E coli detected in Lower Hutt's water supply following last year's earthquake is behind a warning for Wellingtonians to conserve water.

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On Sunday, residents in Wellington, Porirua and the Hutt Valley consumed 30 million litres more than on a typical day - a volume not seen in November since 2012.

Wellington Water said the good weather, coupled with upgrades to treatment equipment for water from the Waiwhetu Aquifer and Te Marua lakes, meant there was reduced supply.

It reminded residents water restrictions were in place.

Treatment plant manager Jeremy McKibbon said until a new plant was up and running in January, supply was limited.

"So we're putting a system in place to treat any potential bacteria that might be in the aquifer water.

"And until that system's in place we're restricted on what bores we can use because of the possibility of bacteria in those bores."

Mr McKibbon said residents of odd-numbered houses could water on odd-numbered days between the hours of 6am and 8am, and between 7pm and 9pm.

Even numbered houses could water during those hours on even-numbered days.