Twenty 4 twenty: Sustainable drainage

Thames Water will be contributing £20m over the next 5 years towards projects delivering sustainable drainage such as rain gardens, swales and permeable paving.

By the time we have completed the programme, we hope to have removed around 20 hectares (so around 30 football pitches) of hard, impermeable surfaces such as concrete and asphalt. This will help to reduce the risk of sewer flooding and pollution following heavy rainfall.

This initiative will build upon sustainable drainage projects that Thames Water has successfully been involved with to date. For example, in Dulwich Park, Thames Water contributed £2m towards a large sustainable drainage project in partnership with Southwark Council. The project was completed in 2014, has reduced the risk of sewer flooding to over 100 properties in the area and has won several awards.

We have recently written to all 33 London Boroughs to learn more about sustainable drainage projects that are under development across the Capital and are also keen to work with the Mayor, the Environment Agency, private business and non-for profit organisations.

Our focus is on areas served by ‘combined sewers’ - those that collect not only the foul water from toilets and sinks, but also surface water that lands on roofs and hardstanding areas when it rains. Given that almost all of the sewers in central London are combined, collecting both foul water and surface water, we expect that at least half of the £20m will be put towards projects in London.

This is the start of a long-term programme to help reduce the strain on the sewerage network as the population grows, our towns and cities become more urbanised and our climate changes. If the programme goes well, which we think it will, we’ll do more.