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
- Prosecutions
- 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 Dwr Cymru Welsh Water 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.
DwrCymru Welsh Water continues to supply you with drinking water of a high quality. In 1998, 99.71% of more than 194,300 tests met the standards. This is below 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 Dwr Cymru Welsh 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 Dwr Cymru Welsh Water to improve its performance.
2. Bacteria
Whenever bacteria are found in water samples Dwr Cymru Welsh 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 three works and is requiring the Company to carry out improvements. 17 out of 597 service reservoirs failed to meet the required standard. The Inspectorate is concerned about the failures at four of these service reservoirs and is requiring the Company to carry out improvements. There has been a reduction in the number of bacteriological failures at consumers’ taps from previous years. Some of these failures are likely to be due to the condition of the tap and not the water itself. However the Inspectorate was concerned about the number of bacteriological failures in one zone and is requiring the Company to take action.
3. Pesticides
Dwr Cymru Welsh Water carried out more than 36,300 tests for individual pesticides during 1998. Only eight of these tests did not meet the stringent standard.
4. Lead
Of over 1,000 tests carried out by Dwr Cymru Welsh Water, 0.9% did not meet the standard for lead. In 1995 the number of samples failing to meet the lead standard was has fallen from 2.8% in 1995. Failures do occur 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. However, the Inspectorate was concerned about the levels of lead in one zone where treatment has not been installed and is requiring the Company to take action. 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 and PAH has reduced from last year1997. The number of samples failing the manganese standard has remained unchanged for the past three years. This overall improvement reflects the impact of the programme of work being carried out by Dwr Cymru Welsh Water to renovate its distribution system. The programme of improvement is ongoing, with Dwr Cymru Welsh Water being required to renovate more than 4,786 km of mains by 2010.
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 Dwr Cymru Welsh 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 their most vulnerable sites. It will be an offence if they fail to meet a new treatment standard.
7. Drinking Water Quality Incidents
Ten incidents were reported to the Inspectorate during 1998. One involved the supply of discoloured water from Ponsticill works following loss of output in April; two involved the issue of advice to boil water, in June following detection of a low level of coliform bacteria in the water supply after an electrical failure during a storm resulted in Llithfaen high level service reservoir running dry, and in August following detection of coliform bacteria in Penyrheolddu service reservoir; four involved discolouration of the water supply following mains bursts, two to parts of Rhyl in July and September and two in Pembrokeshire in October and December; two involved discolouration following planned distribution work in Erwood in August and Haverfordwest in October; and one involved taste due to an algal bloom at Sluvad treatment works in October. The Company has carried out reviews of various procedures as the result of recommendations made by the Inspectorate.
8. Prosecutions
During 1998, Dwr Cymru Welsh Water pleaded guilty to supplying water unfit for human consumption in two cases brought by the Inspectorate where highly discoloured water was supplied. These incidents affected an area from Tregaron to the coast at Llanon and north to Ysbyty Ystwyth in June 1997 and an area supplied by Crai treatment works in July 1997. The fines in these cases were £17,500 and £24,000 respectively.
9. Determinations in 1998
Parameter
Total
Contravening PCV No % Coliforms 9557 54 0.6 Faecal coliforms 9552 5 0.1 Colour 1315 0 0.0 Turbidity 1497 4 0.3 Odour 1802 4 0.2 Taste 1706 6 0.4 Hydrogen ion 1404 3 0.2 Nitrate 981 0 0.0 Nitrite 2326 146 6.3 Aluminium 1853 5 0.3 Iron 3605 95 2.6 Manganese 2085 20 1.0 Lead 1093 10 0.9 PAH 1340 69 5.1 Trihalomethanes 800 7 0.9 Total pesticides 1634 1 0.1 Asulam 883 1 0.1 Atrazine 877 1 0.1 2,4-D 862 2 0.2 2,4-DB 803 1 0.1 Diuron 837 0 0.0 Glyphosate 758 0 0.0 MCPA 890 1 0.1 MCPB 804 0 0.0 Mecoprop 889 2 0.2 Methabenzthiazuron 895 0 0.0 Mancozeb 834 0 0.0 Simazine 1027 0 0.0 Trietazine 684 0 0.0 Other pesticides 25309 0 0.0 Ammonia 988 0 0.0 Antimony 234 0 0.0 Benzo 3,4 pyrene 1340 1 0.1 Oxidisability 209 0 0.0 Phosphorus 220 0 0.0 Temperature 9206 0 0.0 Tetrachloromethane 403 1 0.2 Zinc 254 0 0.0 All others 10086 0 0.0 Total
101842
439
0.4
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Updated 11 July 2001
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