I've been told, and read that BAC water, once the rubber top has been punctured is good for 30-45 days. I keep my BAC water refrigerated. When they say it isn't "good" anymore what exactly does that mean? Is it less effective somehow, does it effect the integrity of whatever you're mixing? Does there become a risk of infection? It seems like if the water is sterile, and it's only been in the bottle, then it should be just fine. What's your take?