title: Mains water leakage: Implications for phosphorus source apportionment and policy responses in catchments.
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.
authors.affiliation: British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK. Electronic address: dcg@bgs.ac.uk.
authors.forename: Daren C
authors.initials: DC
authors.lastname: Gooddy
authors.affiliation: British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ascott
authors.affiliation: British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK.
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Lapworth
authors.affiliation: British Geological Survey, Keyworth, Nottingham NG12 5GG, UK.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ward
authors.affiliation: Centre for Ecology and Hydrology, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK.
authors.forename: Helen P
authors.initials: HP
authors.lastname: Jarvie
authors.affiliation: Centre for Ecology and Hydrology, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK.
authors.forename: Mike J
authors.initials: MJ
authors.lastname: Bowes
authors.affiliation: Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster LA1 4AP, UK.
authors.forename: Edward
authors.initials: E
authors.lastname: Tipping
authors.affiliation: Environment Agency, Red Kite House, Wallingford, Oxon OX10 8BD, UK.
authors.forename: Rachael
authors.initials: R
authors.lastname: Dils
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
authors.forename: Ben Wj
authors.initials: BW
authors.lastname: Surridge
keywords: Eutrophication; Health; Mains water leakage; Phosphate; Policy