What is metaldehyde?

Metaldehyde is the active ingredient in many slug pellets and is commonly used in agriculture to protect crops against slug damage. The pellets are usually applied in autumn when soils are wet and rainfall is highly likely.

Why is it a problem?

When it rains, metaldehyde can be washed off the land and enter rivers at concentrations exceeding the Drinking Water Standard (DWS) of 0.1µg/l. This is the equivalent of 1 grain of wheat in 390 tonnes. This is not a health standard, but is a legal requirement that has to be met in every treated water sample tested.

Unfortunately, metaldehyde cannot be easily removed through advanced water treatment processes so we’re working with farmers, land managers and the wider pesticide industry on catchment management approaches to prevent metaldehyde reaching watercourses.

Our approach

We began a catchment management programme to reduce water pollution from metaldehyde in 2010. The projects that we’re currently involved with include:

What is product substitution?

To encourage farmers to use slug pellets that contain ferric phosphate instead of metaldehyde, we’re offering arable farmers in some catchment areas with a subsidy of £1/kg of ferric phosphate slug pellets applied on autumn sown crops, as an alternative to metaldehyde slug pellets.

When does the subsidy apply?

You can claim the subsidy for ferric phosphate slug pellets applied to your autumn-sown crops from 1st August until the deadline of the 7th December 2018. You will be paid in Spring 2019.

How to apply and claim?

Please register and request a claim form through your project partner, or email

Note: to complete the form you’ll need to know your cropped area (by crop), and the amount of ferric phosphate applied to each crop. You’ll also need a copy of your receipt (proof of purchase) to Promar International by email or post.

Application deadline: 7th December 2018

What is Payment for Ecosystem Services?

PES schemes involve payments to managers of land, or other natural resources in exchange for the provision of specified ecosystem services, over-and-above what would otherwise be provided in the absence of payment

When does the subsidy apply?

The project aims to recognise farmers as producers of “clean” water. That is, water below the drinking water standard of 0.1µg/l (micrograms per litre) for metaldehyde.

How to apply and claim?

Please register and request a claim form through your project partner, or email

Application deadline: 30th September 2018

Other projects

Swales trial

We’re also investigating if slowing down runoff through the use of swales (shallow ditches) can reduce the amount of pesticides in the watercourse.

If you’d like more information on our catchment management projects, please email us at