Streets in the city centre were flooded yesterday as water gushed out on to a stretch of St Vincent Street, spilling out on to West Nile Street and Renfield Street.
As reported in later editions of last night's Evening Times, the leaking Scottish Water works are part of an upgrade to the network of pipes.
Last night, firms and homes faced more disruption as their water supplies were cut off while staff worked overnight in a bid to try and fix a faulty valve.
A Scottish Water spokesman said the fault was difficult to repair because of the pressure on the main.
But business owners fear the water may damage their premises and that it is costing them customers. Several bars, shops and restaurants in West Nile Street have been affected by the burst pipe.
Craig Thomson, boss of clothing shop Fat Buddha Store, in West Nile Street, said: "I noticed it on Friday and called Scottish Water. I was told someone would come out.
"We're worried the water could come into the shop.
"I've seen tourists taking photos of the water gushing out and there are fewer people walking past our shop because there's water everywhere."
Part of St Vincent Street, between its junction with West Nile Street and Renfield Street, has been closed for parking while the work continues.
Linda Brown, of Fired Earth Interiors in St Vincent Street, said: "It is a real worry for us.
"Scottish Water closed the other side of the road while they do the works but that's where our customers normally park so they could carry heavy tiles or furniture a short distance to their cars.
"People are being put off from walking near the shop as we're almost surrounded by water."
Pam Hunt, 57, of Shawlands works at a solicitors' office in St Vincent Street. She said: "My colleagues and I are disgusted about the massive amount of water gushing down St Vincent Street and Renfield Street.
"This has been since last Friday and nothing, as far as we can see, has been done to stop it.
"The water outside the Drum & Monkey pub on the corner of St Vincent Street and Renfield Street is bubbling up about a foot high.
"People are having to walk into the road. I have seen at least two people almost hit by traffic."
A Scottish Water spokesman said repairs were due to be done early today and that some properties in Trongate would be without a supply for a while.
He added: "We apologise for any inconvenience while essential repairs are done."