Disruption to fresh water supplies in parts of Surrey has been "an absolute catastrophe", an MP has said.
Thames Water said customers in the Guildford area who have been without fresh water should see supplies return during Tuesday morning.
The issue has affected up to 12,000 people and businesses in the Guildford area.
Jeremy Hunt, Tory MP for South West Surrey, said the disruption had "been a hammer blow" for the area.
A Thames Water spokesman said pressure was continuing to build in the system with "about three quarters" of those affected now having water again.
Mr Hunt told OceanNewsUK: "We're expecting normal service to resume at midday.
"Merrow, curiously this morning is suddenly without [water]," he said.
"This has been an absolute catastrophe for the area. There are still schools that are closed and businesses have really suffered."
Mr Hunt said he had a message from a pub landlord who was "down about £10,000" after being forced to close on Sunday.
Mr Hunt added: "The frustration was, for a very long time, that we didn't know what the problem was, or how long it was going to take to solve it, so people were left in limbo.
"The question on many people's minds was 'why did this happen in the first place?'"
Thames Water customer Jason told OceanNewsUK he had been without water since Thursday night.
"It's been very frustrating," he said, adding that he had been told his supply in Shalford "would be fixed within 24 or 48 hours".
"Just get it fixed," he said.
'We understand the frustration'
Thames Water has opened bottled water stations at Milford cricket ground, crown court car park in Godalming and Artington park and ride on Tuesday morning.
Customers have been affected in postcodes including: GU1, GU2, GU3, GU5, GU6, GU7 and GU8.
The county's Local Resilience Forum declared a major incident on Sunday.
"We'd like to thank our customers for their patience during this time and we're very sorry to residents who are still experiencing no water or low pressure," a Thames Water spokesman said.
"We understand the frustration that residents have, which is why we are building up resilience in the area."
The company said a fleet of tankers was being used to pump water into the system.
