My water filter clogged solid on day two of the Teton Crest Trail
I was filtering from a silty stream near Marion Lake and the ceramic element just stopped passing anything after maybe 20 liters. Ended up having to boil everything for the next 36 hours until I got to a ranger station. What's a better backup plan than just carrying iodine tabs?
Boiling everything for that long is a major hassle though, especially on a trail like that. A small backup filter or chemical drops are way less work in a pinch. It's worth the couple ounces to avoid cooking all your water.