"A gallon a day will help you stay hydrated and prepare food. If you have all dehydrated food and you want to wash up, you'll need more. The average person has a 50-gallon hot-water heater at their house. If the power goes out, you can turn that off and drain the water from it – that's a lot of water people have access to."
Mark Ruffalo's Good Life Formula
How Hollywood's greenest star found peace.
Plus: The New Whiskey Masters
ON NEWSSTANDS NOW
Sign up to receive the Men’s Journal newsletter and special offers from MJ and its marketing partners.