Estimating the leakage contribution of phosphate dosed drinking water to environmental phosphorus pollution at the national-scale

Abstract

Understanding sources of phosphorus (P) to the environment is critical for the management of freshwater and marine ecosystems. Phosphate is added at water treatment works for a variety of reasons: to reduce pipe corrosion, to lower dissolved lead and copper concentrations at customer's taps and to reduce the formation of iron and manganese precipitates which can lead to deterioration in the aesthetic quality of water. However, the spatial distribution of leakage into the environment of phosphate added to mains water for plumbosolvency control has not been quantified to date. Using water company leakage rates, leak susceptibility and road network mapping, we quantify the total flux of P from leaking water mains in England and Wales at a 1 km grid scale. This is validated against reported leaks for the UKs largest water utility. For 2014, we estimate the total flux of P from leaking mains to the environment to be c. 1.2 kt P/yr. Spatially, P flux is concentrated in urban areas where pipe density is highest, with major cities acting as a significant source of P (e.g. London into the Thames, with potentially 30% of total flux). The model suggests the majority (69%) of the P flux is likely to be to surface water. This is due to leakage susceptibility being a function of soil corrosivity and shrink-swell behaviour which are both controlled by presence of low-permeability clays. The location of major cities such as London close to the coast results in a potentially significant flux of P from mains leakage to estuarine environments. The contribution of leakage of phosphate dosed mains water should be considered in future source apportionment and ecosystem management. The methodology presented is generic and can be applied in other countries where phosphate dosing is undertaken or used prior to dosing during investment planning.

Phosphate uptake behavior and mechanism analysis of facilely synthesized nanocrystalline Zn‐Fe layered double hydroxide with chloride intercalation

“…A variety of industrial and agricultural effluents contains high concentration of phosphorus. It is well known that if phosphate is discharged into water bodies excessively, it may cause the eutrophication of water body and subsequent deterioration of water quality . Thus, it is of vital importance to efficiently remove phosphate from wastewater.…”

Provenance of drinking water revealed through compliance sampling

“…It would be anticipated that phosphate would be similarly useful were its distribution not obscured by treatment for plumbosolvency. 44,[59][60][61] The spatial distribution of nickel and selenium (Fig. 3) reects geochemical processes occurring as recharge occurs through overlying supercial deposits.…”

“…Recent work has shown mains water leakage to be a signicant source of phosphorus (P) to the environment. 60,61,73,74 Transfer of phosphorus dosed mains water into an area without historic P…”

Macronutrient status of UK groundwater: Nitrogen, phosphorus and organic carbon

“…There is as yet little data on the reduction in groundwater P from agricultural measures as these tend to focus on surface water impacts (Oenema et al, 2005). The source of P to the aqueous environment represented by addition of phosphate to drinking water to control plumbosolvency has become increasing recognised (Ascott et al, 2016). Up to 1200 tonnes of P may be lost through mains leakage every year and will become more significant as phosphate stripping in sewage treatment works continues to improve.…”

“…Up to 1200 tonnes of P may be lost through mains leakage every year and will become more significant as phosphate stripping in sewage treatment works continues to improve. P inputs to the environment from leakage are concentrated in urban centres and in many cases these are close to surface water bodies including estuaries (Ascott et al, 2016).…”