The proposed rise would be the highest across the country.
This comes less than two weeks after watchdog Ofwat imposed penalties on the company for missing key targets which forced the company to slash customer bills in 2025-26.
Ofwat said Southern Water’s share of the £157.6 million penalty it issued to water companies across the country is £31.9 million.
The company failed in its commitment to reduce pollution incidents by 30 per cent. Across the board, these were reduced by only two per cent.
Ofwat said Southern Water’s share of the penalty £157.6 million penalty is £31.9 million Now, water companies have asked Ofwat to approve an increase which is higher than they originally requested earlier this year.
They initially asked Ofwat if they could increase bills to an average of £585 by 2030 – an increase of about one-third from the current average of £439.
The watchdog pared back those requests to an average of £535, in its draft price review in July.
While Souther Water bills would rise by 84%, the latest requests by water firms would see the average consumer bill in England and Wales rise by 40% between now and 2030, costing £615 per year.
Stuart Ledger, Southern Water’s chief financial officer, said: “We understand that in percentage terms, our proposed bill rise is among the highest, and that this may cause concern among some of our customers, but we are taking this approach in response to what our communities have told us they want us to deliver.
“We are ready to invest to deliver huge environmental benefits and a secure, resilient water future for the region and look forward to working with our regulators to achieve this.”
Ofwat is due to make a final decision on bill increases on December 19, with companies going to the negotiating table with regulators before then.