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Safe drinking water is the one thing you can’t improvise on the trail. Streams that look clean can carry bacteria, protozoa and, in some places, viruses. The right treatment system depends on where you hike and how many people you’re carrying water for.
How we pick: this guide compares products using manufacturer specifications and published reviews. It is not based on our own hands-on testing. Prices and availability change, so check the current listing before you buy.
Quick picks
| System | Type | Best for |
|---|---|---|
| Sawyer Squeeze | Hollow-fibre filter | Light, versatile backpacking |
| Katadyn BeFree | Filter with soft flask | Fast flow, easy cleaning |
| LifeStraw Personal | Straw filter | Emergency kit and day hikes |
| Platypus GravityWorks | Gravity filter | Groups and base camps |
| Grayl GeoPress | Bottle purifier | Travel and areas with viruses |
Filter or purifier?
Filters remove bacteria and protozoa such as giardia and cryptosporidium. Most hollow-fibre filters use a pore size of 0.1 to 0.2 microns.
Purifiers also deal with viruses, either through chemistry, UV light or a purifier cartridge. In North America, viruses in wilderness water are rarely a concern, so a filter is usually enough. If you travel abroad, or hike near heavily used areas, choose a purifier or add chemical treatment.
What to look for
- Flow rate. Slow filters are frustrating when you’re thirsty. Gravity and squeeze filters are fast.
- Weight and size. Squeeze filters are tiny. Gravity systems weigh more but save effort.
- Cleaning. Hollow-fibre filters clog over time, so look for one you can backflush.
- Freezing. Never let a hollow-fibre filter freeze, because ice can crack the fibres and you can’t see the damage. Sleep with it in winter.
- Lifespan. Check the rated volume and replacement cost.
Our picks
Sawyer Squeeze
Best for: lightweight backpacking.
A tiny, light filter with a 0.1 micron hollow-fibre membrane. You can squeeze water through it, screw it onto a bottle or use it inline in a hydration system.
- Very light
- Backflushable
- Must never freeze
Katadyn BeFree
Best for: quick refills and easy cleaning.
A 0.1 micron filter that screws onto a collapsible flask. You scoop water, squeeze and drink. Rinsing the filter in clean water brings back the flow.
- Fast flow
- Soft flask packs small
- Flask can be fiddly to fill in shallow water
LifeStraw Personal
Best for: emergency kits and day hikes.
A simple straw filter that fits in a pocket. You drink straight from the source. It is not intended for carrying water back to camp.
- Cheap and compact
- No moving parts
- You have to lie down at the stream to drink
Platypus GravityWorks
Best for: groups and base camps.
Fill the dirty reservoir, hang it up and gravity delivers clean water to the second bag. It does the work while you set up camp.
- Good for several people
- Little effort
- Heavier and bulkier than squeeze filters
Grayl GeoPress
Best for: international travel and areas where viruses are a risk.
A bottle you fill, then press the inner cup down through a purifier cartridge. It is designed to remove viruses as well as bacteria and protozoa.
- Purifier, not just a filter
- Quick to use
- Heavier and costs more than a squeeze filter
Frequently asked questions
Is it safe to drink from a clear stream? Not necessarily. Clear water can carry microscopic pathogens. Treat it.
Do I need chemical tablets as well? They make a good backup in case your filter fails or freezes.
