Watercare is pumping water from tankers into water pipes for almost 600 elderly people in two retirement villages and a hospital affected by a general water outage in the Albany area.
The company has stationed tankers at both the Fairview and Settlers villages since about 8.15am today.
Terry Middlemost, chief executive of Premier Lifestyle Villages which owns both villages, said the tankers were pumping water in so that residents could still get water out of their taps, although with reduced water pressure.
Each village has about 270 residents living independently, and the Fairview village also has 47 hospital patients.
"Watercare has been amazing," Mr Middlemost said. "They phoned us, they knew that we were susceptible with elderly people. They were there first thing this morning.
"We have a reticulated system off the main line. They have hooked a water tanker into that line so water is coming out of their taps and the residents can flush their toilets, but we are limiting the amount of water they can use."
Albany Senior High School has also remained open today after a Watercare tanker filled up the school's tank just after 9am. However Oteha Valley Primary School has an answerphone message saying it is closed due to the lack of water.
Scentre Group, owners of the Westfield Albany mall, said the mall would stay closed for the rest of today, although the New World supermarket remained open.
"We anticipate that WaterCare can restore services to enable us to have the centre with our retailers up and running for trade Saturday 14 March at 9am," a spokeswoman said.
"It is too early for us to comment on compensation or the financial implications of this failure. Our focus remains on getting our retailers to a position where they can recommence trade."
Albany Primary School, Pinehill School and Pinehurst School said their water supplies had not been affected.
North Harbour Business Association, which represents businesses in nearby Rosedale Rd, said it had not had any calls from members so believed they were just outside the affected area.