Drink only bottled water. Most restaurants and bars use purified water, but feel free to ask to be sure. When cooking or preparing vegetables for salads, use products such as “Microdyn” to purify the water you use to clean them. You can purchase Mircodyn at all the local grocery stores.When staying in a vacation rental the proprietor will usually have one or two five-gallon bottles of water for you to use. If you run out just listen for the horn of the water delivery truck, flag him down and for a few pesos you can purchase a five-gallon bottle of water.