> What makes long term stored water go "stale" or unuseable?

From 72 Hour Kit, I gather the main problem is things living in the water. Here's a quote:

Since you're essentially starting with virtually sterile water, what you're mostly concerned with is any bacteria that might be introduced during the filling process, as well as any odd bugs that got through the disinfection treatment and may just not be there in large enough quantities to normally cause a healthy person any problems. You want to make sure they don't multiply and create a problem given the time.
_________________________
Quality is addictive.