This story made me so happy as the Italian couple seem so sweet. It took me about an hour and a half to get through the episode by looking up words I didn't know but such a great episode.
Here in Brazil we usually don't drink tap water, but I personally and the couple of friends I talked to here said they cook with it fine since it's boiled. But there's also special taps that kind of automatically filter all the water that goes through them. I personally use a regular coal filter. Idk how the situation in Mexico is different though.