Complicating the excessive water losses at altitude is the difficulty consuming adequate fluids. The sensation of thirst does not keep pace with water loss. Individuals do not feel like drinking, even when they are already dehydrated. AMS further exacerbates the dulling of the thirst sensation. Other symptoms of AMS include headache, nausea, vomiting, and the loss of appetite.
Potable water is difficult to obtain in high-altitude environments.
Because of the large water requirement at altitude, a day's supply cannot be carried by an individual soldier. When temperatures are very low, water in canteens and bulk water containers may freeze, restricting water availability. All melted snow and ice, as well as water from streams, should be considered contaminated. This amounts to an additional minute for every 1000-foot gain in altitude. For example, at 14,000 feet, water needs to be boiled for 24 minutes to be purified.