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Natural drainage: a whole lot more than drains

February 2015

I don’t know about you but I seem to get caught up a bit in my life, waking up, breakfast, work, exercise, cooking, washing up, ticking things off the “to do” list, going to sleep. Little things start to irk me and to stress me out: I shout at my computer, I want things to happen faster and I swear when I spill my tea. That's when I realise, this weekend I have to get out and go for a walk. When I climb a grassy hill, walk along the river or a coast path or the canal I feel myself take a deep breath of air and I start to relax. I forget about all the silly things that were getting my goat and I just enjoy myself and remember that this is it, there is so much more to life than my every day, there is so much more than “me”.

I truly believe that this ability for natural landscapes to make us feel better is one of the hugely important values of urban green space for those people who can’t get as out into the countryside, as I am lucky enough to be able to do. The opportunity for natural flood management in the urban environment to provide such spaces is massive. We could put natural drainage systems into all new developments and there are many opportunities for retrofitting such as into schools and onto hotel roofs and walls. Not only do we provide a solution to our overloaded sewage drainage and reduce the risk of surface water flooding but we provide people with a connection to nature that has been shown to improve health and well-being. Having natural drainage systems in schools can provide a valuable space for outdoor learning and learning about natural processes such as the water cycle. Even schools with only limited outdoor space can accommodate these systems (see

Natural drainage means space for nature

[caption id="attachment_375" align="alignright" width="1300"]Black Redstart Black Redstart © Laurence Arnold[/caption]

There are many small, cheap ways which natural drainage systems can be designed, built and managed to benefit wildlife and provide vital patch habitats, providing stepping stones and connections for wildlife in the urban environment. Native wildflowers can provide an urban haven for pollinators such as bees and butterflies, ponds with shallow edges can encourage frogs and newts and all provide a much prettier environment for people to enjoy than concrete and drainpipes. Green roofs have even been known to provide a suitable habitat for ground nesting birds, including black redstarts in London. The black redstart is one of our rarest birds. It's on the amber list of Birds of Conservation Concern and it's thought that there are fewer than 100 breeding pairs in the country.

Natural drainage can help reduce flooding

Many of our traditional sewage systems are already at capacity. Given the predicted increases in development, demand and climate change on our aging infrastructure will only result in increasing our risk of surface water flooding. This results in sewage and polluted water not only going straight into our rivers and seas but also into people’s homes. Natural drainage systems mimic natural processes and reduce the amount of surface water getting to our traditional drainage systems and reduce the risk of surface water flooding. They predominantly act by slowing down water flow off our roofs, pavements and other hard surfaces which usually direct water as fast as possible to the nearest sewer. They also include soil and plants that act as filters to remove pollution along the way. Examples of SuDS features include reed beds, swales, filter strips, ponds, rain gardens, rainwater butts, permeable paving (paving that lets water soak through to the ground) and living green walls and roofs. By providing these spaces and growing plants they can help to address air pollution and act as a cooling mechanism reducing the increased temperatures found in urban areas which are due to the large areas of hard surfaces like roofs and roads.

Why aren't we creating more?

So, it seems like a no-brainer to me, good use of money all around for people and wildlife. Yet the government are completely failing to lead the way, back tracking on previous commitments to ensure that these systems are put in place in new developments. Why, I can only speculate, but the reticence to put these systems in ultimately results in more flooding for people and polluted water for our environment. That does not seem fair to me. Not only that but the government are failing to commit to retrofitting and also to making sure that natural drainage systems are designed so they provide these multiple benefits I described around being amazing spaces for people and wildlife to enjoy.

What you can do to help

[caption id="attachment_385" align="alignright" width="1300"]Black Redstart Hollickwood Primary School, London, part of the WWT SuDS for Schools project © Sacha Densch/WWT[/caption]

The RSPB and WWT have written guidance on how to design and manage these natural drainage systems (also known as sustainable drainage systems) to benefit people and wildlife (available to download from (see In addition it is hugely important that these ideas get inputted into local spatial plans, greenspace strategies and flood management strategies. These are all open for public consultation when they are being compiled so everyone can play their part in influencing these documents. An overarching strategic view is hugely valuable if we are to provide a network of connected habitats within the urban environment to benefit wildlife. But we don’t always have to look big scale. What can you fit in your garden, up your wall or on your roof?

Hannah Freeman

Conservation Policy Officer, Wildfowl & Wetlands Trust (WWT)