As a severe drought continues to hammer Auckland Watercare is calling for residents to reduce their water usage rapidly, or face potential restrictions.
The Hunua and Waitākere ranges, home to the city's water storage dams, have received about 65 per cent less rainfall than normal since the start of the year and storage levels have dropped to just 53 per cent.
This time last year the dams were at 71 per cent, with the average for this time of year 78 per cent.
Despite daily water usage dropping since a peak of 565 million litres in February, it has started to rise again this week with more people at home and a run of fine weather.
The extra usage has been partially offset by the fact that construction and other forms of industry are temporarily on hold during the lockdown, but Watercare is warning if Aucklanders don't change their habits, mandatory restrictions will come in.
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Watercare chief executive Raveen Jaduram said under these conditions they were asking Aucklanders to think "carefully" before turning their taps on, but to not let it get in the way of good hygiene regarding Covid-19.
"While we encourage everyone to wash their hands regularly, we ask that people limit their outdoor water use.
"Washing your car and waterblasting the house is not essential right now."
A four-week weather forecast provided to Watercare by MetService showed more drier-than-normal conditions were on the way.
"We are expecting some rain next week, which is extremely welcome.
"However, a day or two of rain is not enough to break a drought.
"We need sustained rainfall over several weeks for our water storage dams to replenish."
They were hoping this would arrive by May or June.
"In the meantime, we all need to do our bit to reduce our water use."
To reduce demand on the dams, Watercare had been maximising production at its Waikato and Onehunga treatment plants, which draw water from river and aquifer sources.
Watercare also introduced a "Water is precious" campaign at the start of February, which Jaduram said Aucklanders had been responding to positively.
One of the key messages was the four-minute shower challenge, with showers responsible for 27 per cent of household water usage.
Aucklanders on average spent eight minutes in the shower, so halving it was estimated to result in about 80 million litres of water saved.
At the peak of usage in February the city was swallowing up 565 million litres a day, but since then, amid the Covid-19 lockdown which has reduced industrial usage, demand has fallen by about 80 million litres a day.
However, with a run of fine weather this week it has started to increase again.
Although total storage was much lower than capacity, Watercare did not intend to implement formal restrictions at this stage but did not rule them out if demand continued to rise, Jaduram said.
"Aucklanders have proven they're excellent at being water efficient – we're just asking the community to be even more mindful and to cut back a lot outdoors.
"With many people spending their days at home, its tempting to tackle outdoor chores and run the hose all day. We ask that you don't wash your car or water blast the house. Please hold off until we've had several weeks of rainfall.
"On Tuesday we had a spike in demand brought on by the stunning weather and people doing water blasting/car washing/watering their gardens. Boredom is no excuse and if this continues, we will be in a serious situation and will have to bring in mandatory restrictions."
Niwa meteorologist Ben Noll said it had been an "incredibly dry stretch", going all the way back to late 2019.
Auckland and Northland, also still under drought conditions, were "incredibly unlucky" to miss out on decent rainfall from ex-tropical cyclones Uesi and Gretel, which both passed just north of the country.
"They were tantalisingly close, and if they were just 200km more to the west, could have ended the droughts."
Niwa's rainfall gauge at Western Springs recorded just 23mm in March - the fourth driest March on record.
The dry run would continue this week and into next, Noll said.
Late next week a change in the weather patterns was expected with a strong westerly flow directing fronts up the South Island's West Coast, with some reaching the upper North Island.
"There will be some rain, but overall it is looking like more drier-than-normal weather."
Water usage this week
• Sunday: 464 million litres
• Monday: 466 million litres
• Tuesday: 485 million litres
• Wednesday: 480 million litres
Watercare's advice to Aucklanders
• Keep washing your hands regularly
• Keep your showers short: 4 minutes or less
• Only run your dishwasher or washing machine when they're full
• Don't wash the car
• Don't waterblast the house or driveway