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 Southern 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.
Southern Water continues to supply you with drinking water of a high quality. The number of results not meeting the standards has fallen consistently since 1991 and duringin 1998, 99.83% of more than 83,100 tests met the standards. This is similar to 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 Southern 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 Southern Water to improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Southern Water investigates immediately.
On single occasions low numbers of bacteria were detected in the water leaving three of the Company’s water treatment works during 1998. The bacteria found were not harmful to consumers’ health and subsequent samples demonstrated that water quality was fully satisfactory. All of the Company’s service reservoirs met the required standard for total coliforms. On one occasion low numbers of bacteria were detected at a single service reservoir. The Company took immediate action to rectify a fault identified on some newly installed sampling pipework. The number of bacteriological failures at consumers’ taps continued to fall to under 0.25% 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
Southern Water carried out nearly 9,000 tests for individual pesticides during 1998 and 4 results failed to meet the stringent standard. This reflects the significant investment in recent years to install treatment to remove pesticides from drinking water.
4. Lead
One of over 500 samples taken during 1998 failed the standard for lead. The continuing decrease in the numbers of samples failing the lead standard reflects the completion in 1995 of additional treatment to reduce the amount of lead picked up by water from pipework. 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 increased from 1997, but nearly all failures occurred within water supply zones where the Company is already committed to taking remedial action. The 2 samples which failed the standard for manganese were from a single supply zone and the Inspectorate required the Company to ensure that this supply zone is added to the programme of mains’ renovation work already identified. The number of samples failing to meet the standard for PAH has fallen compared to 1997. This may reflect the initial impact of the programme of work being carried out by the Company to renovate its distribution system. The programme of improvement is ongoing, with Southern Water being required to renovate more than 207 km of mains by 2001.
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 Southern 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 theirtheir most vulnerable sites. It will be an offence if they fail to meet a new treatment standard.
7. Drinking Water Quality Incidents
In June 1998, total coliform bacteria were detected in a small number of properties in Icklesham following an unauthorised connection of a renewed main by contractors. The Company advised affected consumers to boil water and took prompt operational measures to restore normal water quality.
In December 1998, a chlorination failure occurred at Balsdean water treatment works which resulted in unchlorinated water being pumped into supply. Subsequent sampling indicated that the bacteriological quality of supplies was satisfactory. The Inspectorate concluded that there were a number of deficiencies in operating and monitoring procedures. Following its assessment of the incident the Inspectorate made five5 recommendations to which Southern Water has taken appropriate action.
8. Determinations in 1998
Parameter
Total
Contravening PCV No % Coliforms 6189 14 0.2 Faecal coliforms 6189 1 < 0.1 Colour 861 0 0.0 Turbidity 975 0 0.1 Odour 469 0 0.0 Taste 460 0 0.0 Hydrogen ion 867 0 0.0 Nitrate 859 0 0.0 Nitrite 859 0 0.0 Aluminium 859 0 0.0 Iron 1290 16 1.2 Manganese 1003 2 0.2 Lead 576 1 0.2 PAH 1349 90 6.7 Trihalomethanes 476 0 0.0 Total pesticides 447 0 0.0 2,4-D 299 0 0.0 Atrazine 314 0 0.0 Chlorotoluron 309 0 0.0 Chlorthal 299 4 1.3 Linuron 309 0 0.0 MCPA 299 0 0.0 Mecoprop 299 0 0.0 Other pesticides 6788 0 0.0 Benzo-3,4-pyrene 1349 5 0.4 Phosphorus 125 0 0.0 All others 9356 0 0.0 TOTAL 43474 133 0.3
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Drinking Water Inspectorate,
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Telephone : 020 7944 5956 - Facsimile : 020 7944 5969
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Updated 11 July 2001
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