A landmark project in Brighton is on track to protect 90% of the city’s drinking water from toxic road pollution.
Every time it rains, millions of litres of water wash off roads, carrying a dangerous mix of oil, tyre particles, heavy metals, and microplastics.
This stormwater runoff is a largely unseen but significant pollutant, affecting rivers, wetlands, and groundwater in the UK and across the world.
The threats from roadway runoff are striking. In Australia, about 95% of microplastics in stormwater come from tyres – tiny particles containing with carcinogens that can enter the food chain, posing risks to human health.
In America’s Pacific Northwest, untreated runoff can kill up to 87% of coho salmon exposed to it.
And in England, road runoff contributes to nearly one-fifth of waterbodies failing to meet ecological or chemical standards, showing that the impact of our roads stretches far beyond the asphalt.
In Brighton & Hove, the stakes could not be higher. Over 90% of the city’s drinking water comes from the chalk aquifer beneath the city, a delicate natural reservoir that also supports streams, wetlands and wildlife. Once contaminated, it can be very difficult to clean.
Wild Park rainscape
Now, the Wild Park rainscape – built beside the A27, one of the busiest roads in Sussex – aims to address this problem by capturing and filtering polluted runoff before it reaches the aquifer.
Before construction began, runoff from the A27 was monitored by a team from the University of Brighton to establish a baseline for pollutants.
Studies revealed the scale of road runoff pollution: water in the area contained higher levels of contaminants than recommended.
Lead, a remnant from older fuels, chromium from road markings, and polyaromatic hydrocarbons from tyres and asphalt were all present. Much of this pollution travels as solid particles, which can move long distances, linger in soil and waterways, harm wildlife, and even enter the food chain, posing a threat to human health.
Detailed analysis led by Martin Smith, Professor of Geochemistry at the University of Brighton, and geoscience graduate Polly Walters, showed that much of this contamination could be captured before it reached the soil.
Removing solids alone addresses around 80% of the pollutants, with plants and natural processes handling the rest.
Prof Smith explained: “When polluted water from our roads seeps into the aquifer, it’s not just a scientific problem – it’s our drinking water, our children’s health, and our local environment at stake. Projects like the Wild Park rainscape make sure the water we rely on every day is safe.”
How it works
After six years of planning, the rainscape combines engineered solutions with wetlands.
Water from the motorway travels along a 1.2-mile route, passing through multiple filtration stages before it reaches the ground.
Two vortex separators remove the bulk of solids, while planted basins of reeds and grasses, along with sunlight and microbes, are intended to break down remaining pollutants. By the time water leaves the system, it is clean and safe.
Looking ahead, the university team will continue monitoring to measure the rainscape’s impact on water quality, pollutant removal, and biodiversity.
Their findings aim to protect Brighton’s aquifer and provide a science-based model for cities worldwide facing similar stormwater challenges. The monitoring will reveal how well the system performs and provide valuable insights to guide the design of future projects.
This approach goes far beyond some drainage systems – which let polluted water sink into the ground or enter surface waters – and the impact is wide-reaching.
The rainscape not only filters pollutants but also slows water flow to reduce flood risk, improves local water quality, and creates new habitats for wildlife.
Construction was led by Brighton & Hove City Council, and the project was managed by The Aquifer Project – part of The Living Coast UNESCO Biosphere, which recognises the area’s unique natural and cultural value and promotes sustainable development.
Winning the pollution fight
Ed Santry, of The Living Coast UNESCO Biosphere, said: “The Wild Park rainscape is a perfect example of partners coming together to deliver a valuable project both for nature and people. By embedding valuable research and monitoring, the rainscape will help us in developing future projects to protect our chalk aquifer”.
Brighton councillor Trevor Muten added: “The Wild Park rainscape is a fantastic demonstration of what can be achieved when a range of partners work together to find practical ways of adapting to climate change.”
“The rainscape is a ground-breaking project in more ways than one, harnessing the power of nature to filter out pollution and protect the underground chalk aquifer which supplies much of our drinking water.”
“But it’s much more than that. Using the natural capacity of ponds and reed beds with specially designed infrastructure, the rainscape captures stormwater run-off from roads helping to prevent flooding and provides a stunning new landscape for people and wildlife in Wild Park.”
However, the project isn’t only about tackling pollution – it’s also about people. Wild Park sits in one of Brighton’s most disadvantaged neighbourhoods, and the rainscape is designed to bring wider benefits to the local community.
By creating new ponds and green spaces, the hope is that residents and visitors will find more reasons to spend time there.
