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 South West Water Services 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.
South West Water continues to supply you with drinking water of a high quality. The number of results not meeting the standards has fallen consistently since 1995 and in 1998, 99.75% of more than 114,400 tests met the standards. This is similar to 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 South West 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 South West Water to improve its performance.
2. Bacteria
Whenever bacteria are found in water samples South West 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. The Inspectorate was concerned about the failures at one works. The Company has since taken action at this works. All other failures at works and service reservoirs are not significant. The number of bacteriological failures at consumers’ taps has remained constant at about 0.2% of the samples taken. Many of these failures may be due to the condition of the tap and not the water itself.
3. Pesticides
South West Water carried out more than 14,800 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.
4. Lead
South West Water 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 the standards for these parameters is almost unchanged from 1997. This is despite the programme of work being carried out by South West Water to renovate its distribution system. The programme of improvement is ongoing, with South West Water being required to renovate more than 5,564 km of mains by 2010.
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 South West 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 theirtheir most vulnerable sites. It will be an offence if they fail to meet a new treatment standard.
7. Drinking Water Quality Incidents
In January 1998 discoloured water was supplied to parts of Exeter, when mains sediments were significantly disturbed following a burst main.
In February 1998 bacteria, which were not harmful to health, were found in water supplied from Braunton service reservoir. The problem was traced to contaminated sampling equipment.
In May 1998 there was a failure of the disinfection system at Uton water treatment works. The Company advised 3,750 people to boil their water, as a precaution, while repairs were carried out and the Company carried out tests to show that the water was not contaminated.
8. Determinations in 1998
Parameter
Total
Contravening PCV No % Coliforms 4651 16 0.3 Faecal coliforms 4654 3 0.1 Colour 2163 0 0.0 Turbidity 2163 2 0.1 Odour 908 0 0.0 Taste 904 1 0.1 Hydrogen ion 2160 2 0.1 Nitrate 1158 0 0.0 Nitrite 1162 1 0.1 Aluminium 2166 0 0.0 Iron 2166 102 4.7 Manganese 2166 16 0.7 Lead 482 6 1.2 PAH 745 93 12.5 Trihalomethanes 367 0 0.0 Total pesticides 448 0 0.0 Chloropropham 357 0 0.0 2,4-D 368 0 0.0 MCPA 368 0 0.0 Simazine 357 0 0.0 Other pesticides 13437 0 0.0 All others 16543 0 0.0 Total 59893 242 0.4
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Drinking Water Inspectorate,
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Updated 11 July 2001
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