Archive:
(for archive/historical purposes, these documents have not been updated)Index of Contents:
- Introduction
- Bacteria
- Lead
- Iron and Manganese
- Cryptosporidium
- Drinking Water Quality Incidents
- Determinations in 1999
1. Introduction
The Drinking Water Inspectorate (DWI) checks that water companies supply water that is safe to drink when it reaches your home. This document summarises the results of our checks on South West Water Services Limited during 1999 and should be read in conjunction with DWI's "How Good is the Drinking Water?" leaflet which is available here and also from us free of charge from the address at the end of this document.
South West Water continues to supply you with drinking water of a high quality. In 1999, 99.78% of more than 120,400 tests met the standards. This is below the overall figure for England and Wales of 99.82%.
None of the failures in 1999 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 1999 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 further 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 treatment works and service reservoirs during 1999. The Inspectorate was concerned about the failures at one treatment works and one service reservoir. Enforcement action was considered and the Company has taken remedial action at both these installations. Bacteria were detected in 0.5% of samples taken from the consumers taps. Many of these detections could be due to the condition of the tap and not the water itself. The bacteria found were not harmful to consumers' health.
3. Lead
Samples occasionally fail the standard for lead, even where additional treatment has been installed to reduce the amount of lead picked up by water from pipework. In most cases this is due to the consumer's water pipes being made of lead. In all cases the householder has been informed of things they can do to reduce lead levels at their tap. As a result of enforcement action being taken by the Inspectorate the Company is investigating ways of enhancing treatment at one treatment works to reduce the possibility of failure of the lead standard. 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 here and from us free of charge from the address at the end of this document.
4. Iron and Manganese
These two parameters provide a good indication of the overall condition of the mains used to distribute drinking water through the region.
Approximately 3% of the samples taken during 1999 failed the standard for iron and 0.5% for manganese. This was a marked improvement since 1998 when 4.7% of samples failed the iron standard and 0.7% the manganese standard. This shows that programme of work being carried out by South West Water to renovate its distribution system and improve water quality is having an effect. The programme of improvement is ongoing, with South West Water being required to renovate more than 5,565 kilometres of mains by 2010.
5. Cryptosporidium
Cryptosporidium is a tiny micro-organism that can sometimes cause a form of diarrhoea called cryptosporidiosis. There are a number of sources of Cryptosporidium other than water but due to new regulations water companies are now required by law to sample continuously and analyse daily for Cryptosporidium in the treated water at those sites which have a potential vulnerability. All water companies had to initially conduct risk assessments at their sites to identify if there was any significant risk of contamination. South West identified that there was significant risk at 19 of its sites and will be continuously sampling and monitoring the treated water at 13 of these sites by September 2000. A further three will have additional treatment installed by 31 December 2000 and another three will be taken out of service by 31 December 2000. At all these sites, the Company is required to ensure adequate treatment is in place and it is an offence if the new treatment standard for Cryptosporidium is exceeded. In addition to the regulatory requirement, the Company is able to get early warning of any treatment problems from this monitoring system.
6. Drinking Water Quality Incidents
Four incidents in which drinking water quality demonstrably deteriorated were reported to the Inspectorate in 1999.
In July 1999 discoloured water was supplied to consumers in Tretheague Mill following damage to a water main by a third party. In September the Company issued advice not to drink the water to two properties in Hookway, near Crediton following the detection of a coal tar taste. In November the Company issued advice to boil water to 17 properties at Sutcombe after small numbers of indicator bacteria were detected and discoloured water had been supplied following damage to a water main by a third party. In December 1999 structural failure at a service reservoir at Lanner Hill meant that significant revalving was required to maintain supplies which caused some discolouration of water supplies.
No other events regarded as constituting incidents came to the attention of the Inspectorate in 1999.
7. Determinations in 1999
Parameter
Total
Contravening PCV No % Coliforms 4698 24 0.5 Faecal coliforms 4698 3 < 0.1 Colour 2754 0 0.0 Turbidity 2753 8 0.3 Odour 957 0 0.0 Taste 944 0 0.0 Hydrogen ion 2752 6 0.2 Nitrate 1230 0 0.0 Nitrite 1230 0 0.0 Aluminium 2758 1 0.2 Iron 2862 86 3 Manganese 2758 14 0.5 Lead 504 6 1.2 PAH 647 75 11.6 Trihalomethanes 337 0 0.0 Total pesticides 395 0 0.0 2,4-D 336 0 0.0 Other pesticides 14043 0 0.0 All others 19469 0 0.0 Total 66125 223 0.3
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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
Published 12 July 2000 / Updated 11 July 2001
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