PARTICULATE LEAD IN WATER SUPPLIES (TMU 9024) - Final Report to the Department of the Environment May l987 to December 1991 DoE 2963
Report No DWI0079

Apr 1992


There is a legal requirement that the UK Water Industry will achieve compliance with the Water Supply Regulations (1989)(1). For lead this is a requirement to achieve a concentration of no more than 50ęg/l in all samples analysed for lead. In the case of soluble lead, problem areas have been identified, and successful remedies have been developed. However, insoluble particles of lead corrosion products have been identified in tap water at various locations throughout the UK. These occur despite the application of remedies developed for soluble lead problems.

The objectives of the work described in this report were to confirm the occurrence of particulate lead and to determine the circumstances of its occurrence. Remedial measures were investigated.

Particulate lead problems were evident throughout the UK, generally associated with lead-plumbed premises supplied from soft upland sources.

A size fractionation technique was developed and two types of particulate lead were identified using this technique; flaking lead and particulate/colloidal lead.

Field trials have shown that elevated particulate lead levels are associated with elevated levels of iron and organic matter. Reducing the levels of these parameters results in a decrease in the incidence of particulate lead. The results of the limited field trials to assess the effect on lead of CO2 cleaning lead service pipes show that this technique can eliminate particulate lead under certain circumstances.

Steps should be taken to reduce levels of iron and organic matter in water supplies that experience particulate lead problems in distribution. More comprehensive long-term trials to investigate the effectiveness of CO2 cleaning lead service pipes are recommended.

Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.