Southern Water project manager Julie Anne Stokes said: “We know the majority of residents support this scheme so we’re delighted our plans have been approved, in principle.
“We will work with Southampton City Council to produce the required documentation to ensure we can finalise the construction programme and start on site as soon as possible, working to the requirements set down by the Council.
“The end result will be a modern treatment works to serve Woolston long into the future.”
The scheme will happen in phases. The first phase, due to start in the spring, will be to build a temporary works to treat wastewater before elements of the existing site are demolished.