Temperatures in Shanghai reached 40 degrees Celsius on Saturday after a five-day heat wave, the municipal meteorology station said.
Over seven million cubic meters of mains water were consumed in the central urban area each day, the highest volume of the summer.
The heat wave is expected to continue this week.
An orange alert for high temperatures in southern and western regions remains in force, with temperatures over 40 degrees Celsius expected in some areas.
China has a four-color-coded warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.
