One drop of pesticide in Olympic pool enough to exceed limit in 30 km of stream

Pesticide contamination of drinking water sources quadrupled since 2014, and has been linked to farmers using MCPA herbicide to prevent the overgrowth of rushes which can render their land ineligible for EU payments.

Records of pesticide contamination in drinking water supplies between 2007 and 2016 show incidences shooting upwards, reaching nearly 80 in 2014, nearly 160 in 2015, and about 140 in 2016, compared to no more than 40 in each of the seven previous years.

Pesticide exceedances peaked in May and September, and about 70% of exceedances were for the MCPA herbicide, widely used in agriculture, but also in amenity use (on golf courses, parks, sports grounds, etc); and for amateur use (home gardens).