South West Water’s investment in cutting-edge, real-time monitoring technology is transforming how storm overflows are managed – reducing spills, enabling faster responses, and protecting the environment.
Event Duration Monitors (EDMs), which record data at least every 15 minutes, with some sites capturing updates every two minutes and others as frequently as every 10 seconds, are now installed in 100% of South West Water’s 1,342 storm overflows thanks to consistent investment. Teams at South West Water have a comprehensive, up-to-date picture of the network thanks to this high-frequency monitoring. It enables them to take quicker, more intelligent action to stop environmental damage throughout the region by detecting rising flows, obstructions, or debris early.
Real-time monitoring was crucial in helping South West Water, one of just five businesses in the industry, reduce spills compared to 2023, even though 2024 was the wettest hydrological year on record and saw record-breaking rainfall. Over the past five years, South West Water has cut beach spills during the bathing season by 20%, and they are still taking steps to address customer concerns. Additionally, ¾ of the 2023 top 20 spillage locations have been eliminated by the corporation.
The second-best reliability percentage in the industry, 93.8%, is achieved by South West Water’s EDMs. Many of South West Water’s monitors capture data every two minutes, which provides a far sharper, more immediate image of overflow activity than the minimum 15-minute intervals for EDMs. In addition to being able to react in real time to shorter, faster-moving incidents, this more regular monitoring enables South West Water to make more informed long-term investment decisions based on richer, more trustworthy data.
How data can drive investment
At Duloe, one of South West Water’s highest-resolution monitoring locations, real-time data is driving tangible change. Duloe, close to Liskeard in Cornwall, had one of England’s highest spilling storm overflows in 2023. The site frequently failed to control incoming flows during periods of severe rainfall due to limited storage and treatment capacity. EDMs in this case collect data at 10-second intervals, which is far more frequent than the industry norm of 15 minutes. Short, frequent spills that would have likely gone unnoticed with regular monitoring were revealed by this high-frequency monitoring, which gave a far more detailed view of network activity.
With this knowledge, South West Water was able to identify the issue and make investments right where they were needed, putting in a new 30,000-liter balancing tank and upgrading the storm weir at the local treatment plant with a cloth filter. Spills have decreased in Duloe as a result, and broader monitoring indicates a notable improvement in overall performance. This demonstrates unequivocally that high-frequency data not only shows more, but also facilitates faster and more intelligent investment where it counts most.
An investment programme powered by data
The insight provided by South West Water’s real-time monitoring network is the foundation of its £760 million storm overflow investment programme – the largest in the company’s history. Over the next five years, this data-driven programme will deliver:
Upgrades at high-priority sites targeting overflows that spill most often or affect sensitive areas like bathing waters and habitats. Investments include increased sewer capacity, upgraded pumping systems, and intelligent flow controls.
Expand storage across the network building new storm tanks and detention basins to hold back excess water during heavy rain, reducing pressure on the system.
Nature-based solutions South West Water will work with the landscape to slow surface water before it enters sewers, through sustainable drainage, wetlands and catchment management.
Smarter, more automated operations using live data, sensors and predictive tools to manage flows dynamically in response to weather and network conditions.
Every part of South West Water’s investment programme is underpinned by real-time data, ensuring the investment goes where it will have the greatest impact.
CEO Susan Davy said: “ Real-time data is transforming how we care for our environment. By seeing what’s happening in our network every few seconds, we can act faster, plan smarter, and invest where it matters most. Even in the face of record rainfall, this technology has helped us reduce spills and protect bathing waters — and it’s only the beginning. Our £760 million investment programme, driven by this data, will help us deliver cleaner rivers and seas for the South West, a decade ahead of national targets.”
This technology is a key part of South West Water’s plan to meet the Government’s storm overflow targets a decade early, delivering cleaner rivers, healthier seas, and a better future for the South West.
Source : South West Water
