The Ruapehu District Council is now saying another 24 hours will be needed before Ohakune's water network is safely back online.

The council had earlier been confident supply would be restored around 5pm on Monday.

But it says if the pipeline that carries water from its source to the treatment plant is repressurised too quickly, it could fracture, and cause even longer delays.

Water supplies to the central North Island town were turned off after last month's earthquake near Taumarunui likely damaged a major water pipeline. The town's water reservoir is down to 12 percent.

Earlier on Monday morning the district's mayor had said the problem was more serious than originally thought and could not confirm when the town will have water again.

But Ruapehu District Mayor Weston Kirton later told Midday Report that there had been a reassessment of the conditions and water would be back on by 5pm, with experts coming in from all around the country.

Ruapehu Mayor Weston Kirton discusses Ohakune water issues

'Extremely technical and challenging situation'

Earlier on Monday afternoon the council's chief executive Clive Manley said it was still aiming to get water back by 5pm on Monday.

He said at the time service contractor Veolia was able to locate hidden valves and was installing new ones to help release trapped air from the system.

"Restoring the supply has been complicated by sections of the raw water pipeline being buried and located in heavy bush, making valves difficult to find.

"Veolia has developed a plan for recharging the water network that includes introducing water from the treatment plant end of the system."

Additional staff and resources were brought in from Whanganui, Auckland and Central Hawke's Bay to help with the repairs, he said.

However later on Monday afternoon Manley said another 24 hours would be needed and water was expected to be back around 5pm Tuesday.

He said if the pipeline that carried water from its source to the treatment plant was repressurised too quickly, it could fracture, and cause even longer delays.

"A slower, controlled approach is therefore needed to protect the repaired infrastructure and safely restore the town's water supply."

"This has been an extremely technical and challenging situation. We have been working to keep the community fully informed as new information becomes available, but the situation and expected restoration time have continued to evolve as work has progressed."

Council's water services contractor, Veolia, had confirmed that the airlock affecting the raw water pipeline had been resolved.

The council said emergency water supplies were available from Ruapehu District Council's office at 37 Ayr St and people could reuse water bottles at this same location.

It said port-a-loos were located at the council's office; Thames Street opposite the Powderhorn; Goldfinch Street / Shannon Street; and the rear carpark of the Ohakune i-SITE.

"We are contacting schools to let them know about this situation. We expect schools will make the decision to close, but that is their decision to make."

Residents were asked to keep all taps inside their properties turned off while network restorations where ongoing.

Mayor had been unsure when water would be back

Kirton had first told Morning Report it had been more difficult to fix the piping than had been initially thought.

"We've found the leak, we've actually fixed the leak, we've then tried to flush the system out and it's not working that well... and so we're obviously working hard to overcome that problem."

Kirton had said there was about 5km of concrete piping that was about 70 years old and may have been affected by the earthquake.

But it was in difficult-to-access terrain which was hard to flush out, he said.

"As soon as we get on top of the airlocks then we'll be able to manufacture the water and then open the systems up for the town, but it's certainly concerning."

The water had previously been expected to be back on by Monday afternoon, but Kirton told Morning Report that was no longer the case, and he did not want to speculate on when it would be back on.

The water plant was brand new and the issue was actually getting the water to the plant, he said.

The emergency situation was worsening and they would be dealing with that this morning, Kirton said.

"It could well be that we have an emergency situation to actually get water from elsewhere, through tankers or the like."

It would take longer than expected to get the existing plant up and running, he said.

It may be necessary to put an emergency water system in place before Ohakune's regular system can be fixed, he said.

"So I can't speculate whether it's a state of emergency yet, but that's one of the considerations you know whether we call on the government for help to actually overcome the issue with our town."

There was an influx of people in Ohakune at this time of year and there were businesses that wanted to be open and operating, he said.

"So we've got to have a Plan B and we'll take whatever measure it takes to make sure we actually get water to the households."