Urgent need to de-pave London

There is now an urgent need to recreate London as a ‘Sponge City’. Fifty years ago, London was like a sponge, soaking up rainfall into the ground. But more and more paving-over means far too much rainwater now runs off into sewers.

The system is completely overwhelmed, leading to increased flooding and pollution in our rivers and waterways.

• The main benefits of sponge cities are flood prevention and water storage. By filling cities with green spaces which absorb water, there are natural systems in place to prevent and control flooding. Natural systems not only catch the water, but store and purify it, alleviate water shortage, support habitat and biodiversity, and keep cities cool rather than asphalt-heavy cities which insulate heat.

In our Manifesto for the 2024 London Mayoral Election, we ask for the new Mayor to… Organise Emergency Rain Garden Construction of the 357,000 rain gardens* Thames Water says we need to hold water from heavy rainfall and avoid flooding and water pollution, with completion by 2040 (and the majority built by 2035). The current Thames Water target is for these to be installed by 2050 but we and other flood managers and environmentalists we’ve consulted believe they need to be installed much sooner. (*Each rain garden would need to take rainfall from 200sqm of ‘grey’ space – usually a road.)

Though there is a huge amount of work going on, there is still no clear delivery plan in place. The GLA and key organisations need to get behind a delivery schedule and plan to support widescale roll out of SUDS in London, in an appropriate timeframe. Specifically we are concerned that:

• although Thames Water’s Drainage and Water Management Plan sets out a target for 7,598 hectares of impermeable surface to be managed by SUDS in London by 2050, the plan proposes most of these SUDS will be delivered in the period 2040-2050 and this is too far away
• while Thames Water has suggested in a Technical Appendix more detail than in their draft plan how they aspire to deliver this in partnership (and we understand water companies’ Price Review 24 Business Plans should include specific measures to increase the delivery of at-scale SUDS solutions), this plan is currently aspirational and does not detail how targets for SUDS will be delivered
• there is a reliance on ‘market based’ opportunities which will be complex to deliver without a clearly defined, multi-agency approach with strong leadership
• there is a focus on sewer overflow work (end of pipe), pushing flood risk management work (SUDS) back (despite SUDS helping with sewer overflow)
• ‘end of pipe’ solutions are relatively expensive, singular solutions and, in fact, strategic SUDS will ultimately be needed so this approach will mean Thames Water customers will end up paying twice.

We have had informal, though detailed, discussions with a range of statutory and non-government organisations and discovered there is widespread concern about these issues, but also and a strong appetite to come together to find a solution. There is a strong understanding of, and a lot of agreement on, what is needed to deliver SUDS-creation targets within a 15 year timeframe. There is a collective view that it is achievable and can tackle what they see as the key barriers including:

• addressing skills gaps
• leveraging funding from the many organisations which stand to gain from SUDS delivery
• enabling those organisations to benefit from the efficiencies delivered by working together.

At CPRE London we are focussing on

• raising the profile of the need for urgent action, including the reasons why its needed, and asking for a detailed plan for how SUDS will be delivered
• emphasising the links to the Mayor’s Transport Strategy because SUDS or ‘rain gardens’ can help deliver mode shift targets by dramatically improving the walking and cycling environment and reducing space given to car parking
• tackling related issues like paving-over of front and back gardens which is exacerbating the problem while also enabling car parking and (de facto) privatising kerbside space in the front of a house where a driveway is needed. We are demanding a repeal of the law which forces local councils to allow householders to convert their front garden for parking in most circumstances. (More on Protecting Front Gardens and our blog about Richmond’s policy shift.)