In November 2012, routine sampling of two boreholes at Winterton Water Treatment Works (WTW) in North Lincolnshire, detected traces of two ingredients commonly used in pesticides.

The boreholes were immediately taken out of use and an interim solution to source drinking water from an alternative supply was put into place. The elevated levels of Bentazone and Clopyralid were, after an external investigation report was conducted, thought to originate from the handling and filling area in the farm yard.

Shown below are the Source Protection Zone (SPZ) and the Safe Guard Zone (SGZ).  These are the likely source areas for the boreholes which feed Winterton WTW. 

Winterton Source Protection Zone Map. Source: Environment Agency

Pesticide pollution is one of the biggest risks to water quality.  Due to certain pesticides such as Metaldehyde and Clopyralid being extremely difficult to remove via traditional water treatment methods.  Drinking Water standards state that no individual pesticide will exceed 0.1µg/l (0.1ppb).  This is an extremely small amount and equates to a single stem of hay in 111,000 bales, or 1 grain of wheat in 390 tonnes.

With the likely source being pesticide lost from a farm yard, Anglian Water adopted an innovative, catchment management approach.  Working with 7 farmers located in the SPZ and SGZ to improve the pesticide handling facilities within farm yards. The work focused on ensuring spills and drips are contained.  As well as pollution risk being managed at its source by preventing it from entering the water in the first place. Kelly Hewson-Fisher is part of the agricultural team at Anglian Water and led the catchment management approach with the farmers.