After the hiking or camping trip is over, its then time to clean the gear. One item that is often over looked is the water filter. If the water is left in the filter too long, bacteria will start growing in it. This will render the filter useless on the next hiking trip, because it will be full of bacteria.
Cleaning a filter is pretty much a straight forward operation. Get a large bowl of clean tap water, put some unscented bleach in with the water and wait a few minutes. Then use the water filter to pump the water from the bowl into the sink. Or, pump the water from one bowl to another, and then repeat. This way the bleach water is reused a couple of times.
Once the bleach water has been cycled through the filter, disassemble the filter and let it dry in open air. Let the filter, housing, hoses and pre-filter dry for a day or two. Then reassemble the unit and store until the next trip. Some people recommend cycling some bleach free water through the filter to remove as much of the bleach as possible, then disassemble and dry.
When the filter is used again, pump some water through the filter to help remove any left over bleach taste.