Catchment management

It's important that we work to improve the quality of the raw water we then treat to supply to our customers.

Catchment management 

What is it?

15 per cent of our raw water supply comes from the River Eden and is stored in our Bough Beech reservoir in Kent, prior to treatment. Every year, between September and April, we abstract water from the River Eden into Bough Beech reservoir where it is stored before going through the treatment process. We work hard to manage our water and its quality and continually look to improve catchment management within our area.

Catchment management aims to prevent the pollution of our rivers, streams and aquifers at the source rather than relying on ‘end of pipe’ solutions, such as more water treatment processes. It is also a more sustainable and cost-effective way of tackling water pollution, as well as delivering on other environmental and community benefits.

‘Catchment area’ describes where rainfall naturally collects and feeds into the source.  Our surface water catchment, known as the Eden catchment, covers 220km2 with agriculture being the primary land use which has an impact on our surface water reservoir at Bough Beech.

One of the biggest water quality challenges is from metaldehyde, the active ingredient in slug pellets. To tackle this, we liaise with local farmers and agronomists to promote the use of an alternative product and are currently looking into additional measures that could help reduce pesticide and nutrient concentrations in the catchment.

Groundwater catchments

Groundwater catchments are known as Source Protection Zones. With 85 per cent of our raw water coming from the deep aquifers in the chalk of the North Downs or the large deposits of greensand south of the Downs, using the Environment Agency’s Groundwater Source Protection Zones (SPZ) we analyse surrounding land uses, such as industrial, residential and agricultural to identify potential risks. 

One of our biggest challenges with groundwater is nitrates from both rural and urban sources for example, septic tanks, fertiliser application and sewers.

Our commitment

We are committed to actively engaging in the catchment to improve water quality. To ensure we meet our commitment we:

  • Take regular samples to give us a greater understanding of the water movements and pollution pathways
  • Work closely with others, including land owners, farmers, National Farmers Union, Natural England, Environment Agency, Rivers Trusts and Wildlife Trusts, to raise awareness of and confront the challenges we face
  • Identify ‘high risk’ areas of pollution and where we should focus our efforts using Geographic Information System (GIS) mapping techniques
  • Investigate, identify and address as many sources of pollution as we can
  • Support our area's catchment partnerships 

Working with farmers

It's important for us to work closely with farmers to raise awareness of the issue of nitrates and pesticides in water.                     Find out more about:


Use the BASF wHen2g0 Smart Tool to help improve application timings of metazachlor and quinmerac. This tool takes into account location, soil type, soil moisture and weather to give improved water stewardship advice for these herbicides.

Download the Autumn 2019 Eden Newsletter and email catchment@seswater.co.uk to receive a digital copy.

Improve water quality in your area

Contact us

For more information please contact the Catchment Team on 01737 785631 or email catchment@seswater.co.uk.