§ Mr. MaxtonTo ask the Secretary of State for Scotland what was the level of nitrates recorded in Scottish drinking water in each of the last 20 years.
§ Lord James Douglas-HamiltonInformation is not available in the form requested. Nitrate levels in drinking water differ from one supply to another and may vary seasonally. Surveys carried out in 1975 and 1985 showed that only a very small percentage of the total number of Scottish supply sources contained more than 25 mg of nitrate per litre. Eight of the 12 Scottish water authorities reported that no sources exceeded that figure. All water put into supply was within the EC limit of 50 mg per litre. In 1990 a few small rural supplies were recorded as occasionally exceeding this limit. In these cases nitrate levels are being reduced by blending with other water until the sources can be replaced. Information on nitrate levels in individual supply zones is included in the public records of water quality which water authorities have been required to maintain since 1 July 1990.