Leading in Lead

Lead is a cumulative poison that affects the nervous system and can slow child development. Lead pipes were used up to the 1980s both for connecting a property to the water supply main and for internal plumbing, due to lead's strength, malleable nature and resistance to corrosion. In the UK, about 40% of properties are supplied via a lead pipe. Lead pipes are, by far, the commonest source of lead in drinking water and CIWEM believes the long term aim must be to replace all lead pipes in the UK. 

The European standard for lead in drinking water (25 µg/l) has applied since December 2003 and is generally measured at the consumer's kitchen tap. This standard will tighten to 10 µg/l in December 2013, although the UK Government has already required some corrective measures to be taken in an attempt to achieve the tighter standard much sooner, as far as it is practicable to do so.

Replacing all lead pipes presents its own challenges. The water distribution network does not release any lead as the materials used for water mains are iron, plastic or asbestos cement. Short-term releases are possible from some pipe-work fittings (particularly brass) and from the corrosion of lead-containing solders used to join copper pipes. As these pipes belong to the property owner there is a deep reluctance to replace their pipes due to the inherent cost, disruption and inconvenience.

An alternative treatment has been promoted in the UK as a first stage of achieving the new European standard. This involves reducing how readily water supplies dissolve the lead in pipes by dosing the water with a corrosion inhibitor; 95% of water supplies in the UK are treated in this way. Other European countries consider dosing as unacceptable on environmental grounds as it could possibly lead to the prolific growth of algae in water bodies. CIWEM considers that this risk is not critical and the environmental aspects of dosing phosphate to water need to be properly balanced with the public health risk of lead in drinking water in the medium term.