Southern Water says a potential sewage spill into a precious New Forest stream was prevented by Artificial Intelligence and one of the 34,000 sewer level monitors installed across waste network.

The Lymington runs for 13.5 miles through Hampshire supporting rich wildlife including the iconic wild ponies, deer and rare birds before draining into the Solent – also a sensitive water body.

Blocked sewers are the single biggest cause of pollution incidents – from manholes spilling into streams to gardens filling with sewage. The very worst kind is internal flooding where sewers back up and pour into sinks, showers and loos.

Thanks to an extensive network of sewer lever monitors, Southern Water teams can now constantly check on flows and spot anything out of the ordinary which might suggest a blockage.

In this case, as the blockage formed, sensors alerted the control room and a team quickly arrived to jet the sewer. They found that wet wipes and other unflushables were causing the problem Unchecked, the sewer would have overflowed from a manhole and into the Lymington, threatening water quality and the biodiversity that relied on the river.

Daniel McElhinney, Proactive Operations Control Manager at Southern Water, said:

“Our sensors measure the level of sewage flowing under manholes in blockage hotspots, but the real innovation is how machine learning or artificial intelligence learns the normal behaviour of sewers and can tell the difference between morning and evening rushes, rain in the system and a blockage forming.

“Instead of turning up after the event to clean up and commiserate with devastated customers we’re spotting hundreds of potential blockages before it’s too late so our teams can prevent pollution by using high pressure water jets to clear the sewer.”

Most customers do not realise the average suburban sewer is only the diameter of an orange or a tennis ball. It doesn’t take much cooking fat to combine with other ‘unflushables’ including wet wipes or even ear cleaning sticks, to form a fatberg.

The system has led to more than 4000 interventions by the water company's teams in the past year.

Around 1 billion wet wipes are removed from Southern Water’s sewer network each year in the South East. While a ban on wipes containing plastic comes into force in Spring 2027, Southern Water is warning that so called ‘flushable’ wipes could create just as big an issue and can still cause blockages.