Southern Water has 'prevented 55 pollution incidents' as it seeks to improve joint-lowest environmental rating

The water company said it is a ‘success story’ that has ‘helped slash incident numbers by 35 per cent in the past year’.

A spokesperson for Southern Water explained: “Harnessing the power of high tech radar sensors beneath more than 20,000 sewer manholes, Southern Water has prevented 55 pollution incidents in two years.

"Southern Water has the UK’s first digital sewer network and the success of the programme means another 10,000 monitors will be added.”

This comes after the Environment Agency (EA) revealed that almost two-thirds of significant pollution incidents in the water and sewerage industry in England last year were from infrastructure managed by the South’s two biggest operators – Southern Water and Thames Water.

Southern Water said it accepts that ‘there is a lot more to do’ after it received the joint-lowest rating across the industry for environmental performances.

John Penicud, director for wastewater Operations at Southern Water, said: “Despite our turnaround plan demonstrating strong progress, the number of serious pollutions is unacceptable, and we accept that there is a lot more to do as we urgently work to achieve a three-star rating.”

In a second blow, the company’s plan for future improvements was categorised as inadequate by the water services regulation authority Ofwat – and Southern Water faces the prospect of a £54million penalty.

As it strives to improve, Alex Saunders – head of wastewater networks at Southern Water – paid tribute the work of the ‘proactive maintenance teams’, which uses the sewer level monitors to ‘detect when fatbergs are starting to form in pipes’.

He added: “On top of the important cut in pollution incidents is the impact on customers – 498 garden floods have been prevented and better yet 48 homes have been spared the misery of internal sewer flooding.”

Southern Water said blockages from fat, oil and grease and ‘unflushables’ such as wet wipes and sanitary products are the biggest cause of pollution incidents – responsible for 28 per cent last year.

A spokesperson added: “Sewer level monitors are radar devices fitted beneath manholes in high risk areas. They constantly measure the level of wastewater flowing beneath them. Machine learning then helps us to understand how flows behave normally – in dry weather, wet weather and in the morning and evening ‘wastewater rush hours’.

“If the level starts to creep up this will be flagged as a sign that a blockage is starting downstream of the monitor. Our proactive teams can be dispatched with heavy water jets and other tools to clear the growing fatberg before it causes a serious problem.

“The monitors are also being used to monitor for high ground water pushing its way into our pipes and helping us prioritise areas at risk of groundwater flooding for work to seal sewers and customers’ pipe against water getting in.”

Meanwhile, Southern Water continues to consider Ofwat’s ‘initial proposals’ for how customer bills and investment plans will look between 2025 and 2030.

The water regulator expressed its view that Southern Water's plan ‘does not meet the minimum expectations’ in the round despite ‘significant intervention’.

Ofwat will apply a financial penalty of £54 million to Southern Water ‘if it does not improve its plan enough’ ahead of the regulator’s final decisions in December 2024.