It is perfectly safe to drink water straight from the tap in Cancun. However, it is highly recommended that you buy bottled water. Bottled water, depending on size, typically costs 20-50 pesos ($1.87-$4.62 USD). Most of the resorts in Cancun have purified water at all of the facilities located inside the resorts including the bars and restaurants. The upper-scale restaurants usually have purified water as well.