United Utilities said it could take several days for waterlogged roads in Old Swan to re-open following a burst water main.
The flooding affected two of the busiest roads in the neighbourhood – East Prescot Road and St Oswald's Street.
Pictures show the water gushing through the neighbourhood and in some cases turning the roads into rivers.
Engineers have been on site since the early hours of this morning to try and fix the burst water main, between the Old Swan Junction and the Tesco Superstore.
A section of road is reported to have collapsed near the junction, where a major pipe – understood to be 36 inches in diameter – burst at around 2am today.
No traffic can access the junction and bus routes have been diverted.
A United Utilities spokesperson said: "There has been a burst on a large water main at the junction of East Prescot Road and St Oswald’s Street.
"Our engineers have been on site since the early hours of this morning and we are gradually reducing flows through the pipe so that we can begin repair work.
"We are re-routing water through other parts of the pipe network and, while there may be a reduction in pressure, we do not expect supplies to go off.
"We are also using our water tankers to help maintain water supplies.
"Some customers may notice a little temporary discolouration to their water. This is not unusual after a burst of this size which can stir up some naturally-occurring sediment in the pipes.
"Customers do not need to take any action and they can continue to use the water as normal."
"The junction of East Prescot Road and St Oswald's Street will remain closed until all repair work is finished and the road is reinstated, which could take several days.
"In the meantime there is a diversion."
United Utilities directed customers to its website for more information and the latest updates.