Vanuatu offers many major international alcoholic beverages including beers, liquors, and wines, however they are expensive and their availability is limited. Many locals prefer to drink beer, most commonly the local beer "Tusker."
Generally speaking, the tap water is not safe in Vanuatu. There are exceptions to this, most particularly in the larger towns and cities, but in the water is not consistently safe anywhere. Check with locals before consuming the water and if you do decide to drink the water, remember that many people may have troubles adjusting to the local tap water as it will most certainly be different from what your system is used to.