By the numbers: How Tauranga's soaring demand resulted in water ban

Alex Grace, 3, dashes under the sprinkler at his house this summer but water restrictions are being considered by councils. Photo / Peter Meecham

A record amount of water use in Tauranga has prompted a sprinkler ban to help curb the city's soaring demand.

People have been asked to completely stop using all sprinklers and irrigation systems until further notice. The city's current water demand is up by 40 per cent on normal average water use.

Water restrictions are imposed when the rolling average is above 50,000m3 a day for more than five days, with no rain on the forecast, and a council spokeswoman said water usage was tracking above that.

Average usage during the year was around 41 million litres per day. On Monday, demand hit 58 million litres - the highest use on record since water meters were installed.

City waters manager Stephen Burton said hot, dry weather meant water usage started climbing as early as November.

In 2019, Tauranga used 15.1 million cubic meters of water. In each 2018 and 2017, the city used 14.1 million.

Last year the council collected $23.4m in revenue from water rates. In 2018, it collected $21.6m and in 2017, it collected $20.2m.

Burton would not answer questions of who the three largest commercial water users were in Tauranga but instead said the council worked with them "to optimise their water use during water restrictions".

"The bulk of the water use within the city is for residential purposes. The ongoing residential growth is largely driving the need for water supply to be supplemented," he said.

Tauranga's water comes from two spring-fed streams, the Tautau and Waiorohi.

The primary driver for peak summer demands in Tauranga was outdoor water use, which was often the focus of restrictions such as a sprinkler ban when they were introduced.

The last water restrictions imposed by the council were during January 30 and March 25, 2019. Water restrictions were also imposed during the summer of 2017/18, which was the first time in 17 years.

The next step will be a hose ban.

In the Western Bay, the last time water restrictions were brought in was 2013.

Utilities manager Kelvin Hill said this was due to residents responding to calls to conserve water use, which was now needed.

Hill said the council was on "high alert" and seriously considering also imposing water restrictions.

Reservoirs in the Western Zone of Waihī Beach and Katikati and Central Zone of Omokoroa, Te Puna and Minden were only just maintaining the necessary levels to supply residents, Hill said.

Reservoirs must maintain a constant 50 per cent minimum water level to meet the daily demands for drinking water. The Western and Central reservoirs are currently at 55 to 60 per cent but could not afford to drop, he said.

"Many councils in New Zealand were already restricting water. If demand from our residents doesn't reduce over the next few days – our next step would be to ban sprinklers (hand-held hosing only) and introduce water restrictions for odd-numbered houses on odd days and even-numbered houses on even days."

Rotorua Lakes Council was also calling for residents to reduce their water usage. While water restrictions were not currently being considered for the district, they would if water usage continued to increase, said water operations manager Eric Cawte.

How the keen gardener survives in summer

The sprinkler ban won't affect Jennifer Custins much as the passionate gardener has been practising sustainable water techniques for a long time.

Bay Gardener member Jennifer Custins. Photo / Andrew Warner

But the Bay Gardener member said limiting water use was a vicious cycle due to the environmental benefits plants have.

"When I was closing my blinds last night I could see that one of my big trees was going to die so I went down and put several buckets of water on it.

"It is the sort of thing where you ask 'am I going to save a tree because we are having a really dry patch or do I save it for the environment?'."

It's just a few litres of water, for now, she said, although those litres of water can be saved from the shower while people are waiting for the water to heat.

"Water is a necessary component but it is a bit of a vicious circle. If you don't keep these things watered people's health is affected adversely in another way.

"However, I would definitely adhere to a sprinkler ban. People really shouldn't be using them these days."

Custins said installing a good irrigation system, such as the weeper hose which lies under the soil and slowly disperses water is the best solution to a thriving garden.

"We are living in more and more drought so water is precious, but there are ways we can change."

Tauranga residents can continue to water their gardens, by hand-held hose between 5am and 8am, and from 7pm to 10pm.