Most all inclusive resorts there have their own filtration plants, or Cancun has one for the whole place I think. I still don't drink the water unless I have to. Drink the bottled stuff whenever you can. The ice is made of it, but plenty of alcohol will help. Or just drink beer.
They say not to tip at the all inclusive resorts, but everyone does and it helps get you better service. Just scope it out on the first day and see what's going on. You might have to keep it on the down low.
For your own safety, DO NOT LEAVE Cancun Island. The neighboring city of Cancun is the hood and you might find yourself to be a statistic.
If you're into fishing, find out what's around this part of the year and only book a trip with a reputable fishing service. These can be booked at the hotel.
