I use a carbon water filter out in my brew shed because its fed from a standard garden hose. I like it because it not only gets rid of the chlorine, but also those little nasties with legs that always find their way in to your hose.
How should I be storing this filter when not in use? Should it be drained and allowed to air dry? I've heard some people say they just leave the water in it and just flush it before the next batch. I'm thinking any time you have wet media and air you are likely to grow nasties. If it stays wet, just how long can that water stay in there before it starts to grow stuff?