How long can an elderly person live without water?

A person will probably die without water after 5 days, but will suffer serious, effects after 3 days. Death by dehydration is a nasty process involving incessent skin irritation, halucinations, and the swelling/ cracking of the tongue. 3 days without water is a serious threat to survival. All of the figures that I have read say 10 to 20 days without food. Obviously, this depends upon your weight to begin with and your state of health before the eating stopped. An overweight adult will last longer because they have more reserves to work from than a thin person.