Index of Contents:
- Introduction
- Coliform Bacteria
- Pesticides
- Lead
- Iron and Manganese
- Cryptosporidium
- Drinking Water Quality Incidents
- Determinations in 2000
- Further Information
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 Severn Trent Water Limited during 2000 and should be read in conjunction with DWI's ‘How Good is the Drinking Water?’ leaflet which is available from us free of charge or on the DWI web site.
Severn Trent Water continues to supply you with drinking water of a high quality. In 2000, 99.90% of more than 231,100 tests met the standards. This is above the overall figure for England and Wales of 99.83%.
None of the failures in 2000 were likely to harm consumers’ health. We assessed each one and, where necessary, we have required Severn Trent Water to take action to prevent further failures.
Although the 2000 results are good, we know that there are some matters which may be of everyday concern to consumers. These are detailed below including any steps taken by Severn Trent Water to further improve its performance.
2. Coliform Bacteria
Whenever coliform bacteria are found in water samples, Severn Trent Water investigates immediately. Occasionally, low numbers were detected in the water leaving a small number of water treatment works and service reservoirs during 2000. The bacteria found were not harmful to consumers’ health.
The Inspectorate was concerned about the failures at one water treatment works and initiated enforcement action to require improvements to be made at this works. The Inspectorate regarded all other failures at water treatment works and service reservoirs as trivial.
Coliform bacteria were detected in 0.4% of the samples taken from consumers’ taps. The standard permits 5% of samples in any zone to contain coliform bacteria and all zones met the standard. This is similar to last year’s result. Many of these detections could be due to the condition of the tap and not the water itself.
3. Pesticides
Severn Trent Water carried out more than 6,300 tests for individual pesticides during 2000 and all samples met the stringent standard. This reflects the significant investment in recent years to install treatment to remove pesticides from drinking water.
4. Lead
Samples do 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 any problems and 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 from us free of charge or on the DWI web site. Only three of 624 samples taken by Severn Trent Water failed the standard for lead during 2000.
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 area of supply. Twenty-nine of the 4,748 samples taken failed the standard for iron during 2000. This is an improvement since 1999. In addition, of the 1,636 samples taken, three failed the standard for manganese, which is about the same as that in 1999. Severn Trent Water has recently completed a programme to renovate 3,940 km of water mains between 1995 and 2000. This improvement programme is ongoing, with Severn Trent Water being required to rehabilitate approximately 1,900 km of water mains by 2003.
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. New Regulations require water companies by law to sample continuously and analyse daily for Cryptosporidium in the treated water at those sites that have a potential vulnerability. It is a criminal offence if the new treatment standard for Cryptosporidium is exceeded.
Severn Trent Water has implemented continuous sampling and monitoring at eight of its sites that were identified to be of significant risk in 1999. In addition, as part of the new Regulations, the Company is committed at three sites to improvement programmes. These programmes will be completed by 2002.
It is also a requirement for the Company to notify the Inspectorate of any failures to meet the standard, and Severn Trent Water reported no failures during 2000.
7. Drinking Water Quality Incidents
The Inspectorate regarded 19 of the events notified during 2000 by the Company as incidents in which drinking water quality demonstrably deteriorated. Each of the incidents assessed by DWI was of short duration and the Company took remedial action. Seven recommendations were made to the Company mainly regarding operations and procedures. In addition, in 2000 assessment was completed for one incident which occurred in 1998.
Summary of water quality incidents reported in 2000
Nature of Incident No. of Incidents Assessment by DWI Completed Areas Affected Supply of discoloured water
12 Yes Sutton-in-Ashfield, Wolverhampton (January); Malvern, Ilkeston, Derby (February); Walton (May); South Birmingham (June); Ripley, Hackenthorpe (August); Leamington Spa (September); Broxtowe, Droitwich (December) 3 No Malvern (February); Wolverhampton, Warwick (November) Wholesomeness concerns relating to service reservoirs 1 Yes Church Stretton (November) Wholesomeness concerns relating to water in the distribution system 1 Yes Whitchurch (June) Loss of supply 1 Yes Selston (October) 1 No Roel Hill (June) 8. Determinations in 2000
Water supply zones
In general, to be wholesome, water must comply with the standards set out in the Regulations. The Company carried out a total of 137,487 tests on samples taken in its 286 water supply zones. The table below includes only the parameters that breached the standard. All other parameters fully complied with the standards. Parameter meanings can be found at the beginning of this section.
The last column indicates the number of failures in zones already covered by legally binding undertakings given by the Company to carry out remedial works to overcome the difficulty in meeting the individual standard.
Parameter Total samples taken Samples not meeting the standard Percentage Number of failures already covered by undertakings Total coliforms 20,028 83 0.41 - Faecal coliforms 20,028 5 0.02 - Turbidity 4,038 3 0.07 1 Taste 1,407 1 0.07 - Nitrite 1,568 4 0.26 - Aluminium 1,602 2 0.12 - Iron
4,748 29 0.61 16 Manganese 1,636 3 0.18 - Lead 624 3 0.48 - PAH 956 42 4.39 - Benzo3,4 pyrene 958 5 0.52 - 9. Further Information
If you would like more information about drinking water quality the following leaflets are available free of charge from DWI and can also be found on the DWI web site:
- What do we do?
- How good is the drinking water?
- Problems with your drinking water
- Chlorine, smell and taste
- Discoloured water
- Lead in drinking water
- Private water supplies
- Water hardness
- Tap water, where does it come from and how is it made safe to drink?
- Using lead-free solder for drinking water fittings
- DWI reports on each water company
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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 11 July 2001
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