According to the Numbeo water drinkability and accessibility index, tap water has a score of 66 / 100 (100 being best).
Numbeo considers this score to be "High"
We are working on providing you with scientific reports about the water quality in San Cristobal de las Casas, if you know a reliable source for that feel free to shoot us a message in the chat below or in the comments!
1 adult could save about 438$ per year in San Cristobal de las Casas by drinking tap water instead of buying bottled water.
๐ณ Drinking tap water would also help with reducing your plastic footprint and improve environmental pollution.
Like in most countries, water quality and accessibility differs from location to location, therefore it's the best to check the information available on that place.