Drinking Water Treatment Tablets

These are small, light, and cheap, which is exactly why they belong in every 72-hour kit and glove box. One bottle holds 50 tablets for treating water when you're away from home and away from your filter.

I keep tablets myself, a different brand. They aren't a replacement for a good filter at home. They're the backup for when you're on the road, evacuating, or your filter is somewhere you aren't.