Your in great shape, you’ve set aside your supplies and have your plans set for when it starts.
You only forgot one thing, leaving the water purification tablets on the counter as you strap on your day pack and head out the door to sneak to your first Jump Point.
You get to you two bedroom apartment on the outskirts of town just in time. The last vestiges of the military are flailing, dropping incendiary weapons onto the city, but your far enough out to just breath a little smoke.
The average adult produces 1.5 liters of urine a day and loses another .5 liters through breathing, sweating, and bowel movements. So, even at 1 liter per day rations while you are mostly stationary, you are going to run out of bottled water pretty quickly.
No problems right? You were able to put another thirty liters into the bathtub before the tap went dry. It might not be the most appetizing prospect, but your thirsty.
The problem is that your so used to drinking heavily filtered and purified water, that you are going to go through a period of GI adjustment. Plan on intestinal cramps, pain, diarrhea for at least a few days as you transition away from municapal water supplies.
To start with, purification tablets are a good, simple way to make sure you won’t get something that will knock you out. Filters are okay, but they are more bulky, and they tend to wear out without really giving you any notice that they are no longer working.
Boiling, is of course a gold standard, but the risk of fire bringing down the horde is too great until your well situated at your final jump point.