Here's a step-by-step guide on how to dry a water bladder
1. After rinsing the hydration bladder, dump all of the water out and drain the hose by squeezing the mouth piece and lifting the reservoir higher than the mouth piece.
2. If you can reach your hand in the fill opening, dry excess water with a paper towel or a clean dish towel. If you can't fit your hand in, no big deal, it will just take longer to dry completely.
3. Leave the cap open and hang the reservoir to dry. Many CamelBak hydration reservoirs come with hidden dryer arms that keep the reservoir open when it's hung upside down. If your water bladder doesn't have dryer arms, make a water bladder drying hanger, as seen in the picture below. Use a saw to cut the hanger near the top on one side. Cover the cut ends with tape, so they don't puncture the bladder. Hang the water bladder on the hanger.
4. Drape the hose around the top to keep it from dragging.
5 Hang in a cool, dry location
6. Let the bladder dry completely before storing it.
Now that you know how to keep your water bladder dry, you won't have to worry about getting rid of an off taste or moldy residue. You can just fill your reservoir with water, tuck it in your pack and head out for your next adventure.