As many as 12,000 residents in Surrey can expect no or low water pressure on Monday morning, Thames Water has said, as it works to return supplies to normal after Storm Ciaran caused problems at a treatment works.
Improvements have been made at Shalford water treatment works after around 13,500 homes were affected on Sunday in areas such as Guildford and Godalming.
But water will likely only gradually return over the course of Monday, Thames Water warned, adding that bottled water stations will reopen at 9am.
Underground reservoirs "which have run very low" are being refilled, the company said, adding that water has been pumped into the system all night.
The following postcodes are affected: GU1, GU2, GU3, GU5, GU6, GU7 and GU8.
The issues on Monday morning could affect schools and businesses.
Waverley Borough Council leader Paul Follows criticised Thames Water for lack of communication.
He told BBC Breakfast: "Water infrastructure in this country is clearly crumbling.
"I have certainly got questions for the county for not declaring a major incident much earlier, and I will certainly have questions for our MP about the state of water infrastructure in the local area because it is clearly failing.
"People have been quite upset... we've had almost no communications from Thames Water right from the start, so just actually trying to get basic information about what the problem is, how they're resolving it and when it will be resolved, that has actually been the challenge."
People queued for more than an hour on Sunday for water in south west Surrey, where Chancellor Jeremy Hunt is MP, as Surrey County Council (SCC) declared a major incident.
Some reported that bottled water supplies ran out.
One Guilford resident wrote on X, formerly Twitter: "Nearly 48 Hours with no water. The bottled water was out by the time I got anywhere near the front of the queue. I am cleaning my teeth with sparkling water. I am PISSED off."
1/3 heard from Surrey Gold Command and TW CEO that TW hoping to bring Shalford treatment works back on line within next hour having identified the cause now. They have significantly reduced water turbidity and are hopeful that the alarms will not trip once it has gone through .. pic.twitter.com/RAgnbfEe3R
— Jeremy Hunt (@Jeremy_Hunt) November 5, 2023
In its latest update, Thames Water said: "Our engineers have made improvements at Shalford water treatment works, following problems caused by Storm Ciaran.
"However, supplies are likely to only gradually return over the course of Monday. We’re really sorry if you’ve been affected by these issues across GU1, GU2, GU3, GU5, GU6, GU7 and GU8.
"Although the situation is improving, we need to refill underground reservoirs which have run very low.
"We’ll be operating our fleet of tankers through the night, pumping water into the local supply network.
"We’ve closed our bottled water stations but will aim to re-open them at 9am tomorrow, at Artington Park and Ride, Old Portsmouth Rd, Guildford GU3 1LP, and Crown Court Car Park, The Burys, Godalming GU7 1HR.
"Thank you for bearing with us – we know how worrying and inconvenient it is to be without water and are continuing to work to get things back to normal."
On Sunday Thames Water said it was "really sorry about the continuing water supply problems" suffered by people.
After speaking to Alastair Cochran, Thames Water’s interim co-chief executive and chief financial officer, Mr Hunt posted a message on X, formerly Twitter, which said the firm was "resetting and reprogramming" the control system.
The MP added: "If successful they will be able to restore supply to affected customers. Artington now open for water supply so that should relieve congestion.
"Good that SCC have now declared this a major incident. Next question is what the impact will be on schools tomorrow if it is not resolved. Also getting messages from pubs that have lost trade from closing on a busy day – big big impact on many people."
The Chancellor later tweeted that the firm was "tankering water to ensure that they can support hospitals and bottled water stations remain open".
#Guildford We’ve made progress fixing the supply issues but need to refill reservoirs. This means water is likely to only gradually return through tomorrow. We’re providing bottled water till 9pm and expect to do so again tomorrow.
More at https://t.co/5RJvdjEZTw
— Thames Water 💧 (@thameswater) November 5, 2023
By Sunday evening Mr Hunt tweeted that water chiefs were hoping to bring Shalford treatment works back on line as they had identified the cause of the problem.
He added: "They have significantly reduced water turbidity and are hopeful that the alarms will not trip once it has gone through."