Christchurch's capacity to keep its water reservoirs filled is likely to be stretched this weekend unless people heed advice to conserve water.
With temperatures in the city tipped to exceed 30 degrees over the next couple of days the city council is concerned high demand for water could impact on the city's water supply network.
The city council will make a decision on Monday whether to introduce water restrictions.
This means people would only be permitted to use hoses, sprinklers and garden irrigation systems every second day.
"The problem is not that we don't have enough water. The problem is that when it gets really hot we struggle to get the water through the pipes and into the reservoirs fast enough to meet the high demand,'' said city council head of three waters and waste John Mackie.
"If we can't keep the reservoirs filled, the pressure across the network drops. It also leaves us exposed in the event of a fire because having sufficient water in the reservoirs is essential for fire-fighting.