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In 1995 there was a large outbreak of cryptosporidiosis in the Torbay area of Devon where drinking water was strongly implicated. The case of supplying water unfit for human consumption brought against the water company was rejected by the Court on the grounds that epidemiological evidence was not admissible. The government therefore decided that new gegulations should be made to ensure that drinking water was treated to adequately remove Cryptosporidium oocysts. These regulations came into force in June 1999. They set a treatment standard of an average of less than one oocyst in 10 litres of water supplied from a treatment works and specify continuous sampling of at least 40 litres per hour of treated water going into supply on each day. Water companies in England and Wales were required to carry out a risk assessment for each of their water treatment works. The assessment considered the source water, the catchment and the treatment provided and established whether there was a significant risk of contravening the standard. The significant risk classification does not imply a contravention of the standard but rather that there is potential for a significant number of Cryptosporidium oocysts to be present at times in the treated water. For works identified as at significant risk, water companies must treat the water to ensure that the standard is met. They must also demonstrate compliance by continuously monitoring the water leaving the works and reporting the results of the daily analysis. As an alternative to continuous monitoring, a water utility may install treatment plants capable of continuously removing or retaining particles greater than one-micron diameter. As currently drafted, the regulations require physical removal of oocysts and do not take into account whether or not oocysts are infectious.

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Edition: Vol. - No. Published: 09/22/2002 Number of Pages: 3File Size: 1 file , 130 KB