A water filter is used to filter water from untreated sources on the trail while hiking and backpacking.Water filters provide different levels of protection using a micron measurement of how small of an organism they can filter. Most water filters are able to filter protozoa, bacteria, and cryptosporidium to varying degrees.
There are several common types styles of water filters. Pump water filters pump water through the filter with a hand activated handle. Gravity filters use gravity to push the water from a hanging “dirty” bag with untreated water through the filter into a “clean” water bag. Squeeze and sip filters enable the user to push the water through the filter using a “dirty” bag that has untreated water in it that is then pushed through the filter into the “clean” bag or by sipping the water directly from the water source through the filter. While some sip filters can only used by sipping the water, some squeeze filters can be used in line with a water reservoir in addition to being used in a sip or squeeze capacity.