A coach carrying dozens of tourists became trapped in a sinkhole when a water main burst beneath a busy south-east London road.
A major incident was declared by police as Lee High Road flooded near Lewisham on Saturday night.
Some people had to be moved to a temporary shelter while many living in surrounding areas have been left without any water supply.
Thames Water said the repairs were “complicated”.
The coach remains trapped in the sinkhole.
The Met said about 100 tourists, including 30 children, had been left stranded by the flood.
Thames Water said the burst main had affected supplies for people living in large parts of south-east London, including those in SE3, SE10, SE12 and SE13.
Emma Shaw, who lives in Lee Green, said she had been without water “for at least 10 hours”, while her family in Lee Road also had no supplies.
The water company said they had “successfully re-routed the water” but were waiting for the pressure to build up.
Lee High Road remains closed, with police warning it will be shut “for some time”.