Another lesson akin to the Spark Lite disintigration in another thread. I was going through my water containers, refilling them after a move and found that one of them had a small crack in the spout cap. It wasn't big and if I hadn't been paying attention I might not have seen it - it was big enough to let air in.

*Gets out calendar and schedules a day for detailed equipment checks*

EDITED to add that the containers in question are 4 gallon Aquatianers by Reliance.

I am also in the progress of turning my water and fuel supplies around. I completed equipment checks last month.