The presence of lead in drinking water poses a range of risks to human health, including the retardation of some aspects of child development, the inducement of abortion, and other clinical disorders. The extent of these risks has not been quantified at the European Union (EU) scale.A number of sampling methods are in use across the EU, some of which are inadequate for determining the concentrations of lead in drinking water at consumers' taps. In consequence, non-compliance with the EU standards for lead in drinking water has been under-estimated.Emerging data indicates significant non-compliance with these standards in some countries, particularly with the 10 mg l 21 standard that will become a legal requirement in 2013; the current interim standard of 25 mg l 21 is also exceeded in some locations. An initial estimate is that 25% of domestic dwellings in the EU have a lead pipe, either as a connection to the water main, or as part of the internal plumbing, or both, potentially putting 120 million people at risk from lead in drinking water within the EU. These issues are relevant to the implementation of the Protocol on Water and Health and to drinking water safety planning.

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Dwr Cymru Welsh Water supplies over three million people with drinking water throughout most of Wales (UK). Ortho-phosphate has increasingly been dosed at around 1 mg/L (P) to further reduce the corrosivity of supplies to the lead pipes which connect approximately 30% of houses to water mains in the company's area, additional to long-establish pH adjustment measures. The installation of new ortho-phosphate dosing schemes and the optimisation of these and existing dosing schemes, 29 schemes in total, were subject to a regulatory programme of work, agreed with the Drinking Water Inspectorate (DWI). Optimisation comprised (i) selection of appropriate ortho-phosphate doses by a procedure involving laboratory based plumbosolvency testing linked to zonal lead emission (compliance) modelling, (ii) tight dose control and (iii) extensive monitoring of lead in supply by random daytime (RDT) sampling and by the use of lead pipe test rigs. The successful outcome was confirmed by 99% of over 5,000 RDT samples complying with the future standard of 10 microg/L for lead in drinking water.

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