Traveling to Mexico in 2 weeks, question about food prep...?

We are going to the same resort in Playa Del Carmen that we went to last year. We each got a little sick to our stomics by the end of the trip, nothing unmanageable. The resort has a water filtration system and bottled water, but do you think it happens to foreign travelers because of the water used in the preparation or just different kind of preparation that you are used to or that and a combination of over indulgence? We loved it there and cant wait to go back and will take precautions to stay well, just want to get other travelers insights.