Your Berkey® Sport Bottle Filter has a 50-year shelf life! When not in use for an extended period of time, remove the filter and fill the unit with bleach at a rate of one-quarter teaspoon per 2 liters of water, or a 50/50 mixture of 3% hydrogen peroxide. Rinse. Allow the parts to dry completely with the cap removed. Reassemble the assembly and store if possible in an airtight bag. Do not allow the filter to freeze, do not place it in the microwave, and do not run hot water through it.