Saad-Eddine El Othmani staged the publicity stunt in front of flashing cameras after environmental groups said it was being tainted by waste from two nearby prisons.
“This water is drinkable,” he told journalists as he sipped a glass from the Sidi Mohamed Benabdallah reservoir on the coast between capital Rabat and Casablanca.
“You are in good hands,” the premier said.
The authorities in the North African kingdom have scrambled to defuse reports over the pollution that have caused consternation among locals.
The national water authorities have insisted there is “no danger to the health of consumers”.
The issue has reached the country’s parliament with the official in charge of the nation’s water supply summoned to give an explanation last month.
The official Charafat Afailal admitted there was some wastewater being discharged into the reservoir but said that it remained “clean and drinkable”.
