The Wellington region's emergency water supply has already been tapped into, as rivers dry out in an unusually warm and dry start to summer.

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Wellington Water said just over 6 percent of the water stored in the Te Marua storage lakes had been used to top up the region's regular supply.

Community engagement manager Alex van Passen said it was important the water in the storage lakes lasted all summer.

"What's been really unusual about this summer so far is it's just so early for us to have been tapping into our lake supply, it's just unheard of really for us to be using lake water to supplement that river and aquifer supply in November."

Mr van Passen said water use had dropped to 161 million litres a day, and if it stayed at that level, the lakes should last until the end of summer.

He said during the Christmas holiday period water demand usually dropped off, and some ground could be gained supply-wise during that time.

But he said restrictions on water use were expected to stay in place.

Wellington Water's manager of treatment plant operations Jeremy McKibbin said there had been a drop in water usage on Friday.

He said if people continued to be careful with their water there was no reason there would be a total ban on using water outdoors.

A sprinkler ban was put in place in the past week, but people could still water their gardens with a hose.

Dry in Canterbury

Fire and Emergency officers are asking people in Christchurch and the Selwyn district to make sure their properties are fire-safe, after the driest November on record.

A Christchurch weather station that has been running since 1864 recorded only 1.4 millimetres of rain in November.

It was even drier in Lincoln, which got only four-tenths of a millimetre.

The principal rural fire officer for the area, Darrin Woods, said a restricted fire season will be declared next week.

He said they hadn't seen a month with such little rainfall since probably December 2003.

Darrin Woods said people should clear vegetation around their homes and mow lawns in the morning - when it is coolest - to prevent the risk of sparks from mower blades starting fires.