Hamilton City Council is warning residents they need to reduce their outdoor water use or face further restrictions.
Water use has surged in the high temperatures this week, with Hamilton consuming the most water its ever used in three consecutive days, the council said.
More than 85 million litres of water has been used each day between Tuesday and Thursday, a more than 50 percent rise on average consumption.
Sprinkler restrictions are in place at the moment, but water use levels are close to triggering further restrictions and a complete ban on sprinkler use.
Council city waters manager Marie Porter was urging people to think about non-essential water use, especially outside.
"If you are using a sprinkler consider using a timer to reduce the length of time and ensure you stay within the restrictions. If you don't have a timer, set an alarm to remind you to turn the sprinkler off after a certain amount of time rather than guessing how long it has been on for," she said.
"If you're using a pop-up paddling pool this summer use a cover to prevent evaporation as well as the appropriate chemicals to keep the water fresh. These small changes can save significant amounts of water."