§ Mr. Tony Lloydasked the Secretary of State for the Environment if he has any information on the effectiveness of raising pH levels of water and the addition of orthophosphates to reduce plumbosolvency.
§ Mr. John PattenYes. Information and advice on this subject is contained in "Lead in Potable Water", technical note No. 5, issued by my Department in May 1984. I am sending the hon. Member a copy.
§ Mr. Tony Lloydasked the Secretary of State for the Environment (1) if he has made an assessment of the need to replace lead piping in water supply systems in order to reduce lead content in water;
(2) if he has made any assessment of the number of dwellings in England and Wales which need replacement of lead piping in order to reduce lead content in water, and of the cost.
§ Mr. John PattenAs the lead concentration in a dwelling's water supply is dependent on a variety of factors, it is not possible to make any exact assessment of the number of dwellings where pipe replacement would be necessary. Surveys carried out by water undertakers over the last decade at the request of the Government indicate that between 100,000 and 300,000 household may have some pipework that needs to be replaced. This would normally be the property's service pipe and pipework to a drinking water tap, which is the owner's responsibility, and the communication pipe between the water main and the service pipe, which is the water undertaker's responsibility.
The average cost per dwelling is estimated at just over £500; on our estimates, the householder would on average bear about two thirds of this cost. Those costs which fall to the water authorities will be met from within their existing resources.