§ Mr. Alex CarlileTo ask the Secretary of State for the Environment what was the incidence of E. coli in drinking water supplies in England and Wales during the latest three years for which information is available; what research has been carried out to isolate the E. coli strain98W which caused the recent deaths in Scotland; what assessment he has made of whether the E. coli strain in Scotland is the same as that found in water supplies; and if he will make a statement. [14592]
§ Mr. ClappisonThere are various strains or serogroups of Escherichia coli—E. coli—bacteria, most of which are unlikely to cause infection in humans. A variety of E. coli strains are present in the faeces of almost all human beings and warm-blooded animals but the incidence of the strain associated with the recent deaths in Scotland—known as 0157—is rare although it has been isolated from cattle in the UK. E. coli in general are used as indicator organisms in checking that drinking water is free from contamination.
Water quality regulations require water companies to test for a group of bacteria known as faecal coliforms which include E. coli. The majority of faecal coliforms reported by water companies will be E. coli but there is no requirement to test specifically for this organism. Whenever faecal coliform bacteria are detected in water supplies, precautionary action is taken, usually through the issue of an advice to boil water notice. The figures for the number of times that faecal coliform bacteria have been found in compliance samples taken in water supply zones in England and Wales is as follows:
1993 1994 1995 Number of tests 164,241 159,869 156,306 Percentage in which faecal coliforms detected 0.1 <0.1 <0.1 The drinking water inspectorate has promoted research to ensure that an effective method of detecting E. coli 0157 in water is available.
All public drinking water supplies in England and Wales are disinfected at the water treatment works and all strains of E. coli are destroyed by adequate disinfection. The drinking water inspectorate checks on a sample basis that adequate disinfection is in place and investigates any disinfection failures.