§ Mr. Andrew SmithTo ask the Secretary of State for the Environment how many cryptosporidia there have been in an average pint of water supplied by the Thames water authority to the Oxford area in each week since the present water contamination was first detected.
§ Mr. HowardCurrent analytical techniques for monitoring cryptosporidia in water are capable of indicating whether organisms are present in a sample but are not able to provide accurate quantitative results. Techniques for quantification and determination of viability are being developed.
The following results of monitoring have been provided by the Thames water authority. In the three weeks 19 February to 11 March 1989 cryptosporidia were identified in 11 of 38 samples taken at the outlet of treatment works supplying the Oxford area, and in 46 out of 139 samples taken from the distribution system. In the two weeks 12 to 25 March 1989 cryptosporidia were not detected in any of the 25 samples at the treatment works but were detected in six out of 90 samples taken from the distribution system.