SuDS, not duds: don’t water down rules on floods

Floods will continue to ruin people’s livelihoods if the Government waters down rules on SuDS.

Natural rain absorbing features known as SuDS hit the news earlier this year as one solution to the devastating flooding that hit southern England.

On paper they've been a legal requirement of all new developments since 2010, but the law has not yet been implemented.

Four years on and the regulations have been delayed again by a further consultation that proposes to weaken their effectiveness.

WWT Head of Conservation Policy Jeff Knott says:

“The Government spends £1 billion of taxpayers’ money on dealing with flooding each year and the overall cost to people’s homes and livelihood is far greater than that. We've seen time and again the devastating effects of building on floodplains without considering where the water goes.

“SuDS are not only cheaper than connecting to the drains; done right, SuDS make our environment richer and healthier. The Government committed to SuDS four years ago. The 11th hour is not the time to start diluting their promises to all those flooded home and business owners.”

SuDS encompass various ways to capture rain naturally. This image is from  WWT and RSPB's guide to SuDS for local authorities and developers (c) naturebureau.co.uk
SuDS encompass various ways to capture rain naturally. This image is from WWT and RSPB's guide to SuDS for local authorities and developers (c) naturebureau.co.uk

The consultation is live on the Defra website until 24 October. The proposed changes include exempting smaller developments (fewer than 10 houses or equivalent) and giving developers more influence as to whether rainwater is caught naturally or sent into the sewers.

Since April 2010, when the Flood and Water Management Act was brought in, close to half a million homes have been built in England (1). The average new home in England is 76 square metres (2), making the average roof size 38 square metres. The average annual rainfall is 854.8 litres per square metre (3). Even after adjusting for roofs’ inefficiencies in channelling rain into the gutters, that’s around 11 billion litres of extra rainfall per year (4) that could be being caught and filtered by SuDS that make neighbourhoods more attractive and support wildlife.

The current consultation proposes excluding smaller developments of fewer than 10 properties, which will weaken the regulations’ ability to reduce flooding risk by at least a fifth (5). And it would have a knock on effect on the amount of greenspace in towns and cities (6).

SuDS encompass a range of natural ways to capture rain, from green roofs and ponds to much larger wetland areas. They reduce flooding and pollution and, if built well, can be habitats for wildlife and make our neighbourhoods greener and more pleasant.

WWT has SuDS at its Wetland Centres around the UK and last year published guidance on creating SuDS that support wildlife and communities, as well as helping manage water.

WWT advocates investing in natural wetlands to solve the environmental problems we face now and into the future. It runs nine Wetland Centres in the UK where visitors can see examples of working wetlands in use. It also works as a charity on wetland conservation projects around the world, and as a consultant to corporations and public bodies.

(1) Exactly 446,730. https://www.gov.uk/government/statistical-data-sets/live-tables-on-house-building

(2) http://www.architecture.com/Files/RIBAHoldings/PolicyAndInternationalRelations/Policy/Housing/RIBACaseforSpace.pdf

(3) http://www.metoffice.gov.uk/climate/uk/averages/19812010/areal/england.html

(4) 446,730 x 38 x 854.8 x 0.8 = 11,608,690,041

Efficiency of a standard pitch roof is 0.9. Efficiency of a flat roof is 0.7. As these roofs will be mixed, have used 0.8 as an assumption.

(5) Developments under 10 properties accounts for 29% of building (p.15) https://consult.defra.gov.uk/biodiversity/biodiversity_offsetting/supporting_documents/20130903Biodiversity offsetting green paper.pdf

Single property developments are exempt from the regulations anyway and account for about 10,000 homes per year https://www.gov.uk/government/policies/increasing-the-number-of-available-homes/supporting-pages/self-builders which equates to about 9% of building.

(6) Developments under 10 properties are more likely to be in-fill developments: developments on small bits of available space in built-up areas. These are the few patches of urban landscape that aren't already contributing to flooding and may still be supporting local wildlife. Excluding smaller developments is likely to have a disproportionately negative effect in weakening the regulations.

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