Preparations for Calamity

My colleagues and I have made it perfectly clear, with compelling evidence, that great calamity is about to befall much of the human race.
It is advisable to be prepared for worst-case scenarios, and of course one of the most vital things for the human body is water

A lifestraw I would highly recommend. For what they do they are relatively inexpensive, and will completely remove all harmful bacteria and pathogens as well as particulate contamination. It will filter enough water to keep one person hydrated for twelve months. The only things it cannot do is desalinate water, so seawater will not be rendered drinkable with this, nor will it remove flouride. But it could mean the difference between death and survival