We sell water filters, so read this knowing that. It's also the page we wish every filter brand published.
Hollow-fiber membranes (straws, squeeze filters, gravity elements)
Remove: bacteria (E. coli, salmonella) and protozoa (giardia, cryptosporidium) — the germs that make North American fresh water dangerous.
Don't remove: viruses (too small), dissolved chemicals, salt, or heavy metals. No portable filter of this class does — and a brand that claims otherwise without a lab sheet is selling a story.
Activated carbon
Improves: taste and odor; reduces chlorine.
Doesn't: kill germs on its own. That's why serious systems pair carbon with a membrane or another kill step.
Purification tablets
Kill: most germs, given time — follow the packet exactly.
Don't: remove sediment or improve taste. Best as the backup layer in a go-bag.
Boiling
Kills: everything biological — one minute at a rolling boil (three above 6,500 ft). The gold standard.
Doesn't: remove chemicals, and it costs fuel and time.
The honest setup for a family
Layer them: a personal straw per person for the go-bags, a gravity system on the counter for the household, tablets as backup, and the bleach recipe (8 drops per gallon, 30 minutes) written down. The free Family Water Plan covers when to use which — because knowing the limits of your gear is what being ready actually means.