A MAJOR investigation by the Environment Agency (EA) has revealed Southern Water discharged enormous volumes of sewage into protected coastal waters.

The case, which opened for sentencing on Tuesday, at Canterbury Crown Court, has been described as the worst brought by the EA in its history.

In March, 2020, Southern Water admitted 51 counts of knowingly permitting entry to coastal waters of untreated sewage, and sentencing is imminent.

The EA’s biggest investigation to date has revealed just shy of 7,000 illegal discharges — untreated sewage being dumped into the sea at 17 locations across the South Coast.

The utility company is contesting the level of harm caused by the discharges.

The scope of the investigation comprises five years, from 2010 to 2015.

Sites included the Hampshire and Kent coasts, but discharges were not made from the Isle of Wight.

"In 2014, we noticed real problems with the quality of shellfish, and there wasn't anything that immediately jumped out at us explaining the year-on-year drop in quality," said Andy Turton for the EA.

"We started to find a few problems around Southern Water assets, and our colleagues in Solent and South Downs area reported similar.

"We joined up and started to build a picture of quite a few problems.

"That's where our national enforcement service decided to launch Operation Garden, and formalised the investigation.

"We looked at 16 wastewater treatment works and one combined sewage outfall."

The sites involved include four in Hampshire, of which three are outside Southampton — at Millbrook, Portswood and Marchwood.

In 2019, Southern Water paid £126m in penalties and rebate payments to customers, over serious failures in the operation of its sewage treatment sites.

Ofwat, which regulates the industry, conducted then investigation, and found a lack of investment had led to equipment failures and spills of wastewater into the environment.

A new chief executive was later appointed and Southern Water made substantial changes to its management team.

The sentencing hearing is due to finish today (Friday, July 9).