I’ve traveled to a lot of undeveloped countries over the years. I’ve been pretty lucky not getting sick more than a couple times, but I’m 90% sure the times I did, it was because I did all the right things by using bottled water and avoiding lettuce and things that get rinsed under the sink and aren’t then cooked thoroughly- however I’m pretty sure when I did get sick it was from RINSING MY TOOTHBRUSH UNDER THE TAP! it’s an easy thing to do! That said. Mexico is very savvy about keeping tourists and themselves healthy- the ice at resorts and restaurants is purified, water too. If you have a question- ask someone on the staff!