This year's severe flooding has once again highlighted the weaknesses in Britain’s surface water drainage infrastructure – and the need for a strategic Government commitment to plan and invest to avoid future devastation, experts are warning.

The New Year onslaught came with 2007’s summer floods still fresh in the memory – two thirds of which are reported to have been caused by surface water.¹  A “joined-up” government plan and significant investment in so-called “Sustainable Drainage” are essential to plan for the long-term effects of climate change, warn stormwater control experts Hydro International.

The Environment Agency revealed last summer that more than five times as many households were flooded as a result of overflowing drains and sewers than that of river flooding.  To reduce the impact of future flooding, it will be important to provide for increased storage and treatment technology within our existing surface water drainage infrastructure to hold back the rainfall at source.

“Recent enquiries by Sir Michael Pitt, the parliamentary EFRA committee and the soon-to-be announced DEFRA Water Strategy are all welcome responses; but action, planning and investment in surface drainage technology must urgently follow these words,” says Hydro’s Chief Operating Officer, Chris Williams.

“As climate change takes hold we can expect repeating patterns of flooding to become a regular occurrence. The amount and intensity of winter rain are expected to rise steadily, exposing an ever greater number of properties to the risk of flood damage.²  Meanwhile our expanding population is demanding more and more homes – already the Government is committed to building 3 million new homes by 2020. “

“At the same time, the amount of impermeable surface and hard-standing is growing dramatically.  For example, two thirds of gardens in London are at least partially paved over.  When surface water has nowhere to go, it overwhelms our sewerage system, devastates our homes and transports silt and pollutants into our rivers and seas.

“Too many misperceptions still abound about the concept of sustainable drainage, which is hindering its correct and speedy implementation.  Recent comments by Phil Woolas the Environment Minister, together with recent policy changes by Scottish Water, show a worrying lack of appreciation of the technology choices available to efficiently hold back and treat surface water as close as possible to the point of falling.

“It’s fifteen years since Hydro published ‘Urban Drainage – The Natural Way’ highlighting the importance of Source Control and Sustainable Drainage (SUDS), now accepted as a standard principle by many water and planning authorities.  Yet SUDS is still over-associated with “soft” drainage solutions such as ponds and swales, often inappropriate for space-strapped urban areas. 

“Equally, suggestions that householders and developers should no longer have a divine right to create more impermeable surfaces are welcome, but it is not as simple as removing the right to connect surface drains to the sewerage system as has been suggested in some circles.”

“The use of silt control and filtration technology at the point of falling is essential to eliminate silt build up within the sewer, which would make drainage less efficient and increase the need to treat water further down the line.  Extracting stormwater pollution from roads and hard surfaces at source will also become increasingly important.”

“But, there is a disconnect between the sewerage and planning authorities in meeting the European Water Framework Directive’s demand for an integrated approach to controlling and treating water, from the point where it falls through its onward journey through surface drains and the sewerage system and onward through our rivers to the sea.

“Each of the existing stakeholders involved in the UK water cycle, from DEFRA, the EA, through to Water Companies and planning authorities, has a separate role and delineated responsibilities.  This makes it hard to plan a system in which water is treated efficiently at every stage in the process.   A single, unitary authority responsible for stormwater would be the best, if radical, solution.  Otherwise a Government strategy implemented by a strong lead authority may be the answer.”

Hydro International has been a pioneer and champion of sustainable drainage (SUDS) for more than 20 years. The principle is now increasingly widely adopted by UK planning authorities to ensure low-maintenance drainage is installed as close as possible to the point that the water falls, with minimal impact on the local environment.   However, more needs to be done to ensure that SUDs are adopted on a more widespread basis throughout the UK.

Hydro International is a leading international specialist supplier of stormwater control, storage and recycling technologies, including products such as the brand leading  Hydro-Brake Flow Control, Stormbloc or Stormcell  modular stormwater storage systems, Up-Flo™ Filtration and pollution removal systems or StormBank rainwater harvesting.

1: The Pitt Review 2007
2: Future Flooding Report 2004

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