Image credit: Sue Illman

SuDS on every street

After waxing lyrical to MPs on the Environmental Audit Committee about how SuDS can deliver a raft of multiple benefits whilst helping to take water out of combined sewers, Alastair Chisholm sets out his vision for SuDS on every street.

Imagine there was an approach to something (with apologies to my drainage engineer colleagues who are wonderful of course) as boring and mundane as surface water drainage that was so multi-dimensional, it could help deliver against many of the highest profile government priorities on the environment in one go.

Imagine there was an approach which, if done well, could provide a major contribution to ensuring that our towns and cities are resilient to the economic and social damages which are projected to grow significantly as a result of climate change.

An approach which would help to reduce the urban heat island effect during the heatwaves we’re predicted to see far more of, but which would also, when those heatwaves break as more intense rainstorms, store and process considerable amounts of the surface water that would otherwise flood our streets, homes and businesses.

(This of course is the surface water that as a result of new developments and urban infill has less possibility of draining away naturally and so is an increasing hazard which is causing combined sewer overflows to discharge too frequently.)

Not only that, but this approach could filter out many of the hydrocarbon pollutants from traffic, which are washed off roads and other hard surfaces during those storms, before they reach our watercourses.

And they’d do the same with microplastic pollution from tyre crumb which is such a big contributor to the overall load of microplastic pollution in our environment.

In addition, they would help to filter airborne pollutants from the air around these roads.

Furthermore, they would add beauty to our built environments – a key priority within government’s planning reforms and proposed National Model Design Codes – creating places with ready access to green and blue infrastructure that’s so valuable for physical and mental health and wellbeing.

And last but by no means least they would contribute to nature recovery – potentially biodiversity net gain – in the urban setting.

This nature benefit can be delivered both directly through their composition as planted engineered features, providing in-situ habitats for pollinators and other invertebrates which are so in decline at the moment. But also, through cleaning the water which drains and percolates through them, so that when it reaches watercourses it recharges and nurtures them, rather than polluting them.

Imagine if designed and delivered well, this approach could be cheaper to construct and to maintain than the conventional way of doing things, with buried pipes and concrete. And lower in carbon too!

Too good to be true?

You could be forgiven for saying that all this is too good to be true; there must be a catch.

Well, honestly, genuinely, hand on heart there isn’t really, it’s real. And it’s eminently possible – if we want it. This approach – these structures – are what we collectively refer to as sustainable drainage systems, or SuDS.

They’re highly adaptable to different sites and conditions. And they’re superbly multifunctional (because they use all kinds of different components that do different things and can be sized appropriately).

Sure, they’re a different way of doing drainage but not that different really. Awesome people have been putting in great multifunctional SuDS in pockets across the country – and the world – for donkeys years.

They’re the sustainable way of doing drainage, whilst delivering so much more, for less. And with the double whammy of more climate change-induced, intense rain storms allied to urban creep and urban infill, surface water flood risk is projected to grow more than most other forms of flooding. So, we absolutely have to be doing SuDS far better, everywhere. Don’t get me wrong, they’re not a silver bullet; we’ll always need big pipes and storm tanks. We just need a helluva lot more SuDS.

At last, our piecemeal English approach to delivery has got us to the stage where most new developments feature SuDS. But too often they’re half-baked approximations of what they could be. And, sticking them in new developments is great, but that’s just not making the currently unsatisfactory flood risk and water quality problems no worse. It’s not taking us anywhere better.


To make inroads into these challenges, we need to retrofit SuDS. Widely. SuDS on every street should be something anyone and everyone should want to see. Modellers can work out exactly where they’ll be most effective. Calculators can work out where they’ll deliver the biggest range of benefits to local communities and the environment. ‘Distributed SuDS’ is a thing. And a thing we should be seeing far more of.

SuDS on every street is the no-brainer backbone of a future climate resilient nation which also has recovering nature, beautiful and vibrant places to live and work, cleaner air and water, healthy communities.

To get there we need to change a few things around the strength and alignment of policy and regulation, around how funding can be accessed, and around the level of appreciation in society of just how great these things are so everyone wants them. It’s about as far from rocket science as you can get. So, let’s make it happen…

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