It’s a suggestion alien to Mexico City residents who have long shunned tap water in favor of the bottled kind and to the throngs of tourists who visit the city each year, bringing with them fears of “Montezuma’s Revenge.” But a law recently approved by Mexico City’s legislators will require all restaurants to install filters, offering patrons free, apparently drinkable potable water that won’t lead to stomach problems and other ailments.

“We need to create a culture of water consumption,” said Dr. Jose Armando Ahued, health secretary for Mexico City. “We need to accept our water.”

Bad tap water accounts in part for Mexico being the highest consumer of bottled water and — worse — soda, some 43 gallons per person a year. With an obesity epidemic looming nationwide, the city’s health department decided to back the water initiative.

Mexico City officials say 65,000 restaurants will have six months to install filters once the bill is signed later this month. Health inspectors will make periodic visits and impose $125 to $630 fines to those not complying. The law doesn’t cover thousands of food stalls along Mexico City’s streets.

Some restaurants already have the filters. Business consultant Jose Frank recently ate tacos with two colleagues at Yucatan Cravings in the Zona Rosa tourist district. They all had bottled water.

“I’m afraid to drink the water for everything they say. I don’t feel secure. I prefer bottled,” Frank said.

A general distrust of tap water is not without reason.