Homes and businesses in Bearsden and parts of Milngavie lost their water supply following a massive mains burst.
People woke to find their taps running empty - and some households have had to deal with the heartache of flooding.
Maryhill Road near Canniesburn Toll has been closed - and is likely to remain so for some time, causing major travel disruption over the next few days.
Scottish Water said teams are now working to restore the service.
The burst occurred shortly after 5am on Maryhill Road near its junction with Coronation Way, just south of Canniesburn Toll.
More than 23,000 properties in Bearsden, Maryhill and some parts of Milngavie areas have been affected.
By 5pm on Monday, 18,000 had been reconnected.
Those still without water are mainly in the Switchback Road area of Bearsden, the Summerston area and a small number in Kelvindale.
A spokesman said: “A large 36 inch burst water main has been located at Maryhill Road affecting a widespread area.
“Engineers are working on re-zoning the network and bringing in water supplies from other areas.
“We will work to restore supplies to other affected customers as soon as possible.
“The road has been closed following the burst. It is anticipated that the repair to the water main and the reinstatement of the road might take some time to complete.
“This is likely to mean there will be implications for road traffic in the area near the burst for some time.
“We are liaising with other relevant agencies and we are grateful for their assistance.
“Customers are advised that when normal supplies are restored they might experience some discolouration in their water and should run the cold tap in their kitchen until their water runs clear.
“Scottish Water apologises for the inconvenience to affected customers, particularly those who have been affected by flooding, and road-users.”
Scottish Water is making bottled water available to customers whose normal water supplies are still affected following the burst main.
To help minimise inconvenience, the utility are making bottles available for customers to collect at John Paul Academy in Arrochar Street, Summerston, Glasgow G23 5LY and at Lochgilp Street, Maryhill, Glasgow G20 ODR.
A location for affected customers to collect bottled water in Bearsden is being identified and will be detailed at www.scottishwater.co.uk as soon as it is operational.
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