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 Mid Southern 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.
Mid Southern 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, 99.87% of more than 50,500 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 Mid Southern 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 Mid Southern Water to improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Mid Southern 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. One service reservoir failed to meet the required standard for total coliforms and the Company has taken remedial action to prevent recurrence of the failure. One sample failed the bacteriological standards at consumers' taps, less than 0.1% of the samples taken. This failure may have been due to the condition of the tap and not the water itself.
3. Pesticides
Mid Southern Water carried out more than 20,700 tests for individual pesticides during 1998 and all but 20 met the stringent standard. The Company is installing treatment at its Beenhams Heath water treatment works to remove pesticides from drinking water. The work is due for completion in February 2001.
4. Lead
No samples failed the standard for lead in 1998, although Mid Southern Water has in the past had samples failing the standard for lead due to the presence of lead pipes in some consumers' properties. 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.
Only one sample failed the standard for iron and no samples failed the standard for manganese during 1998. The number of samples failing to meet the standard for PAH has increased in 1998, but not significantly. Mid Southern Water is taking action to renovate its distribution system. The programme of improvement is ongoing, with the Company being required to renovate more than 270 km of mains by 2005.
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 Mid Southern Water's water treatment works during 1998.
Water companies will shortly be required to continuously sample and analyse daily for Cryptosporidium in the treated water at their most vulnerable sites. It will be an offence if they fail to meet a new treatment standard.
7. Drinking Water Quality Incidents
In March 1998 discoloured water was supplied to approximately 2,900 consumers in the Hindhead area, when mains sediments were significantly disturbed following planned work on part of the distribution system.
In May 1998 the Company supplied water which had not been disinfected from its Maidenhead water treatment works. The ground water treated at this works is of a very high quality and there was no risk to the health of consumers or deterioration in water quality as a result of the incident.
Both incidents remain under investigation.
8. Determinations in 1998
Parameter
Total
Contravening PCV No % Coliforms 2224 1 < 0.1 Faecal coliforms 2224 0 0.0 Colour 325 0 0.0 Turbidity 332 0 0.0 Odour 322 0 0.0 Taste 322 0 0.0 Hydrogen ion 1410 0 0.0 Nitrate 324 0 0.0 Nitrite 356 1 0.3 Aluminium 330 0 0.0 Iron 396 1 0.3 Manganese 359 1 0.3 Lead 206 0 0.0 PAH 325 32 9.8 Trihalomethanes 184 0 0.0 Total pesticides 608 0 0.0 Atrazine 490 0 0.0 Carbetamide 608 0 0.0 Diuron 608 20 3.3 Other pesticides 19026 0 0 Benzo 3,4 pyrene 325 1 0.3 Copper 197 0 0.0 Zinc 198 0 0.0 All others 4114 0 0.0 Total
35813
57
0.2
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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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