Hundreds of households across Kent and East Sussex were left without water after supply outages linked to soaring demand during the hot weather.
South East Water said increased water usage during the heatwave had placed major pressure on its network, particularly in higher ground areas.
The disruption began on Saturday and worsened on Sunday, when around 800 properties in the Kent villages of Charing, Challock and Molash experienced low water pressure or complete supply loss.
A further 168 homes in Eastbourne were also affected by outages, while at least 250 properties remained without water on Monday.
South East Water blamed the problems on rising demand caused by the warm weather.
“As a result of the recent hot weather, we’re seeing increased demand across our network and we’re having to pump far more drinking water than usual,” the company said.
The supplier also urged customers to reduce heavy water usage during peak periods.
“Sun’s out. We know the drill: nobody wants a water company telling them to save water when there’s leaks. Fair point,” the company wrote on social media.
“Our reservoirs are healthy. There is no shortage of water. But if we all use hoses at Saturday lunchtime, the water pressure drops and homes at the top of the hill can run dry.”
The outages come just weeks after MPs accused South East Water of incompetence over repeated supply failures affecting thousands of customers.
The company is currently facing a possible £22 million fine from regulator Ofwat over long-running disruptions to water services.
Following criticism from MPs, South East Water chief executive David Hinton announced plans to step down, while the company’s chair also resigned.
Steve Benton apologised to affected customers and confirmed technical problems at a pumping station had worsened the crisis.
“We are sorry to our customers in parts of Kent who have experienced low pressure or no water intermittently this weekend,” he said.
“This follows a technical failure at our pumping station near Charing, which means we have struggled to push water to properties on higher ground.”
The company reopened a bottled water station at Challock village hall and arranged deliveries for vulnerable residents unable to travel.
Separate overnight supply issues also affected dozens of homes in Whitstable after faults with booster pumps.
The disruption comes as experts warn Britain must urgently reduce water consumption to avoid severe shortages in the coming decades.
The UK currently has one of the highest daily household water usage rates in Europe, averaging between 142 and 150 litres per person each day.