Cambodia: It's not recommended to drink the faucet water in Cambodia. Filtered water is a better choice; try to use a refillable canteen or water bottle rather than buying bottled water. Remember to avoid freeze in drinks and peel fruit before eating.
Vietnam and Laos: Drinking tap water isn't recommended in Vietnam and Laos. For environmental sense, decide to avoid buying bottled water. Fill a reusable water bottle or canteen with filtered hydraulic instead. Ask your leader where percolate water can be found; some hotels we support in may have drinking water valid. It's also advisable to avoid ice in drinks and peel fruit and vegetables before eating.