Help us hold Thames Water to account. The company plans to spend £1.8bn to cut spills to rivers from 26 sewer overflows in London. 

But we have no idea if this is value for money or if they have chosen the best solutions.

These sewers discharge when too much rain flows into them.

Cities around the world are creating vegetated areas, e.g. lots of small basins, to hold the rain (more info here)

But our investigations have found Thames Water isn’t planning to do this. Instead it wants to increase the size of the sewer pipes. This isn’t the best option as these can still be overwhelmed. Water companies agree and so does the Government!

Creating raingardens like the one below also reduce street flooding, cool down neighbourhoods and reduce air pollution.

Rains flows into the garden not sewers

Rain flows over the dropped kerb into the small basin full of plants. This cuts the amount of water entering the sewer.

Cities like Philadelphia are using green infrastructure like this to reduce sewer spills.

Photo of a raingarden in Enfield, London.

Frustratingly Thames Water has another plan to reduce the number of homes that are flooded by sewage. For this problem it will use vegetated areas to stop rain getting into sewers.

Two plans, unconnected, means greater costs. We want the company to combine these plans, which would be cheaper, cause less disruption and be more resilient.

We need people to press Thames Water into revealing how integrated their plans are or if they have explored the best options. Send our legally binding information request:

To EIR.Requests@thameswater.co.uk 

Dear Thames Water,

In your announcement on the 13th March 2025, you said £1.8bn will be invested over the next 5 years. It states that 25 storm overflows on four rivers will see investment. This is part of your Storm Overflow Reduction Plan.

Under the Environmental Information Regulations 2014 I would like to request the following information:

  1. Can you provide me with a list of the 25 storm overflows?

  2. Can you send me the Storm Overflow Assessment Framework investigations for all 25?

  3. Were green infrastructure solutions developed for all 25 overflows?

  4. If yes, can you send me the details of the green infrastructure options?

  5. Of the 25 storm overflow sites, how many will use green infrastructure to reduce spill frequencies?

  6. Of the 25 that Thames Water has not decided to use green infrastructure, what are the options to be used?

  7. In your Drainage and Wastewater Management Plan you say you will create green spaces to take the rain that falls on 7,500 hectares of impermeable land by 2050, will this be integrated with your Storm Overflow Reduction Plan? This would be more cost effective and have multiple benefits. 

 Electronic communication is fine.

 Yours faithfully,