides 2927 0 0.0 Benzo-3,4-pyrene 1320 6 0.5 Nickel 2243 0 0.0 Surfactants 683 0 0.0 Tetrachloroethene 719 0 0.0 All others 75427 0 0.0 Total 158961 237 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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