Boiling is still the most reliable option as long as you can get a good rolling boil for at least a minute (longer if you're at higher elevations). That's what we relied on back when storms took out our power for a week, and nobody got sick. Solar disinfection (the SODIS method) does work, but it needs very clear water and strong sunlight for 6+ hours, so it's only practical in certain climates and seasons. Tried it during a camping trip once and the taste was fine, but I always felt better boiling if I had the means—it’s just more foolproof.
Homemade sand/charcoal filters are decent for getting rid of particles and some nasty tastes, but they don’t kill bacteria or viruses. Think of those as pre-filters before you disinfect. If you can combine a homemade filter with boiling, that’s a good combo.
Curious if anyone’s managed to build a gravity drip filter that really works for daily use? I’ve looked into big bucket systems with sand and charcoal, but I wonder about the upkeep, especially keeping mold or slime
