The best way to maintain a hydration bladder is to rinse and drain the unit after each use, especially when using a liquid other than water in the bladder. For more thorough cleaning, use 2 tablespoons of bleach diluted in water and then rinse with a mixture of water and baking soda. Manufacturers sell cleaning kits that include brushes and drying racks to help maintain the device.
Leaving liquid inside the bladder sometimes causes mold spores to grow and discolor the translucent vinyl. Cleaning with the bleach kills the mold and makes the unit safe to use again, even though it remains discolored. Baking soda helps to deodorize the vinyl and remove any remaining chlorine smell. Hydration bladder manufacturers also offer carbon dioxide cleaning tablets that clean the unit without leaving an unpleasant flavor. Other cleaning options include water-bottle cleaning tablets or denture cleaning tablets, both of which fizz in water to bubble away stuck materials from the inside of the bag.
The manufacturer's cleaning kit includes a small brush designed for cleaning the delivery tube and a larger brush for the bladder itself. These brushes give the user access to areas inside the unit that are otherwise difficult to clean. The drying rack holds the bladder open so any water remaining inside evaporates naturally.