Southern Water is considering building a £20m plant to convert sea water into drinking supplies.
The firm says a desalination facility would ease water shortages.
The company, which provides water across much of Hampshire, is carrying out an environmental impact assessment on the scheme to build a plant in Southampton.
It would produce around four million gallons of water a day for the city and parts of the Isle of Wight during times of low rainfall.
Southern Water says that if it goes ahead the plant should be ready by 2028.