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.
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