Benefits of sustainable drainage systems go beyond making urban areas 'rain-proof'

min read time
2023-05-26 13:09:03




 Friso Klapwijk is urban climate resilience director with Wavin and recently took part in the panel discussion on “Making SuDs a  universal measure to  reduce flood risk” at the NCE Flood Resilience conference. In this article he explains how SuDS (sustainable drainage systems) can be used as part of  a holistic approach to water in our urban environments.


With Defra’s decision the implement Schedule 3, sustainable drainage systems (SuDs) and the water held within, will become a crucial part of designing new developments for towns and cities.

As a result, we need to start thinking about the impact SuDs can have and change the conversation about urban flood resilience being solely for the management of heavy rainstorms and increased impervious surfaces. This is a big issue, with more at stake when it comes to water management.

Only 3% of the world's water is suitable for drinking and most of that is locked up in glaciers and ice caps. It is expected that drinking water shortages will impact many parts of the UK by 2030. Interestingly, we currently only consume around 10% of our drinking water, it therefore makes total sense to look for different sources for some of our other day to day tasks. Currently, 25% of our household drinking water is flushed down the toilet with irrigation, laundry and dishwashers also big culprits for hemorrhaging our clean drinking water supply unnecessarily. Rainwater is the most obvious and simple solution for this.

However, rainwater isn’t a finite supply. Droughts are already hitting some parts of the country with many water companies imposing temporary water bans last summer, following the driest July on record since 1935. The Environment Agency estimates that summer rainfall is expected to decrease by approximately 15% by the 2050s in England and by up to 22% by the 2080s.

We need to look holistically at water in our urban context. Just using SuDs as a flood resilience measure is too technocratic and single targeted. It risks missing an opportunity to hit multiple birds with one stone. SuDs can be a true driver for water circular design, but they need to be multifunctional, smart and repositioned as an asset to general homeowners.

Most stormwater solutions are empty and unused 95% of the time as we only design them for use during heavy periods of rainfall and infiltration. By repurposing them for water reuse, SuDs will play a role in household water levels year-round. This multifunctional approach, however, requires an over-arching design conversation and understanding of smart SuDs capabilities.

It is important to know how SuDs function. Especially when the number of SuDs across the UK grows, their impact on the water system will also increase. The dynamic between private water companies and the public will also change when rainwater is given the purpose of reuse, with data and control starting to play a crucial role. As this is a new field for everyone, it is important to start investing in sensors and smart systems.

Wavin’s solutions such as the PolderRoof are examples of smart SuDs. Wavin’s software platform provides a digital control room. In Rotterdam, we converted a static pond into a retention pond, simply by connecting the municipal forecast system to a pump station: we can therefore lower the water table prior to an expected rainstorm, creating at additional 200m3 storage capacity.


SuDs are currently positioned as a technical solution for flood resilience. This is in line with the tendency over the last 150 years to outsource water management to professionals. But shouldn’t water management be every resident’s responsibility? After all everyone has a vested interest in ensuring we have enough drinking water to go around.

SuDs could reconnect the public to water, but we need to talk and act differently. We need to re-engage them and get them thinking about water as an asset to be saved. A different name would help. SuDs is a typical civil engineering acronym which will mean very little to most people in the UK. In Amsterdam, the term “rain-proof” was introduced. And it worked. To become rain-proof is now a common saying in neighbourhoods across Amsterdam. In Belgium, rainwater reuse is also fully embraced by the public. It is not phrased as a stormwater solution, but as an alternative source of water within every household.

I am passionate about creating water circularity and championing rainwater reuse in all our designs and technology to assist in protecting water as an asset for future generations. It is time we used the knowledge we have as professionals to help the public understand their role in this too.