Soak Up Lambeth: Creating Sustainable Drainage Systems across Lambeth

As climate change impacts increase, we have seen more frequent surface water flooding in the borough.

This puts further pressure on our sewer system, which had not been designed to cope with recent increases in rainfall. Creating Sustainable Drainage System (SuDS) schemes will help reduce climate change's current and future impacts on flood risk.

As the impacts of climate change increase, we have seen more frequent surface water flooding in the borough, putting further pressure on our sewer system, which was not designed to cope with recent increases in rainfall.  

Surface water flooding is one of Lambeth’s most pressing environmental challenges, with 8,500 properties and £121 million worth of infrastructure considered high risk. A warming climate means more regular and intense periods of rainfall, which can make flash flooding more likely.

This intensifying rainfall, coupled with the borough’s high population density and extensive impermeable ‘grey’ surfaces, has placed immense pressure on an outdated Victorian drainage and sewer system.

Instead of allowing rainwater to rush into our drains and sewers all at once, causing them to overload and flood, Sustainable Drainage Systems (SuDS) are used to mimic the water cycle to give the sewers a chance to cope with heavy rain.

SuDS collect rainfall from hard surfaces like roads and roofs into soft landscaped features  such as swales, temporary ponds, and underground storage basins. By making these features nature-based, soil and plants allow the rainwater to soak into the ground slowly. During heavy rain, the SuDS slows the water back into the sewer, so it does not flood itself and the surrounding areas.

These ‘greener’ approaches to flood prevention also improve:

• Air quality
• Biodiversity
• Water quality
• Access to green spaces
• Shading and cool spaces

Lambeth Council created its £6 million Soak Up Lambeth programme, funded with £2.45 million from Thames Water Utilities and further funding from the Greater London Authority, Environment Agency and the Department for Education. The programme will implement SuDS across the borough, targeting areas chosen by flood modelling assessments, highlighting key rainwater capture areas that will have the most impact on reducing flooding further downstream of the Victorian drainage and sewer system that Lambeth relies on.

St Matthew’s Estate

The scheme on St Matthew’s Estate, which started construction in the Autumn of 2024, consists of two swales draining across a length of green space alongside Effra Road. The swales are shallow channels dug into the ground to direct the water flow. The two swales will lead into temporary pools that fill when it rains and slowly drain into the surrounding soil. These channels and pools are designed to direct and collect the water rather than letting it run across the ground's surface and into nearby drains.

The scheme will also include planting to help with drainage and improve biodiversity, such as hedges and wildflower meadow. It will also serve as a recreational space for the housing estate, with information boards, pathways, and a nature trail for children.

CGI images of the new SuDS on St Matthew's Estate

Norwood Park

The regeneration of Norwood Park will include several new swales that will direct the water to nature spaces across the park. The swales are shallow ditches, with frequent dams to slowly direct the rainwater that collects on the ground towards storage basins and ponds. The dams slow the flow of water and create temporary wetland habitats. There will also be a new stretch of permeable asphalt alongside the sports courts that will let excess rainwater drain through the ground into storage underneath and then out to the connected sewer system.

• The new features have been designed to create incidental play by adding logs and paths through and across the swales, encouraging children to take their own trail through the landscape, including through a grass meadow.
• The additional pond to the north of the park will help supply water to the existing nature pond. 
• Native and pollinator-friendly planting has been chosen to support the local habitat.
• Slowing the water down within the park will create more favourable conditions for aquatic wildlife like frogs and toads.

The proposed scheme design for Norwood Park

SuDS on Estates and Schools

Alongside these big schemes, Lambeth Council is also implementing smaller schemes on Benton’s Lane, William Bonney, St. Alphonsus, Myatt’s Field, Stanthorpe Close, and St Anselm’s Court Estates. These schemes are designed to improve drainage and biodiversity in the estates' community gardens and spaces.

Rain gardens are also being constructed on the roads outside Jessop and Archbishop Sumner Primary Schools. These schemes aim to reduce local flood risk and introduce more nature into the school surroundings.