Sand and charcoal’s a solid combo, but I always add a dose of unscented bleach after filtering and boiling—about 2 drops per liter, mix well, wait at least 30 min. Kinda a belt-and-suspenders approach, but redundancy is king when you can't afford to get sick. Solar stills work in theory, though they’re slow and not practical if you need a lot of water fast. I’ve also played with SODIS (solar disinfection) by filling clear PET bottles and leaving them in the sun for 6+ hours—effective, but only when there’s good sun and the water’s reasonably clear to start.
Chemical tabs are another backup in my kit, but I rotate them since they have a shelf life. For long-term, I'm actually messing around with a DIY ceramic filter made from terracotta flower pots—cheap, and they seem to remove a decent amount of nasties, though I always finish with boiling or bleach.
Anybody here tried making those bio-sand filters you see in off-grid village projects? Wondering about maintenance and possible clogging over time.
