Filtered water
Overview
Filtered water is water that has been passed through a physical filtration device to remove sediment, protozoa, and bacteria. It is a primary method of water treatment on long-distance trails.
Key points
- Removes sediment, protozoa, and most bacteria depending on filter pore size.
- Does not remove viruses unless paired with other treatments.
- Flow rate decreases as filters clog and require backflushing.
- Compatible with squeeze systems, pump filters, and gravity setups.
- Essential in environments with unclear or variable water quality.
- Often paired with chemical treatments for additional protection.
Details
Filtered water is obtained by pushing or pulling untreated water through a membrane filter designed to trap harmful microorganisms and debris. Most backpacking filters use pore sizes between 0.1 and 0.2 microns, effective for removing protozoa such as Giardia and Cryptosporidium and many bacteria.
Filters come in various configurations, including squeeze-style units, gravity-fed systems, and pump mechanisms. Over time, sediment and organic material reduce flow rate, requiring backflushing or cleaning to restore performance.
Filtering alone does not reliably remove viruses or chemical contaminants, though these risks are low in many backcountry settings. Some hikers combine filtration with chemical treatments or UV purification for comprehensive protection.
Filtered water is a cornerstone of hydration strategy in areas where water sources may be murky, slow-moving, or downstream of heavy use.
Related topics
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