Mains water leakage: Implications for phosphorus source apportionment and policy responses in catchments

Gooddy, Daren Clive and Ascott, Matthew J. and Lapworth, Dan J. and Ward, Robert S. and Jarvie, Helen P. and Bowes, Mike J. and Tipping, Edward William and Dils, Rachael and Surridge, Benjamin William James (2017) Mains water leakage: Implications for phosphorus source apportionment and policy responses in catchments. Science of the Total Environment, 579. pp. 702-708. ISSN 0048-9697

Abstract

Effective strategies to reduce phosphorus (P)-enrichment of aquatic ecosystems require accurate quantification of the absolute and relative importance of individual sources of P. In this paper, we quantify the potential significance of a source of P that has been neglected to date. Phosphate dosing of raw water supplies to reduce lead and copper concentrations in drinking water is a common practice globally. However, mains water leakage (MWL) potentially leads to a direct input of P into the environment, bypassing wastewater treatment. We develop a new approach to estimate the spatial distribution and time-variant flux of MWL-P, demonstrating this approach for a 30-year period within the exemplar of the River Thames catchment in the UK. Our analyses suggest that MWL-P could be equivalent to up to c.24% of the P load entering the River Thames from sewage treatment works and up to c.16% of the riverine P load derived from agricultural non-point sources. We consider a range of policy responses that could reduce MWL-P loads to the environment, including incorporating the environmental damage costs associated with P in setting targets for MWL reduction, alongside inclusion of MWL-P within catchment-wide P permits.