Make London a 'Sponge City' Event

IN-PERSON EVENT at the Gallery, Cowcross St

CPRE London panel event on urgent need for new wetland areas and rain gardens in London, for river health .. and much more. 

The next four years are critical to tackling flooding and water pollution in London. To address these problems, London must urgently become a ‘Sponge City’. But how – and why? And how can Londoners with front or back gardens help? Alice Roberts from CPRE London explains.

The problems

• Flooding. London used to be like a sponge, soaking up rainwater. But building and paving mean rainwater now runs into the drains – and they are failing to cope. See this BBC News report from 2021.
• Sewage pollution. Rainwater and sewage drains are combined in most of central/inner London. Unable to cope in heavy rainfall, they overflow into rivers, taking raw sewage with them. (Here’s a great summary from London Waterkeeper on sewage pollution.)
• Road run-off pollution. Rainwater from roads and parking lots picks up oil and heavy metals from vehicles, and microplastics from tyres and road markings. In much of London this enters ‘road drains’, flushing pollutants straight into rivers. (Here’s London Waterkeeper again on run-off pollution.)

Solutions

A Sponge City manages these problems with greenery instead of relying solely on drains. ‘Rain gardens’ and wetlands capture, retain and absorb excess storm water, and filter it. (Bonus – they also support wildlife, make our streets more beautiful and help with urban cooling). Here’s Arup on sponginess and why it matters.

Cities as diverse as Shanghai, New York, Berlin and Cardiff are becoming sponge cities. Read about Cardiff.

Rain gardens are a super-effective way to create a sponge city: they stop water flowing into sewers and filter road run-off pollution. They are engineered to capture, hold on to and filter water from an area roughly ten times the size of the rain garden itself.

In recent years Enfield Council has installed many new rain gardens like this newly planted example in Warwick Road, Bowes. However, Thames Water say London needs 357,000 rain gardens to stop sewers being overwhelmed

London needs a massive drive to put in beautiful new rain gardens. Thames Water say we need a staggering 357,000 to ensure sewers aren’t overwhelmed. The new London Mayor must coordinate an emergency programme of rain garden construction. This video is a great summary.

And we need many more urban wetlands – which are of course also a massive boon for wildlife. Here’s Thames21 on what and why.

Front gardens also need to be reinstated, so water doesn’t run-off into the sewers, but is absorbed instead. Read more from London Waterkeeper.

Londoners – you can help by de-paving your front garden.

And Londoners can help by installing ‘SUDS planters’, to capture and hold rainwater from roofs, in their front and back gardens. Installing water butts will help too. Here’s Meristem Design explaining ‘SUDS planters’.

The Event

CPRE London is calling on local authorities to work with relevant parties to organise emergency rain garden construction. There is a need for sustainable urban drainage needs assessments as standard when roadworks and streetscapes are being updated of the need for rain garden creation.  We need a massive acceleration in their creation to support both flood risk reduction and improvements in water quality.  

Learn more at this event which will include networking opportunities for people interested in this important issue.

Speakers will include:   

Alice Roberts, Head of Campaigns, CPRE London 

John Bryden, Head of Improving Rivers, Thames21 

Joe Pecorelli, Programme Manager, ZSL (Zoological Society of London)

Chaired by Anna Taylor, CPRE London

Free tickets on CPRE webiste