Avoid Tap WaterAs a general rule of thumb while on vacation, don't drink the tap water. Some hotels have signs warning against it, but even if there are no clear disclaimers, err on the safe side anyway. For drinking water, always stick to purified water bottles. To brush your teeth, also consider using the bottled water. However, if you have a limited supply and must use the tap water, just be sure not to swallow any of it. And don't forget to keep your mouth closed while in the shower!
Be Careful About BeveragesIf you're unsure about the drinking protocol in your particular vacation spot, ask around. As the saying goes, do as the locals do. For example, in Mexico, the locals don't drink tap water; many have purified gallons of water delivered to their home instead. As far as other beverages go, typically if it is fermented, carbonated, or pasteurized, it means there is little to no bacteria, as these processes tend to kill contaminants. So if you're looking to let loose and have a few beers or glasses of wine, knock yourself out. And in the morning, don't be afraid to order that tea, canned soda, or coffee.
Inquire About IceIce in hotels and resorts is usually okay; however, it is something you want to ask about. Larger hotels often have ice shipped from distributors, but it's not something you just want to assume. Make sure that they use purified water. In restaurants, opt for beverages without ice, just to be safe. The important thing is to err on the safe side and don't be afraid to ask hotel staff and the locals about water safety and usage. Drink and use bottled water whenever possible. To be extra cautious, and ensure safe drinking water is never an issue, consider bringing a water bottle filter with you in your travels.