Ohakune residents face at least another 24 hours without water after Ruapehu District Council warned repressurising a pipeline damaged in last month's Taumarunui earthquake too quickly could fracture it again.
The magnitude 5.9 quake in July caused a major break in the underground raw water pipeline supplying Ohakune's water treatment plant. The council said because the pipe was buried, the break took time to become apparent and had been difficult to repair.
The council had earlier been confident that water would be restored to the town of 1300 people by 5pm on Monday, but technical analysis found taking the raw water pipeline from no flow to full flow too fast risked fracturing the line.
"A slower, controlled approach is therefore needed to protect the repaired infrastructure and safely restore the town’s water supply."
Water is now expected to return by about 5pm on Tuesday.
The council's water services contractor, Veolia, confirmed an airlock affecting the raw water pipeline had been resolved, but said a slower, controlled approach was needed to bring the network back safely. Additional water tankers have been brought in to speed up the process.
Pipeline through mountainous terrain
Ruapehu District mayor Weston Kirton said the 5km pipeline ran through mountainous terrain near Mt Ruapehu and the council would investigate the full extent of the damage.
"We understand that it could well be damaged through the earthquake that we had recently," Kirton said.
"We'll be having an investigation as to what happened and what things we can put in place to make sure that doesn't happen again."
The outage struck during a busy winter weekend, with hundreds of visitors in the area for snow activities. About 5700 containers of water had been distributed alongside tankers stationed in the town.
Kirton said some residents were frustrated.
"Some people are quite angry at the fact that it's happened at this time. It always happens on a weekend, of course," he said.
"But the people I've been seeing over the last 24 hours, very cooperative. They've taken water in good faith."
Water treatment plant had $10m upgrade
The treatment plant itself was not the problem. Kirton said it had been upgraded last year at a cost of about $10 million and was fully operational.
Some businesses had shut voluntarily over concerns about water that may not have been treated or chlorinated.
The council said the situation had been "extremely technical and challenging" and that expected restoration times had continued to shift as work progressed.
"We thank everyone for their patience, understanding and cooperation while we work to restore the water supply safely and avoid any further delays," the council said.
Emergency water supplies remain available from the Ruapehu District Council office at 37 Ayr St, where people could also return and refill water bottles.
Portable toilets have been set up at the council office, Thames St opposite the Powderhorn, Goldfinch St and Shannon St, and the rear carpark of the Ohakune i-SITE.
The council said schools were beingn contacted about the outage and expected some may choose to close, although that decision rested with individual schools.
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