Townhouses have been flooded at Elermore Vale, following a burst water main.
Residents in Aries Way received an early wake up, with thousands of litres of water gushing through 12 villas just before 4am.
Everyone managed to get out safely, however the torrent of water has left a huge amount of damage.
Some of the units have been structurally damaged and are uninhabitable.
"The water was more than a foot deep running through houses," Fire and Rescue NSW Insepctor Peter Nies said.