Blow-up bags help Thames Water reduce sewer flooding

New blow-up bags which temporarily block the flow of wastewater in sewers so they can be safely inspected are helping Thames Water reduce flooding.

The inflatable devices are being used alongside high-tech equipment and can seal off sections of pipe up to 90 metres long so extendable cameras cable can be used to search for any blockages, holes, cracks or other defects.

Thames Water is the only water company to use the devices, made by Scottish company Sarco Stopper, in its sewers.

With no sewage passing through the pipe, engineers can also determine if any liquid picked up by the cameras has leaked into the sewer from an outside watercourse such as a river or stream.

Any issues can then be fixed before they cause problems for the environment or customers, such as flooding if the network becomes overloaded during heavy rainfall.

Tankers are on hand to pump out any excess waste should the flow upstream get too high, ensuring customers’ homes and gardens aren’t at risk.

Jonathon Maw, Thames Water’s network manager, said: “This equipment is ground-breaking for us as without it the sewers would be full of wastewater, making it much harder to detect any points where water could be leaking in from outside or blockages.

“If we can quickly and easily spot these problems, we can make sure we get them repaired. While the weather is drier and hotter, we’re using the devices to inspect as much of the sewer network as possible and fix any issues ahead of the wetter winter months.”

The devices are just part of a range of equipment Thames Water is using to reduce sewer flooding, along with other tools such as transportable flood monitors and even sonar.

Orca uses soundwaves to analyse the inside of sewer pipes and then report back on any issues using a traffic light system, with green indicating a healthy sewer, amber that a problem may need further investigation and red showing that the pipe is defective.

Operated by just one engineer, the system has been used to diagnose up to 5.5km of pipe a day, more than five times what a crew of two was previously able to manage with camera surveys.

More than 700 flood monitors have also been installed in sewers, detecting hundreds of blockages. The devices, which can be fixed in manholes in just 15 minutes, are triggered if water levels rise too much.

They have already been used in flooding hotspots and during large events such as Royal Ascot and Wimbledon and there are plans to install thousands more.

As well as helping to fix pipes, the data gathered by these tools is fed into a virtual map of the 108,000km sewer network in the region, which helps predict blockage hotspots and speed up the response time.

In the last year, Thames Water engineers cleaned more than 900km of sewers, a 50 percent increase on the previous year’s total and three times higher than in 2017/18.