Christchurch City Council is introducing water restrictions from Saturday.
The city's quake-damaged infrastructure has been struggling to deliver normal service to residents.
The council says the restrictions will stay in force until February next year and could be replaced by an outright ban if water is not conserved.
Residents of odd-numbered houses can water their gardens and wash their cars on Wednesdays, Fridays and Sundays.
Those at even-numbered addresses can do the same on Tuesdays, Thursdays and Saturdays.
