Sunny days are set to continue until at least December 7, MetService says.

Most of the Wellington region is "right on the cusp" of running short of water, and is facing the prospect of an outdoor water ban.

Daylight saving water restrictions are already in place across Wellington, Porirua and the Hutt Valley. But with many of the region's water bores out of commission for repairs and a string of dry, 20-degree days forecast to last into early December, Wellington Water is weighing up its options.

"We are right on the cusp of not having enough," manager of treatment plant operations Jeremy McKibbin said on Tuesday.

SUPPLIED A total sprinkler ban might become necessary if water use does not fall, and a ban on all outdoor watering is not off the table.

"If there is no letup on demand and it keeps dwindling, then we are going to have to put emphasis on restrictions."

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Maximum capacity is 169 million litres a day, but demand had been exceeding 170m litres, he said.

WELLINGTON WATER Only four of the eight Waterloo bores that supply the Waiwhetu Aquifer were working in July. That number is now down to three.

Water levels were dropping faster than demand. "If we allowed it to carry on, we could run out."

A total sprinkler ban might have to be introduced if demand did not decrease in the next fortnight, he said. A total outdoor water ban was not off the table.

We've been having a pretty hot November, so while you're enjoying 🍦 in the ☀️, please remember to conserve 💧 out in your garden.

Watering restrictions are currently in place: https://t.co/8iaIq9judV#waterfact #waterrestrictions #ourwaterourfuture pic.twitter.com/d9oxHSQ8gT — Wellington Water (@WgtnWaterNZ) November 23, 2017

VIRGINIA FALLON/STUFF The Kāpiti Coast is unlikely to face water restrictions this summer, thanks in part to its introduction of water metering.

To curb demand, people should look at prioritising household use over gardens, and residents should be more mindful about their general usage – such as not leaving taps running when brushing teeth, McKibbin said.

The early dry spell hit just as upgrades to equipment at the Waiwhetu Aquifer and Te Marua were being carried out. "[It's] incredibly bad timing."

E-coli was found in water drawn from the Waiwhetu Aquifer on three occasions since late last year, and an increase in coliform bacteria was also detected.

Chlorination was introduced immediately, and a new ultraviolet treatment plant is currently being installed.

In the summer months, the region may rely on up to eight separate bores, but while the ultraviolet treatment plant is installed just three are operating.

"We'll be back up to full flow in January," McKibbin said.

KĀPITI DODGES RESTRICTIONS

Kāpiti Coast residents, meanwhile, are unlikely to face water restrictions, partly thanks to metering introduced in 2014.

Water meters, in conjunction with the new Waikanae River recharge scheme, meant Kāpiti Coast District Council had enough water to manage even the worst drought conditions, infrastructure services group manager Sean Mallon​ said.

Since meters were introduced, peak water consumption had fallen by more than 25 per cent.

THIRD DRIEST NOVEMBER ON RECORD

Wellington is tracking for the third driest November on record since 1928.

"There is no meteorological drought right now, [but] it is certainly drier than normal," Chris Brandolino, principal scientist forecasting at Niwa's National Climate Centre, said.

Seventeen millimetres of rain has been recorded at Kelburn since the beginning of the month.

Upper Hutt is also on track for the third driest November, with just 22mm since the beginning of the month.

"The temperatures we have had are warmer than average, and that is set to continue for the next few weeks," MetService meteorologist Tui McInnes said.

A string of dry, 20C days were set to continue until at least December 7.

"It is quite unusual, especially in November and for this long."