On a typical winter day Hamilton would use about 50 million litres.
The treatment plant beside the Waikato River has a peak production capacity of 106 million litres per day, although Hamilton must stay within its water uptake consent limit.
Recent water usage figures from council show 40 per cent of water being produced at the water treatment plant is not being returned into the wastewater system, so is largely being used in gardens and for outdoor purposes.
"We need residents to stick to the city's current sprinkler restrictions, and to be smart about their non-essential water use, especially outside."
Last year, Hamilton had been on water alert level one through the start of March, before all restrictions were lifted by March 27.
Water blasting to clean Victoria Bridge may be affected if the city moves to water alert level three.
An approved water management plan is in place to ensure the efficient and considered use of water. If the city's water alert level moves beyond level two, water use for the project will be reviewed.
NIWA reported on Monday that it was officially New Zealand's third ever hottest summer on record, as daily maximum temperatures continue to remain in the mid 20s throughout March.
Weatherwatch has said that record-breaking heat in Australia has moved over to New Zealand meaning this week and next week would be warmer than average for most parts of the country.
"Central Otago, inland Canterbury, Nelson, Marlborough, King Country and Waikato all have highs last Sunday and/or next week of around 27 or 28 degrees, some pockets may even reach 30 ," a Weatherwatch statement says.