Slug it Out is part of Anglian Water's way of working. The campaign is aimed at reducing the levels of the slug control pesticide Metaldehyde in our region’s waters before they reach our treatment works.

Although harmless to humans, Metaldehyde is very difficult to remove at water treatment works and meeting tough EU targets on it is a real challenge for the region.


The regulatory level of Metaldehyde stipulated by the European Union’s Water Framework Directive is 0.1 micrograms per litre (or parts per billion) in treated water. This is the same as one drop in an Olympic sized swimming pool or 1 second in 320 years. Levels in reservoirs in our region regularly exceed this and removing this at the scale required across our region is not currently possible or practical. On top of this, Anglian Water spends large amounts of money removing pesticides from drinking water at our treatment works – this raises customers’ bills and wastes energy.

The Slug it Out trial has been in place since 2015 involving around seven key reservoirs to incentivise farmers to stop using metaldehyde and use other methods to control slugs instead. The farmers all took part voluntarily in the scheme and received payments to cover their costs and for taking part.

The reservoirs involved are Alton Water in Suffolk; Ardleigh Reservoir near Colchester; Hollowell Reservoir, Ravensthorpe Reservoir and Pitsford Water in Northamptonshire, Rutland Water in Oakham and Grafham Water in Cambridgeshire. Covenham reservoir was involved for one year in 2016/17.

Results show that the Slug it Out trial has been successful; engaging with 225 farmers and leading to a 96% reduction in the level of metaldehyde across the region. Importantly, farmer engagement in the Slug it Out trial has been maintained each year and in addition to the land in the natural catchments involved in the Slug it Out trial, there has been a shift to farmers stopping using metaldehyde in land in our pumped catchments as well – effectively expanding the area in our region without metaldehyde and further helping to protect our watercourses. This was the case at Lamport Hall in Northamptonshire where in 2017, Lamport Hall switched their whole in hand farm to ferric phosphate – not just the land in the Slug it Out trial area, and commented that they believed it worked ‘just as well (as metaldehyde)’ and felt that using an alternative to metaldehyde meant that applying slug pellets whilst following product stewardship guidelines was easier.


As well as taking part in the Slug it Out trial, our network of farmers and agronomists have also provided information on product usage, cropping plans and key business risks to allow Anglian Water to continue to work with the farmers in our region at a business-business level. The working relationships developed as part of the Slug it Out scheme have also allowed farmers to take part in on farm trials which has helped further our understanding of alternative methods of slug control and provided ideas that would help us work with farmers all across our catchment to protect water quality.


We are very proud of our work with farmers across our region as their co-operation is fundamental to the success of Slug it Out. At the moment, metaldehyde is still legal to use in the UK and as such, we will be entering into our sixth Slug it Out season from June 2020.


Reservoir factsheets

Below you will find a factsheet on each reservoir in the trial project.