What are pesticides?

Pesticides are chemicals that are used as weed killers, insecticides, fungicides and other similar purposes, and the term refers to a wide range of substances and products. Rivers and ground waters may contain traces of pesticides as a result of agricultural use (pest control on crops) and non-agricultural use (herbicide for weed control on highways and railways).

What is being done to keep pesticides out of drinking water?

National regulation in England and Wales compels water companies to comply with strict health-based standards. Water companies are required to take regular samples for pesticides likely to be present in the water supply and concentrations must stay within the prescribed limits.

Over the last three decades water suppliers have invested in advanced water treatment using activated carbon, sometimes in combination with ozone, to safeguard drinking water supplies. Alongside this, longer term wider efforts are underway to encourage more targeted and careful use of pesticides, which will result in improved river and ground water quality.

Water companies are required by law to assess the risk to each of their water sources from pesticides and monitor the raw water for those that could be present due to use in the local water catchments. Water suppliers work with farmers and other land users in water supply catchments to encourage safe use and storage of pesticides to reduce the risk of water sources being contaminated.

What are the drinking water quality standards?

The maximum permitted concentration for most individual pesticides in drinking water is 0.1μg/l (microgrammes per litre). This corresponds to a concentration of 1 part in ten billion. It is not a health-based standard; it is based on the limit set by the European Commission in 1980 to reflect the limit of analytical methodology at the time and as an environmental policy to generally limit pesticides. The Directive also set a standard of 0.5μg/l Total Pesticides (the sum of all the substances detected in a sample). There are stricter separate health-based standards for four named organochlorine pesticides whose use is now banned in the UK. These standards have been incorporated into national legislation and remain in place even as the UK leaves the EU.

Summary statistics on the results of pesticide testing by water suppliers’ can be found on their websites. You can obtain details of the results for your local water supply by asking your water supplier for a free water quality report. You can find the contact details for your water company on your bill or on our website.

Who controls the sale and use of pesticides?

The Health and Safety Executive’s Chemicals Regulation Directorate is the competent authority for the prohibition and approval of pesticides in England and Wales. The Environment Agency is the competent authority for prevention of pollution of rivers, lakes and ground water.

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