Catchment management

Last reviewed:

Thames Water supplies 9 million customers with an average of 2.6 billion litres of drinking water per day.

This is supplied from both groundwater (boreholes and springs) and surface water sources (rivers).

The contamination of watercourses presents an ongoing problem for all water companies due to the nature of diffuse pollution.

The Thames Water catchment is approximately 11,000 sq. km in area. It includes the River Thames and the River Lee and their tributaries, and can be divided into a number of sub-catchments.

The catchment management approach

The EU Water Framework Directive (WFD) encourages catchment based solutions rather than adding additional expensive treatment at water treatment works (WTW).

Water companies are setting up catchment management initiatives with local stakeholders to identify pollution pathways and work with landowners to address diffuse pollution.

In order to improve our understanding of the catchment, we undertake the following activities:

  • Collect river water samples from over 100 sampling points in Thames Water’s catchment to identify ‘hot spot’ areas where pesticide concentrations are high.
  • Work with the Environment Agency to identify Safeguard Zones.
  • Work closely with the crop protection industry, land owners, farmers and other stakeholders.
  • Investigate the likelihood of agricultural pollution reaching the rivers following rainfall by using information such as soil type, gradient and land use.

These activities provide us with a greater knowledge of the catchment, which allows us to

  • Identify risks
  • Engage with stakeholders
  • Mitigate risks
  • Protect our sources