Stuff like cholera is one of the reasons why military ration packs include water purification tablets.

It's also one of the reasons why the British military rat-packs include teabags and boil-in-the-bag food. You can cook your dinner and make a nice hot cup of tea. at the same time.

Anyway, here's a link to the BBC's decription of the British 24-hour rat-pack. Worth reading (and the comments) for anyone who has time to do a little preparation.

http://news.bbc.co.uk/1/hi/magazine/4221838.stm