§ Mr. Gordon Prentice
To ask the Secretary of State for the Environment what is the principal cause of the pollution of aquifers in the United Kingdom; and how many have been sterilised since 1990. 
§ Mr. Clappison
A recent Environment Agency study suggested that landfills are the most numerous point sources of pollutants affecting aquifers and that chlorinated solvents from a variety of sources may cause the most serious contamination. No aquifers have been wholly taken out of service or sterilised since 11990. Remedial action has been taken in some cases.