Piercing the bag before boiling it is part of why I wanted about 50%+ more space than was really needed compared to the frozen volume of the water. Water vapor has a lower density than the solid, but I was thinking if you had that much space to "inflate" with the steam, it should be good enough to bring the water up to about 200, which will kill most things short of hard cysts like crypto and anthrax. As a result, I don't think you'd need to have to worry about pressure equalization.

I only took two years of chem in college. Blast, this sounds like it is up your alley.
given:
-water (bag and heating volume) have an initial volume of ~10C
-amount of water to be heated is 1000g, give or take.
-max volume of the containment vessel is 1500 to 1600ml
-minimum air is contained in the containment vessel

query:
-Will the combine volume of liquid and gaseous water at 100C displace more than 1500g of liquid water at 10C?


I had planned on using ice (probably one to three blocks rather than cubes, say molded in a tupperware container, to keep the amount of air down) because of concerns about the vaccum pump sucking out more than air. You've never had a problem with the pump doing this, or do you always leave air in? I wanted to remove as much air as possible, which is another reason why I wanted to boil the water- it forces out the dissolved air. I"d rather not have the extra bulk.

It does sound like I reinvented the wheel, but I'm glad to see it works. Sounds like you've stored for two years- still potable? Ands are you using clear or silvered bags?