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 Wessex 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.
Wessex Water continues to supply you with drinking water of a high quality. The number of results meeting the standards has continued to rise and in 1998, 99.91% of more than 164,400 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 Wessex 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 Wessex Water to improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Wessex 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 two works. One of these works has now been abandoned and the Company is carrying out additional monitoring at the other. Two service reservoirs failed to meet the required standard for total coliforms; one has been replaced by a new service reservoir and the Company has taken remedial action at the other. The number of bacteriological failures at consumers' taps has fallen slightly to under 0.5% of the samples taken. Many of these failures maybe due to the condition of the tap and not the water itself.
3. Pesticides
Wessex Water carried out more than 5,000 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
Wessex 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 standard for iron is unchanged from 1997 but no samples failed the standard for manganese during 1998. The number of samples failing to meet the standard for PAH has fallen again for the third consecutive year. This overall improvement reflects the impact of the programme of work being carried out by Wessex Water to renovate its distribution system. The programme of improvement is ongoing, with Wessex Water being required to renovate more than 642 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 Wessex 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 their most vulnerable sites. It will be an offence if they fail to meet a new treatment standard.
7. Drinking Water Quality Incidents
Wessex Water notified the Inspectorate of three incidents during 1998.
In April 1998 discoloured water was supplied to a large area of Devizes, when mains sediments were significantly disturbed following planned work on part of the distribution system. Wessex Water admitted to an offence of supplying water unfit for human consumption and received a formal caution. The Company subsequently modified some of its procedures to reduce the risk of a similar incident.
In June 1998 parts of Bath also received discoloured water because of the unexpected failure of an automatic valve. The Inspectorate made one recommendation following the incident and Wessex Water has taken appropriate action.
In October 1998 a contractor working for Wessex Water inadvertently operated a wrong valve at Dodington water treatment works. This resulted in a small amount of undisinfected water going into a service reservoir. There was no deterioration in the quality of the water supplied to consumers. The Inspectorate made one recommendation following the incident and Wessex Water has taken appropriate action.
8. Determinations in 1998
Parameter
Total
Contravening PCV No % Coliforms 5161 20 0.4 Faecal coliforms 5160 5 0.1 Colour 1806 0 0.0 Turbidity 5173 4 0.1 Odour 295 0 0.0 Taste 298 0 0.0 Hydrogen ion 5174 0 0.0 Nitrate 4779 3 0.1 Nitrite 4779 0 0.0 Aluminium 1457 0 0.0 Iron 1946 14 0.7 Manganese 2464 0 0.0 Lead 786 5 0.6 PAH 1120 55 4.9 Trihalomethanes 379 0 0.0 Total pesticides 699 0 0.0 Atrazine 468 0 0.0 Isoproturon 267 0 0.0 MCPA 265 0 0.0 Mecoprop 265 0 0.0 Simazine 468 0 0.0 Other pesticides 3374 0 0.0 Tetrachloromethane 379 1 0.3 All others 61008 1 0.3 Total 107970 107 0.1
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Updated 11 July 2001
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