Officials in charge of Auckland's water supply have a new message they want to get across to residents - if it's yellow, let it mellow.
The recent rain that's fallen on the city has boosted the storage lakes by just 2 percent to 44.5 percent, well below the historic average of around 77 percent at this time of year.
"We need that sort of rain every day between now and summer," Watercare CEO Raveen Jaduram told The AM Show on Thursday.
Auckland's had its worst drought in 100 years over the past few months, prompting minor water use restrictions. It's helping, bringing the average daily use down from 440 million litres a day to 405 million.
But Jaduram has a few tips for how we could reduce usage even further.
"Keep a bucket in the shower - use that for other uses, like flushing the toilet. If it's yellow, let it mellow - and you know."
In case you don't, the full phrase is 'if it's yellow, let it mellow; if it's brown, flush it down'. Essentially, only flush the loo if you do number two.
"That's become standard in our house," he added.
Auckland already gets about a third of its water - 150 million litres a day - from the Waikato River. Watercare has resource consent to pull another 25 million, but only if the river flow is above average - which it isn't right now. Watercare is trying to get permission to waive that requirement, saying the Waikato isn't using its full allocation and has plenty to spare.
"We're discussing with Waikato Regional Council, we're talking to Waikato-Tainui. We've also approached the Hamilton City Council - they have water allocated to them they don't need and use. We have requested that they, on a temporary basis, transfer that to Watercare... They will let us know by the end of June at the earliest."
Auckland Mayor Phil Goff said everyone should be doing what they can to cut use.
"It might not seem that individual water savings makes much of a difference but collectively it does.
"If each of us have shorter showers, saving 12 litres a minute and reducing the 25 percent of householder water use that showers make up, we will save millions of litres of water a day. Running dishwashers and washing machines less frequently also helps.
"By saving water now, we can reduce the likelihood of severe water restrictions in summer."
Other options such as desalination and recycling wastewater will take too long to implement to ease the current shortage. Jaduram says a 2013 study showed the Waikato River was the best bet.
"We considered other options like desalination and purified, recycled wastewater, more dams - it's quite difficult to build more dams in Auckland. It's not just the cost - we take a series of factors into account. Money is one, the environment is another, the resilience of what we build. A dam would still be rainfall-dependent, and we've got two-thirds of our water coming from rainfall-dependent sources. Depending on the size it would be $200-$300 million...
"We are looking at more resilient - climate change taken into account - water sources to supplement the existing sources and treatment plants that we've got."
