@pmbrandvold I use CPAP and distilled water. For awhile, we were refilling the plastic gallon empties with tap water to squirrel away as an emergency water cache.
I got a countertop distiller, too. I figured it's kind of a wash in terms of the energy to produce, ship, and then drive to pick up jugs from the store.
If I were really worried, I might look into something solar powered to slowly distill a gallon over the course of a week (since that's about how much I use)