Detecting a burst rising main in Southern Water’s wastewater network

Southern Water provides wastewater services across the South East of England and runs one of the UK's largest SAM4 deployments. It also helped develop SAM4's burst rising main detection by sharing data from verified bursts recorded since 2024.

Boldre Bridge is a two-pump wastewater pumping station, monitored by SAM4 from the motor control cabinet. Its rising main is 501 metres of cast iron and discharges straight into the receiving treatment works. Nothing on the pipe itself is instrumented. Because the pumps pressurise the main, any loss of pipe integrity changes how hard they have to work, and that change shows up in the electrical data at the cabinet.

At 21:37 on 28 September, SAM4 flagged a change on both pumps at the same moment. Because the two pumps share one main, a leak shows on both together: each pump works harder and empties the wet well faster. A fault at the station would not behave that way.

A Samotics monitoring analyst reviewed the finding and, at 23:50, published it to Southern Water as a burst rising main, with guidance to look for pollution along the route of the main.

Southern Water raised a P1 work order at 00:52. The crew found the station operating normally, so they walked the main and found water welling up in a field. At 02:21 the burst was confirmed, and an on-the-spot ammonia test showed it was sewage. The pumps were switched off and tankers brought in while the repair was scoped. SAM4's indicators returned to healthy on 9 October, when the repaired main came back into service.

• £246k cost avoided
• 1 hour from alert to P1 work order
• 2.5 hours from alert to confirmed burst

"Rising mains are among the hardest assets in the network to monitor. They are buried and rarely instrumented, meaning a burst is often only discovered once it reaches the surface. In this case, the Samotics alert provided our first indication that something was wrong. Acting on the alert, we raised a priority investigation and confirmed the burst within hours, enabling us to isolate the main, deploy mitigation measures and significantly reduce the environmental impact."

Austin Phillips, Programme Manager, Pollution Task Force, Southern Water

Download the detection snapshot (PDF)