A water expert says Aucklanders should try to flush the toilet only once a day for the next week or two until the city's water crisis eases.

Water NZ chief executive John Pfahlert said it could take "perhaps a week" or "a week or two" for the sediment to settle in the main water treatment plants fed from the waterlogged Hunua Ranges.

He said Watercare's water savings target of one-eighth of normal consumption, a cut of 20 litres per person per day off the normal 160 litres per person, was "achievable" in the short term.

Aucklanders face largest water crisis in 23 years


"It's more of a challenge the longer it goes on," he said.

But he said it would require some serious lifestyle changes especially with showers and toilets, which together took "the lion's share" of household water.

"A lot of people have 10-minute showers," he said.

"If you limit yourself to a quick two minutes, and perhaps only flush the toilet once a day, you can do it.

"It's an emergency situation. It's a heck of a lot easier to do that than everyone having to boil water in a pot on the stove."

Pfahlert said Auckland already used less water per person than any other part of the country because it was one of the first cities to introduce water metering.

Cities such as Invercargill, where water is free and unmetered, use 400 litres per person per day.

He said water usage was less in wet weather anyway because people did not need to water their gardens and were less likely to wash their cars.


"So there is a possibility that in the short term people could save another eighth without much difficulty," he said.

"It requires people to have shorter showers, not flush the toilet as often, and not leave the tap running when they are cleaning their teeth, It's lot of small things like that."