Water is a precious resource, particularly on an island with a finite supply. Jersey's natural water is vulnerable to the effects of diffuse pollution, such as nitrates and pesticides caused principally by agricultural activity. The levels of agro-chemicals in water resources can often require costly treatment through careful blending, dilution and treatment by Jersey Water before water enters the public supply.

A risk assessment for the year was undertaken for monitoring pesticides in the raw water resources used by Jersey Water. The decision was made to concentrate on ensuring the water taken from the reservoirs and sent for treatment was the best available. Weekly monitoring of all the reservoirs using an analytical method which provides a broad scan for 450 substances was undertaken which enabled the Company to quickly identify if there were any issues. This indicator focuses on the percentage of analyses where pesticides were detected above the European Drinking Water Directive standard of 0.1µg/l (1 part in ten billion) for each individual pesticide in drinking water. This is usually the limit of laboratory detection and is not a health-based limit.