South West Water has moved into the second phase of an innovative project designed to map and predict areas most at risk of groundwater infiltration across the South West, following the successful completion of a pilot study.
Delivered in partnership with the University of Exeter through the Centre for Resilience in Environment, Water and Waste (CREWW), the Groundwater Infiltration Risk Mapping Project aims to strengthen the resilience of water and wastewater systems in the face of climate change and ageing infrastructure.
Across England and Wales, hundreds of thousands of kilometres of sewer networks are more than a century old. As these assets age, they become increasingly vulnerable to cracks, damaged joints and failing connections, allowing groundwater to seep into the sewer system.
Groundwater infiltration increases the volume of water requiring treatment, placing additional pressure on sewer networks, raising treatment costs and carbon emissions, and increasing the risk of flooding and environmental pollution.
Targeting risk before problems occur
South West Water’s project uses geospatial technology, data-driven mapping and groundwater modelling to identify where infiltration poses the greatest operational risk. By understanding where problems are most likely to arise, the company aims to intervene earlier and target maintenance more effectively.
Phase 1 of the project was completed in October 2024 and focused on the Lower Otter catchment. During the pilot, the project team developed a new methodology to map and predict infiltration risk across the sewer network.
The resulting risk maps highlighted areas requiring urgent attention, locations needing close monitoring, and zones where infiltration risk was low. This enabled operational teams to prioritise resources and address issues before failures occurred.
Expansion to larger catchments
The success of the pilot has led directly to Phase 2, which is now underway and will continue until October 2026. This phase will apply the methodology to two larger catchments in Dawlish and Camborne, creating a more comprehensive set of models that can be used more widely across the region.
The expanded dataset will support not only sewer network maintenance, but also longer-term planning around drinking water resources, groundwater pollution prevention and infrastructure investment.
Mark Jacob, Senior Asset Manager at South West Water, said the work would enable more informed and proactive decision-making.
“Groundwater infiltration can be hard to see, but it can have a real impact on how our sewer networks perform,” he said. “By combining local knowledge with new data and modelling techniques, we can make better decisions about where and when to intervene. This helps reduce the risk of pollution, lowers carbon emissions, and keeps costs down for customers.”
Science-led resilience planning
The project forms part of South West Water’s wider commitment to science-led, data-driven approaches delivered through CREWW to improve environmental outcomes and long-term resilience.
Nejat Zeydalinejad, Postdoctoral Research Fellow at the University of Exeter, said the project is already demonstrating global relevance.
“The Groundwater Infiltration Risk Mapping Project is delivering cutting-edge geospatial and physics-based models to produce high-resolution hotspot maps for sewer networks across the South West,” he said.
“These outputs support more targeted, efficient and climate-resilient decision-making. The global significance of this work is already clear, with four Q1 journal publications to date, including two in Water Research.”
He added that the team hopes the project will progress to a third phase, enabling the approach to be applied across the entire South West sewer system and supporting a more resilient and sustainable wastewater infrastructure in a changing climate.
