More homeowners in Sussex have had water supplies cut off or restricted after at least 300 householders had been without tap water since Friday.
South East Water said supplies were restored overnight to the areas of West Sussex which had been without water for five days.
But the company said some customers in East Sussex were “waking up to low pressure or no water” on Wednesday.
The water supplier said it was setting up bottled water stations.
The latest problems are hitting customers in Rotherfield, Crowborough, Mayfield, Hadlow Down and Five Ashes, as well as some in Heathfield.
Gary Walker, from Warninglid, said he had been forced to “manually remove waste from the toilet and bury it in the garden”.
Di Holwood, from Bolnore near Haywards Heath, said it had been “horrendous” living without water since Friday, but her supply had returned at about 02:00 BST.
“I have no confidence this water is going to stay on for more than a few hours.”
Customers in Haywards Heath, Cuckfield, Warninglid, Slaugham and Bolney in West Sussex have seen water supplies return overnight.
Steve Andrews, head of central operations for South East Water, apologised and said: “Supplies have been restored overnight and we are more hopeful we will be able to maintain those supplies throughout the day.
“We are continuing to ask customers to only use water for essential use.”
He said more than 150 million litres of extra water were being pumped into the network as the UK heatwave continues.