Authorities have ordered a halt to pumping water out of a lake near Rome following a prolonged drought, a decision that could force city officials to impose water rationing in the Italian capital.
The head of the local Lazio region, which is centred on Rome, said on Saturday the ban on withdrawing water from Lake Bracciano would come into force on July 28.
"Sadly, it is a tragedy," Nicola Zingaretti told Tgcom24 TV station. "The truth is Lake Bracciano has fallen too much and we risk an environmental disaster."
Acea, the utility firm which runs Rome's water system, has said that two years of lower-than-average rainfall have dramatically reduced water levels in reservoirs feeding the city, with a prolonged, ongoing heat wave making matters worse.
But Acea attacked the order to turn off the taps at Bracciano, which is some 30 km north of Rome, saying the region had taken a "unilateral and illegitimate" decision.
"The drastic reduction of the flow of water into the capital's water network will force us to introduce a rigid rotation of supplies that will impact 1.5mn Romans," an Acea spokesman told the national Ansa news agency.
Zingaretti said only 8% of Rome's water came from Bracciano, adding Acea had the time to find a solution.
Earlier this month, Acea started to close the drinking fountains that dot the city in an effort to safeguard supplies.
Since then there has been no let up in above-average temperatures, with 2017 likely to be one of the hottest years on record in Italy.
"I would like to invite Donald Trump here to let him see what it means not to respect climate accords," Zingaretti said, referring to the US president who last month pulled the United States out of the 2015 Paris accord to fight climate change.