Jersey's treated water supply is vulnerable to the effects of diffuse nitrate and pesticide pollution across the Island. Driven principally by agricultural activity, the levels of these agro-chemicals in water resources regularly exceed the regulatory limits for treated water. Jersey Water manages this risk through careful blending, dilution and treatment (where possible). However, on occasion, there are unavoidable occassions where nitrates in treated water may briefly exceed the limit to a minor degree. Jersey Water has a dispensation for nitrates under the Water (Jersey) Law 1972, which allows for a maximum concentration of 65mg/l and places additional restrictions on the number of samples exceeding the 50mg/l limit. The dispensation expires in December 2021. This indicator measures the maximum concentration of nitrates detected in treated water.

For the ninth consecutive year, nitrate concentrations in Jersey's treated water supply were fully compliant with regulatory requirements and the maximum concentration of nitrates detected in treated water was 38.4mg/l; below the regulatory limit of 50mg/l.