How are you going to find and maintain your water supply safe and consistent when disaster strikes?
Many people that are not aware of the dangers salt water exposes human body to can think that the Earth's surface is more than half water so there's plenty of it do drink.
You've probably noticed the use of chloroform in many movies: pour some liquid onto a piece of cloth, place it on the victim's mouth and nose and knock them out.
This, of course, can be one of its uses, but initially chloroform was used to knock people out before a surgery. It was a kind of anaesthetic.