While researching the safest methods for harvesting water, I found these tips. If making a purchasing for your next trip, be sure to see #9, the Center for Disease Control’s (CDC) table comparing the effectiveness of water disinfection methods.
2. “Except for boiling, few of the water treatment methods are 100% effective in removing all pathogens.” CDC, A Guide to Drinking Water Treatment and Sanitation for Backcountry & Travel Use
3. “Water that has been disinfected with iodine is NOT recommended for pregnant women, people with thyroid problems, those with known hypersensitivity to iodine, or continuous use for more than a few weeks at a time.” CDC, A Guide to Drinking Water Treatment and Sanitation for Backcountry & Travel Use
4. “Filter pore size is the primary determinant of a filter’s effectiveness…Microfilters with “absolute” pore sizes of 0.1–0.4 µm are usually effective to remove cysts and bacteria but may not adequately remove viruses, which are a major concern in water with high levels of fecal contamination” CDC, Water Disinfection for Travelers
5. “Avoid drinking untreated water shortly after a heavy rain, when streams are ‘on the rise.’ Major rainfall events can cause overland and ephemeral flow that will transport material from most of the surface of the watershed into receiving streams and other water bodies. After such events it’s common that bacterial loads can increase in concentration by several orders of magnitude.” REI, Backcountry Water: What Are the Risks?
6. “Be diligent to maintain good personal hygiene when in the wild. Health complications often believed to be caused by ingesting contaminated wilderness water are usually the result of poor sanitation practices, particularly dirty hands.” REI, Backcountry Water: What Are the Risks?
7. “At higher elevations, where the boiling point of water is lower, boil for several minutes.” USDA Food Safety and Inspection Service, Food Safety While Hiking, Camping & Boating
8. “Extensive data show that UV light can kill bacteria, viruses, and Cryptosporidium oocysts in water. The effect depends on UV dose and exposure time, and requires clear water because suspended particles can shield microorganisms from UV rays. These units have limited effectiveness in water with high levels of suspended solids and turbidity….Portable battery-operated units that deliver a metered, timed dose of UV may be an effective way to disinfect small quantities of clear water in the field; however, more testing is needed for conclusive evidence.” CDC, Water Disinfection for Travelers
9. The CDC compares water disinfection techniques:
Original table in Water Disinfection for Travelers
Photo: taken while hiking in Killarney National Park, Ireland