Carter said Northbridge residents coped without water until supplies were restored at about 7pm last night.
"Our people are the generation that are used to coping, so it was not too much of an issue," he said.
"It caused us problems, obviously, with the large kitchen that we have at the rest home and the cafe and all that sort of thing."
He said lunch had already been prepared for residents when the latest cut occurred this morning.
He said last night's cut also affected The Warehouse and other businesses in The Warehouse Way.
Watercare said water tankers have been dispatched to the site.
An AUT spokesman said mains water to its campus has been rerouted by Watercare and restored just before 1pm.
"We apologise for any inconvenience this incident caused to students."