The head of Watercare says if New Zealand wasn't in the Covid-19 lockdown, mandatory water restrictions would have been introduced for Auckland due to the low levels in region's dams.
Auckland's nine water-storage dams, in the Hūnua and Waitākere Ranges, are just 52 per cent full as the drought continues to bite.
While encouraging Aucklanders to continue to wash their hands, Watercare is asking them to think carefully before turning their taps on and especially to limit outdoor water use.
Chief executive Raveen Jaduram said that as well as the drought, the lockdown was not helping.
"People are home and therefore their outdoor consumption seems to have increased, so demand has gone up.
"We want everyone in Auckland to realise how severe this issue is. Half-full storage lakes in April - we haven't had that since about 1992."
He said if it weren't for the lockdown, Watercare would impose mandatory restrictions on Auckland now.
"We feel that people are feeling anxious and worried already because of Covid-19 and we don't want to add to the stress by putting restrictions," he said.
"It's also difficult at this stage for us to put restrictions and then go out into properties if people are not obliging. [But] if Aucklanders continue to use a lot of water, then we will have no choice but to introduce water restrictions, possibly by the end of the month."
Jaduram said if the water level went down to, say, 20 per cent, then it would also require additional treatment.
"It gets very murky and concentrated and so it takes more to treat, but we hope we don't get there. We want to be at the pristine level, which is where we are at the moment. So at the moment, that is not a challenge."
He stressed that washing cars and waterblasting houses was not essential right now.
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"We've got two choices: We can wait for the rain, or we can reduce our demand or we can do both. But we are at the mercy of the weather here. And we know with climate change, and with everything else that's going on, we need to change our behaviours."
Watercare's advice to Aucklanders
• Keep washing your hands regularly.
• Keep your showers short: four minutes or less.
• Only run your dishwasher or washing machine when they're full.
• Limit your outdoor water use.
• Don't wash the car.
• Don't waterblast the house or driveway.