University team working to improve drinking water quality

The University’s Agriculture and Environment Research Unit (AERU), are part of a team working with the UK water industry to improve the quality of water abstracted for domestic water supplies.

Metaldehyde presents the water industry with a significant challenge in terms of meeting its obligations under the Drinking Water Directive, which sets a limit of 0.1μg l-1 for pesticide concentrations in drinking waters. In the UK, metaldehyde is the most common molluscicide (slug pellet) used by farmers and gardeners, being applied to around a million hectares of agricultural land per annum, although this varies significantly from year to year, and forms a vital tool in the armouries of many arable producers. The problem is that over recent years it has been detected in drinking water sources at concentrations which are sometimes well above the required standard, and current techniques for treating waters are ineffective against this particular chemical, although they work on many other pesticides. Metaldehyde can find its way into field drains and watercourses either through accidental direct application or more commonly as a result of run-off during high or prolonged rainfall events, particularly in the autumn and early winter. Therefore, although the concentrations being detected pose no threat to human health (toxicological studies suggest that to exceed the acceptable daily intake for metaldehyde, the average person would have to drink more than 1,000 litres of water a day), water companies need to ensure that the legal limits are complied with.

Given that treatment is not an option, the only way forward is to control the problem at source (on the farm), and the University’s Agriculture and Environment Research Unit (AERU) are part of a team (including AECOM, Reading Agricultural Consultants and the Loddon Farm Advice Project) engaged by Affinity Water to investigate a novel approach to encouraging farmers to adopt practices which limit pollution problems. These may include such things as switching to the use of ferric-phosphate pellets, using appropriate cultural controls and/or installing mitigation measures. This project will use a Payment for Ecosystem Services (PES) approach in which Affinity agree to pay farmers a clean water bonus (on the basis that it saves them a lot of money) if they manage to meet certain standards for water quality within the catchment. The work is being carried out in part of the River Loddon catchment in northern Hampshire; and if successful, not only will it provide substantial benefits in terms of water quality, but it could also influence the way in which water companies around the country address this and other issues in the future.

For further information on the project, please visit the project website.

University of Hertfordshire
University of Hertfordshire, 2020.