Hundreds of people in Kent remain without tap water, as South East Water continues work to restore drinking water supplies.
Supplies have been restored to 15,500 customers, South East Water's incident manager Steve Benton said.
He said the company was "conscious that today is another hot day and demand is therefore remaining high".
"Although our network is recovering, levels of drinking water in our storage tanks are still low and we are asking customers to use water for essential purposes only - drinking, cooking, and hygiene. We are continuing to use our tankers to support the network and aid recovery."
Mr Benton said the company was working to restore supplies to around 500 customers across Kent after drinking water storage tanks in their areas reached a critical area.
The areas affected included Cranbrook, Ulcombe, Mereworth, Kemsing and Wrotham.
He said there are around 3,600 customers who may experience low pressure or intermittent supply during the day. They were in Coxheath, Loose, Headcorn, Ulcombe and Brenenden, and Wraik Hill.
"We are sincerely sorry to customers for disruption to their water supply and know how frustrating it is, especially in hot weather," he added.
"While tap water supplies have returned for most customers who have been impacted across Kent, some may still experience water supply issues as a result of the incredibly high demand during this heatwave."
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The problems have grown significantly since Monday when South East Water said about 250 properties were affected.
The firm said it planned for the hot weather but demand was still outstripping the speed at which it could treat and pump water to customers' homes.
It said 670 million litres had been used across its area on Bank Holiday Monday, 100 million litres more than average.
South East Water boss Dave Hinton quit earlier this month, just a week after its chairman, following demands by MPs for a change of leadership.
Mr Hinton, who had been chief executive since 2020, had previously said he would take no bonus in 2026 following an outage late last year that left tens of thousands without water for two weeks in the Tunbridge Wells area.
A report by the Environment, Food and Rural Affairs Committee said the company was "devoid of proper leadership" and "riddled with cultural problems".
(c) Sky News 2026: Hundreds of South East Water customers in Kent remain without water
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