Taps could be turned off in homes across Auckland under drastic measures being drawn up in case the city's prolonged drought turns into a major crisis over summer.
Auckland Mayor Phil Goff says without enough rain in winter and spring, the city's water supply will plummet to 200 million litres of water a day at the height of summer when usage peaks at 600 million litres a day.
Since May 16, outdoor water restrictions across the city have set water usage targets for 410 million litres a day or less. Aucklanders have also been encouraged to limit showers to four minutes.
The dams were 44.8 per cent full yesterday when normally they would be 78.4 per cent full.
Goff said planning has started for a worst case scenario, which includes options for turning off water for part of the day and reducing water pressure to a trickle in homes, which use 70 per cent of the city's dwindling water supply.
Businesses would also face disruption in the post-Covid economic recovery phase "which we desperately want to avoid", he said.
The shortage of water in Auckland's nine dams is due to a significant lack of rain, including 78 days with less than 1mm of rain from January 20 to April 6. The region has recorded less than half of its normal rainfall since November last year.
This week, Watercare invoked emergency power to take an extra 15 million litres of water a day from the Waikato River to increase production from the river to 165 million litres a day and reduce demand on the region's drought-hit dams.
The council-owned water company has brought a dam in Papakura and a bore in Pukekohe back into service that will add 11 million litres of water a day.
Watercare is also negotiating with Hamilton City Council to use 25 million litres a day of the council's allocation on a temporary basis, and has had a resource consent application before the Waikato Regional Council since 2013 to take a further 200 million litres of water a day.
Watercare chief executive Raveen Jaduram said the situation was becoming critical.
"This week we received a seasonal weather forecast suggesting the rest of winter and spring will be drier than normal," said Jaduram, adding that as well as Watercare increasing water sources, Aucklanders need to do their bit and reduce their water use by at least 20 litres a day per person.
Goff said the use of emergency power highlighted the urgency of the situation and the need to explore every single source of water supply to head off the crisis. He too urged people to reduce water usage.
The mayor had some stern words for Watercare, saying it provided high quality water and wastewater but had not planned adequately for exceptional weather conditions and severe drought.
"That is what we are facing at the moment. I think this is a wake-up call for them," he said.
Goff also wants Watercare to consider temporary or long-term desalination, recycling of wastewater and making it easier for people to install water tanks in urban areas.
He said a report is coming from council strategy chief Megan Tyler to look at scrapping resource consents for water tanks and providing incentives for people to use rainwater to water the garden, wash the house and car, and feed through the toilet system.
Rainwater tanks are compulsory on most new houses in Sydney to meet a mains water saving target of 40 per cent.
Auckland councillor Daniel Newman, who has worked for Watercare, said dealing with consenting issues to install water tanks is a modest suggestion.
The bigger issue, he said, has been the planning failure to address water security and transport while tackling the housing crisis.
"Packing in housing, whether townhouses, apartments, greenfield subdivisions and infill housing has triggered more and more demand for services that we simply do not have.
"Warning of chronic infrastructure deficits were ignored when preparing the Auckland Unitary Plan," Newman said.