Italy's Health Minister Beatrice Lorenzin has warned of health consequences if water rationing is imposed in Rome.
Parts of Italy, including the Lazio region around Rome, are suffering from drought.
The water company that serves Rome is proposing cutting supplies for eight hours a day to 1.5 million residents.
Water utility Acea blames a decision by officials to stop it taking supplies from a nearby lake.
The authorities that run Lazio say levels in Lake Bracciano have fallen too low because of the drought and they fear an environmental disaster.
Ms Lorenzin said: "An eventual suspension of the supply of water in Rome could seriously compromise the level of hygiene of all the accommodation structures, restaurants and public offices.
"But above all, it could seriously compromise the provision of essential health services."
Acea has criticised the decision to prevent the use of water from Lake Bracciano and said it had no choice but to introduce rationing.
But the water company and the regional authorities say they will continue to try to find a solution.
Italy has suffered its third-driest spring in 60 years, affecting two-thirds of farmland and costing Italian agriculture some €2bn ($2.3bn; £1.8bn).
There have been two years of lower-than-average rainfall in Rome.
So dire is the situation that the Vatican began shutting off its famous fountains on Tuesday.
- 60% of farmland under threat
- 10 regions prepare natural calamity requests
- Estimated cost to agriculture is €2bn
- Dairy farmers, wine grapes and olive production among the worst hit
- Rome, the capital, faces water rationing
- Some of the city's drinking fountains have been shut