How do a few people can survive without the water

I heard some people are allergic to water but this is very rare condition and how can they survive without the water?

Aquagenic urticaria, also known as water urticaria and aquagenous urticaria, is a rarely diagnosed form of physical urticaria. It is sometimes described as an allergy, although it is not a true histamine-releasing allergic reaction like other forms of urticaria. The defining symptom is a painful skin reaction resulting from contact with water. This may also be the effect of different temperatures of water, such as cold or hot and can flare with chemicals such as chlorine.
There is no known treatment for aquagenic urticaria. Dermatologists recommend avoiding contact with water as much as possible by taking short showers, staying cool, and avoiding rain to ease symptoms. Antihistamines, Zostrix, and other types of medications may be prescribed to help reduce the intensity of the reaction. In some very mild cases a medicine such as benadryl can be taken to relieve the hives.