Water bills for Southern Water customers will fall by eight per cent before inflation is added, a better figure than the national average.
This would see the average water and wastewater bill fall in real terms by £34 from £437 to £403 between 2015 and 2020.
However households could still see the amount they pay rise as water companies are allowed to add on inflation as measured by the Retail Price Index (RPI).
The figures were announced last week as water regulator Ofwat published its determinations on water companies’ business plans.
Matthew Wright, chief executive at Southern Water, said: “Our plan is based on discussions with more than 30,000 customers and local representatives over the course of the last two years and includes 26 clear promises about what we will achieve.
“It will see us deliver better water and wastewater services to 4.5 million people across Kent, Sussex, Hampshire and the Isle of Wight at an average daily cost per household of just over £1.”
Jonson Cox, chairman of Ofwat, added: “This is an important step in maintaining customers’ trust and confidence in the water sector.
“We set out to deliver a challenging but fair outcome. We are requiring companies to meet higher service standards and deliver on their promises to customers.
“We are bringing down bills so customers can expect value for money, while investors can earn a fair return. Companies will need to stretch themselves to deliver much more with the same level of funding as in previous years. We will achieve more resilient infrastructure and better service as a result.”
Tony Smith, chief executive of the Consumer Council for Water, said: “This is good news and a victory for most water customers whose views have shaped water pricing more than ever before.”