Accounting for Polycyclic Aromatic Hydrocarbons in Public Water Supplies

Asset management plans were prepared in 1989 and 1994 by water companies in England and Wales for submission to the Office of Water Services. These plans constituted the financial programming required by water companies to meet specified standards of service, particularly with respect to water quality. Detailed studies have previously established that problems associated with iron from unlined ferrous mains, particularly in soft water areas, is often the main cost ‘driver’for water distribution investment. However, many of the so-called unlined iron mains were treated with a coal-tar pitch lining for corrosion protection before installation, and residues of this painted lining can give rise to unsatisfactory levels of polycyclic aromatic hydrocarbons in drinking water. The paper describes how desk-study research, followed by the development and application of a modified ‘focused downstream series sampling’water-quality modelling technique allowed polycyclic aromatic hydrocarbons to be accounted for in two water company asset management plan submissions. The paper also raises a number of fundamental implications with respect to the occurrence of these carcinogenic compounds in drinking water.