Archive:
(for archive/historical purposes, this document has 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 Anglian 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.
Anglian Water continues to supply you with drinking water of a high quality. In 1999, 99.66% of more than 214,500 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 Anglian 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 Anglian Water to further improve its performance.
2. Bacteria
Whenever bacteria are detected in water samples Anglian Water investigates immediately.
Occasionally low numbers of bacteria were detected in the water leaving a small number of water treatment works during 1999. The bacteria found were not harmful to consumers' health. The Inspectorate was concerned about the failures at one works but the Company took action to prevent a recurrence. Only 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. About 0.4% of samples taken at consumers' taps failed to meet the standard. Many of these failures maybe due to the condition of the tap and not the water itself.
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 many cases this is due to the consumer's water pipes being made of lead. Anglian Water had no samples in 1999 failing the standard for lead.
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.
The number of samples failing the standard for iron has fallen consistently since 1995. This overall improvement reflects the impact of the programme of work being carried out by Anglian Water services Limited to renovate its distribution system. The number of samples failing the standard for manganese has remained about the same over the same period. The programme of improvement is ongoing, with Anglian Water being required to renovate some 893 km of mains by 2002.
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. Anglian Water identified that there was significant risk at five of its sites and is now continuously sampling and monitoring the treated water. 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 problems from this monitoring system.
6. Drinking Water Quality Incidents
The Company reported sixteen incidents in which drinking water quality demonstrably deteriorated.
In January precautionary advice to boil water was issued to about 450 properties in Harlington after small numbers of coliform bacteria were detected following a burst main and supplies in North Elmham and Brisley were affected by discolouration following another burst main. In February discoloured water was supplied to parts of Thetford and Billinghay following planned work on the distribution system, also to Long Stratton following a mains burst. In April parts of Hethersett received discoloured water following planned work on the distribution system and a small number of people in Silsoe experienced a taste problem following an increase in polycyclic aromatic hydrocarbons after a zone boundary valve was relocated. In May supplies to Kirton were discoloured following a burst main and discoloured water was supplied following a minor treatment problem in Biggleswade. In August coliform bacteria were detected in the distribution system to Kirkstead Bridge following biofilm disturbance and low levels were also detected in Sandy service reservoir. In September planned work led to discolouration of supplies to a small part of Colchester and an area of Felixstowe and a burst main caused discolouration of water supplies to a small area in Skegness. In October coliform bacteria were detected after a squirrel gained access to Lakenham service reservoir but there was no evidence that the quality of water in distribution was affected. Also in October the taste of the water to a small area of Swinderby was affected by work on the distribution system. In each of the above incidents the problem was of short duration and the Company took effective remedial action.
7. Determinations in 1999
Parameter
Total
Contravening PCV No % Coliforms 13817 50 0.4 Faecal coliforms 13817 4 0.0 Colour 2287 0 0.0 Turbidity 8941 9 0.1 Odour 947 0 0.0 Taste 954 0 0.0 Hydrogen ion 8825 0 0.0 Nitrate 3908 5 0.1 Nitrite 5639 544 9.6 Aluminium 2426 0 0.0 Iron 5856 42 0.7 Manganese 3789 2 0.1 Lead 1187 0 0.0 PAH 550 31 5.6 Trihalomethanes 485 0 0.0 Total pesticides 2061 0 0.0 Atrazine 1954 0 0.0 Bentazone 1403 0 0.0 Other pesticides 21384 0 0.0 Ammonium 3366 1 < 0.1 Faecal streptococci 4 0 0.0 Nickel 237 0 0.0 Potassium 1316 1 0.1 Sulphate 291 0 0.0 Temperature 13623 1 0.0 Total Hardness 224 3 1.3 All others 25196 0 0.0 Total 144487 693 0.5
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Drinking Water Inspectorate,
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Published 12 July 2000 / Updated 11 July 2001
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