Exeter’s water network faces upgrade: South West Water launches phase two of groundwater risk mapping

An innovative project to identify areas most at risk of groundwater infiltration in the South West has entered its second phase, aiming to make Exeter and surrounding communities’ sewer networks more resilient to climate change and ageing infrastructure.

The Groundwater Infiltration Risk Mapping Project is a partnership between South West Water and the University of Exeter’s Centre for Resilience in Environment, Water and Waste (CREWW). 

It uses advanced geospatial technology, modelling, and data analysis to pinpoint where water seeps into sewer systems through cracks, joints, or damaged connections. 

This process can increase the volume of water needing treatment, raise carbon emissions, and heighten the risk of flooding and pollution.

Phase one, completed in October 2024, focused on the Lower Otter catchment. 

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The team produced detailed risk maps highlighting zones that required urgent maintenance, areas needing monitoring, and sections with low infiltration risk. 

These maps are already helping South West Water target maintenance more efficiently.

Following the pilot’s success, phase two is now underway and will cover larger catchments in Dawlish and Camborne, with completion expected in October 2026. 

The project will expand the mapping and modelling framework, providing data to inform sewer network maintenance, drinking water protection, and long-term infrastructure planning across the region.

Mark Jacob, Senior Asset Manager at South West Water, said: “Groundwater infiltration can be hard to see, but it can have a real impact on how our sewer networks perform.” 

“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.”

University of Exeter Postdoctoral Research Fellow Nejat Zeydalinejad added: “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.”

“These outputs support more targeted, efficient, and climate-resilient decision-making. We hope Phase 2 progress will lead to Phase 3, where this expertise could be applied across the region’s entire sewer system.”

The project is fully funded by South West Water, with phases one and two costing around £400,000 in total. 

The company has invested £10 million in CREWW since 2021 to equip the centre with cutting-edge laboratory facilities for water sector research, as part of a wider £21 million commitment.

For Exeter residents, the project could bring tangible benefits. 

Reducing groundwater infiltration helps prevent sewer overflows during heavy rainfall, which can lead to localised flooding and pollution. It also protects water quality in rivers and streams across the city and surrounding areas. 

Local homeowner Sarah Williams said: “Anything that helps prevent flooding near my home is welcome. It’s reassuring to know South West Water is using science to be proactive, not just reacting after the fact.”

South West Water emphasises that while the model is being developed with operational input, it is not yet fully validated and is not in active use on the network. 

Potential Phase 3 expansion is expected to be reviewed in early summer 2026.

Mark added: “With around 25,000km of sewers across the region, developing a faster way to identify areas most at risk will help us target fixes more effectively, free up capacity, and improve resilience in catchments that experience high infiltration.” 

“This isn’t just about pipes, it’s about protecting communities like Exeter and making our water systems ready for the challenges of the future.”

The project is part of South West Water’s wider programme to assess and improve the resilience and sustainability of Exeter’s water and wastewater infrastructure.