Archive:
(for archive/historical purposes, these documents have not been updated)Index of Contents:
- Introduction
- Bacteria
- Pesticides
- 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 Southern 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.
Southern Water continues to supply you with drinking water of a high quality. In 1999, 99.81% of more than 80,900 tests met the standards. This is very close to 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 Southern 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 Southern Water to further improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Southern Water investigates immediately. Occasionally low numbers of bacteria were detected in the water leaving water treatment works and service reservoirs during 1999. The bacteria found were not harmful to consumers' health. Bacteria were detected at consumers' taps in 0.13% of the samples taken. Some of these failures may have been due to the condition of the consumers' tap and not the water itself.
3. Pesticides
1999 was the first year in which all samples taken passed the standard for individual and total pesticides. This reflects the significant investment in recent years to install treatment and operate treatment to remove pesticides from drinking water.
4. Lead
The Drinking Water Inspectorate has accepted an undertaking from Southern Water to install treatment to reduce the amount of lead picked up from pipework in one additional water supply zone. 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 many 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. 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.
5. 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. The number of zones failing the standard for iron and manganese is similar to previous years, with nearly all failures occurring within water supply zones where the Company is already committed to taking remedial action. Only two samples failed the standard for manganese the same number as 1998. Southern Water's programme of mains improvement continues with a target to renovate a further 107 km of mains by 2001.
6. 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 treated water continuously and analyse daily for Cryptosporidium at those sites which have a potential vulnerability. All water companies had to initially conduct risk assessments at their water treatment works and associated raw water sources to identify if there was any significant risk of contamination. Southern Water identified that there was significant risk at 11 of its sites and it is now continuously sampling and monitoring the treated water at 10 of these sites, the other site is not in use. At all these sites, the Company is required to ensure adequate treatment is in place and it is an offence if the new regulatory standard for Cryptosporidium is exceeded. In addition to the regulatory requirement, the company is able to get early warning of problems from this monitoring system.
7. Drinking Water Quality Incidents
During 1999, two incidents in which drinking water quality deteriorated were reported to the Inspectorate. In September, low numbers of Cryptosporidium were detected in service reservoirs supplying consumers in Arun district and in the treated water leaving the St Lawrence Springs treatment works on the Isle of Wight. In both cases the Company took remedial action and no increase in the number of cases of cryptosporidiosis was detected. It was not considered appropriate to issue advice to boil water. Additional monitoring has been initiated at the water sources involved. There were no other water quality incidents.
8. Determinations in 1999
Parameter
Total
Contravening PCV No % Coliforms 6325 8 0.1 Faecal coliforms 6334 0 0.0 Colour 876 0 0.0 Turbidity 876 1 0.1 Odour 423 0 0.0 Taste 423 0 0.0 Hydrogen ion 920 0 0.0 Nitrate 873 0 0.0 Nitrite 873 0 0.0 Aluminium 873 0 0.0 Iron 1316 12 0.9 Manganese 898 2 0.2 Lead 523 6 1.1 PAH 1056 102 9.7 Trihalomethanes 468 0 0.0 Total pesticides 401 0 0.0 Chlorthal 0 0 0.0 MCPA 269 0 0.0 Other pesticides 7556 0 0.0 Benzo-3,4-pyrene 1056 3 0.3 All others 9339 0 0.0 Total 41678 134 0.3
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Drinking Water Inspectorate,
Floor 2/A1, Ashdown House, 123 Victoria Street, London, SW1E 6DE
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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