The company, which provides drinking water to households in Southampton and Hampshire as well as Kent, Sussex and the Isle of Wight, plans to import up to 45 million litres of water a day.
The regional monopoly, which is one of the biggest UK water firms, is in early-stage talks with the Extreme Drought Resilience Service, a private UK company that supplies water by sea tanker, according to the Financial Times (FT).
Tim McMahon, Southern Water’s managing director for water, said importing supplies would be a “last-resort contingency measure” in the event of an extreme drought in the early 2030s.
It comes as most of the company’s supplies are currently abstracted from groundwater and globally rare chalk streams.
The Environment Agency has warned that overreliance on these sources can cause environmental damage, increasing the risk of droughts even further.
The regulator has ordered the company to make dramatic reductions by 2030, although Southern has recently admitted it may need to keep taking water from the rivers until as late as 2035 due to delays in shifting to new water sources.
Southern plans to pay for the shipped water from customers’ bills, the FT reported, adding that imports tend to be expensive because of weight and the additional processing required.
Mr McMahon said the possibility that it would need to import water is “very remote”.
Mr McMahon said: “Importing water would be a last resort contingency measure that would only be used for a short period in the event of an extreme drought emergency in the early 2030s – something considerably worse than the drought of 1976.
“We’re committed to continuing to work with our regulators on developing the right solutions to meet the challenge of water scarcity, while protecting the environment.”
According to water regulator Ofwat, currently around a fifth of water running through pipes is lost to leakage.
Droughts are becoming more frequent and parts of England came close to running out of water in 2022 during one of the driest summers on record.
Southern Water’s situation is particularly acute, with the firm saying it would face a shortfall of 166mn litres a day in Hampshire during a drought.