Demo case 5

Combatting Toxic Road Runoff

Plymouth, United Kingdom

Context

Urban runoff from roads and vehicles carries a complex mix of chemicals and pollutants into the wastewater system and, where untreated runoff reaches the freshwater environment directly, into local rivers and coastal waters. The impacts on water quality, wildlife, and bathing waters can be significant.
The Plymouth demonstration combines online and offline sensor technologies with citizen-science monitoring to map the mobility of pollutants and identify where they enter the river and sewer network. This will give SWW and partner stakeholders a clearer evidence base for targeted interventions, support timely action to protect water quality and ecosystems, and raise public awareness of the impacts of urban runoff.

Key facts

Using a combination of professional sensors and “citizen science volunteers”, the project maps how road pollution moves through the city and into the sea.

Potential Impacts

Evidence and monitoring

A validated, replicable methodology for monitoring urban road runoff using a combination of fixed sensors, mobile/offline sensors, and citizen-science observations.
Improved spatial understanding of where pollutants enter the river and sewer network in Plymouth, including verification of previously unverified high-risk outfalls.
A baseline dataset on urban runoff pollutant loads that can inform future regulatory monitoring and investment cases.

Operational and infrastructure

Better-informed decisions for interventions across the drainage network, including prioritisation of CSO and surface-water asset upgrades.
Earlier detection of pollution events during extreme weather, supporting faster operational response.
Evidence to support nature-based or SuDS-style interventions where grey infrastructure alone is insufficient.

Environmental

Reduced pollutant loads reaching theRivers Plym, Tamar, which feed into the Plymouth Sound, will provide downstream benefits for bathing waters, shellfish waters, and protected habitats.
Improved conditions for freshwater and estuarine ecosystems, contributing tothe Water Framework Directive (WFD) waterbody status improvements.

Public, partnership and policy

Greater public awareness of the link between everyday road use and river/coastal water quality.
A working model for collaboration between a water company, local highway authorities, National Highways, and citizen-science networks – addressing the fragmented responsibility for road drainage.
Transferable evidence and tools that other UK and EU utilities can adopt in their own catchments, contributing to the wider QleanUP replication objectives.

Citizen science specifically

A scalable citizen-science protocol for urban runoff that complements existing Westcountry CSI activity.
Increased volunteer engagement and stewardship in urban Plymouth, where citizen-science coverage is often thinner than in rural catchments.