Hundreds of properties in East Sussex remain without water or with a limited supply for a sixth day.
Southern Water said 32,500 customers in Hastings and St-Leonards-on-Sea were initially left without water after a pipe burst on Thursday.
The owner of a music venue in Hastings questioned whether the water firm was investing enough to solve the issues.
Southern Water has apologised for the disruption, stating that all affected schools were now able to re-open.
All schools were due to reopen on Tuesday, East Sussex County Council said.
St Paul’s Academy said pupils were allowed to wear non-uniform clothes as parents may not have been able to wash uniforms over the weekend.
At 12:00 BST on Tuesday, Southern Water said supplies had been restored to about 30,000 properties.
However, customers may notice their water is “cloudy”, the firm said.
“Samples have been collected from our water treatment works and customer properties as these are brought back into supply to confirm the water quality meets the regulatory standards,” a spokesman said.
Newgate reservoir has re-opened and pressure is building back to normal after a its temporary closure had led to interruptions, the firm said.
However, up to 2,000 properties in parts of St Helen’s and St Helen’s Wood are unlikely to see supplies return until Tuesday, when the Fairlight Reservoir had been restocked, it says.
A fleet of 24 tankers is also being used to support areas still without supply.
Two bottled water stations – at Asda and Sea Road – re-opened at 08:00 on Tuesday.
A third, at Tesco in Church Wood Drive, has been closed and is to be moved to a “more suitable spot”.
Southern Water said it had distributed more than a million litres of water to customers over the past four days – making it the biggest bottled water operations ever handled by the company.
Paul Mandry, the owner of the music venue The Crypt, said he had been forced to close, and called on Southern Water to invest more into solving the problems.
“I don’t really think they care about the small businesses in Hastings and the affect the floods and now the burst water main is going to have on the town,” he told BBC Radio Sussex.
Over the weekend, East Sussex councillor Godfrey Daniel said: “The impact on the town will be drastic, a lot of people will lose a lot of money.
“These businesses are struggling as it is with the cost-of-living crisis.”
The outage coincided with the annual Jack in the Green Festival in Hastings and the May Day Bike Run, both of which see thousands of visitors.
The events went ahead, but some revellers said they had been filling up buckets with seawater in order to flush toilets.
Keith Leech, chair of trustees for the Jack in the Green event, said: “On a Bank Holiday weekend, that’s absolutely not what the town needs.”
Southern Water apologised for the disruption the outage had caused, “especially over the bank holiday weekend”.
Source: BBC