Water is essential for surviving more than a few days and will be your #1 priority in a survival situation. On average we can survive around 3 days without water. If SHTF and you don’t have a source for water or the means to purify it, you will likely die fairly quickly.
I have found an extremely informative website on how to find, filter and purify water. They break everything down and explain it all so you don’t miss a thing. From water facts, to do’s and don’t’s, to sourcing, filtering and purifying water, this is a veritable 101 on water.