Every go-bag and RV emergency kit needs a way to make water drinkable. The question is which kind of filter. Here are the four common types, what each is good at, and what we'd pack.
Do emergency water filter straws work?
Yes, for what they're designed to do. A straw with a fine hollow-fiber membrane removes bacteria and parasites as you drink. The CDC's guidance is that a pore size of 0.3 micron or smaller removes bacteria and parasites. It also says what no portable filter does: remove viruses. And no filter makes chemically contaminated water safe. So the practical kit is a filter plus disinfection tablets, and a different water source if you suspect fuel or chemicals.
The four types compared
| Type | Examples we stock | Best for | Trade-offs |
|---|---|---|---|
| Filter straw | Purewell 5-Stage, Waterdrop straw | Lightest go-bag backup; one per person | Drink only at the source; can't fill a bottle or pot |
| Squeeze / inline filter | Sawyer Mini SP128, Sawyer Squeeze SP129 | Filling bottles and cooking pots; very flexible | Squeezing takes effort; needs backwashing |
| Filter bottle | Katadyn BeFree 1L | Hikes from camp; fill, drink, collapse flat | Small volume per fill |
| Gravity bag | Waterdrop 1.5 gal, Membrane Solutions 6L | Water for a group or a family at camp, hands-free | Bulkier; needs somewhere to hang |
What we'd pack
- Each person's go-bag: a filter straw. The Purewell and Waterdrop straws both include a carbon stage for taste.
- The rig's emergency kit: a Sawyer Squeeze or Mini, so you can fill bottles and pots. The Mini threads onto standard 28 mm bottles.
- Staying put for days: a gravity bag, so the whole group gets water without anyone squeezing.
- Always: Aquatabs to cover viruses. The 49 mg tablets treat a bottle; the 397 mg tablets treat larger containers.
Keeping a stored filter ready
- Dry it before storing. A damp filter in a sealed bag can grow mildew.
- Keep it from freezing once it's wet. Ice can crack hollow-fiber membranes, and Sawyer says to replace a filter you think has frozen.
- Know its capacity. Check the rating on each filter's packaging and note it in your kit list.
Bottom line
No single filter covers everything. A straw per person, one squeeze filter for the rig, and a strip of tablets is a light, cheap setup that handles most emergencies. Add a gravity bag if you camp with a group.
More: Purewell straw review · Purewell vs LifeStraw · Camp tools and survival gear