Top five methods for purifying water in the wild?

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Boiling Boiling is the most effective method for purifying water, killing 99.9% of bacteria, viruses, and protozoa with a single minute of rolling boil. Bring the water to a rolling boil for 1-3 minutes, depending on elevation and water source. Boiling is also effective against cryptosporidium and giardia, making it the preferred method for emergency situations.
Other Methods Other methods for purifying water include solar disinfection, sand filtration, and chemical disinfection. Solar disinfection involves leaving the water in a clear plastic bottle in direct sunlight for 6 hours, which can kill 99% of bacteria and viruses. Sand filtration can remove 99% of particulate matter, but is less effective against viruses and bacteria. Chemical disinfection with chlorine or iodine tablets can kill 99.9% of bacteria and viruses, but may not be as effective against cryptosporidium and giardia.
Charcoal Filtration Charcoal filtration is a simple and effective method for removing particulate matter and improving water taste. A standard water filter with charcoal can remove 99% of particulate matter, but may not be as effective against viruses and bacteria. A DIY charcoal filter can be made by stuffing a cloth or plastic bag with activated charcoal and tying it shut. The charcoal filter should be replaced every 6-12 months to ensure effectiveness.