Most travellers know this rule, but it is a big one: Usually do not consume the tap water. Faucet drinking water isn't safe to consume in Cancun, because it's rampant with parasites and perhaps deadly micro organism, and non-locals are exceptionally at risk of obtaining Unwell from non-filtered drinking water. https://cesarlcqdp.blogtov.com/12204180/detailed-notes-on-cancun-trip-tips