best water filters for backpacking

Sawyer Squeeze

The hollow-fiber filter most "best backpacking filter" lists still start with. The 3 oz cartridge screws onto the two collapsible pouches in the box or onto any 28 mm threaded bottle, and the included tubing and adapters let you run it inline on a hydration hose or as a gravity setup instead. Sawyer rates it to 0.1 micron absolute and says the filter lasts up to 100,000 gallons, and it is meant to be backflushed with the included plunger rather than replaced. Worth knowing: the 3 oz figure is the filter alone, the full kit is 8.19 oz, and Sawyer publishes no flow rate for it.

Sawyer MINI

The cheapest way into hollow-fiber filtration: the same 0.1 micron media and the same 100,000 gallon rating as the full Squeeze, in a 2 oz body that costs about $29. It attaches to the included drinking pouch, a disposable 28 mm bottle, hydration-pack tubing or the included straw, so it adapts to almost any setup. The trade-off is filtering surface, which is smaller than the Squeeze's; Sawyer publishes no flow rate for either, so speed is the one thing you cannot compare on paper here.

Katadyn BeFree 1.0L

A one-litre collapsible flask with the filter built into the cap: fill it at the stream, screw the cap on, and drink from it or squeeze into a bottle. Katadyn rates it at up to 2 litres a minute, the joint-fastest here, and the EZ-Clean membrane is cleaned by shaking or swishing rather than backflushing with a syringe. Two caveats: its 1,000-litre rating is the shortest of any filter in this table, and Katadyn does not publish a US price on its own site, so the price here comes from a retail listing.

Platypus QuickDraw Filter

Platypus's answer to the Sawyer Squeeze, sold as a bare 2.4 oz filter you build a system around: dual inner/outer threads let it screw onto smartwater bottles, Platy bottles or its own reservoirs, and a ConnectCap turns it into a gravity or inline setup. It is the fastest filter in this table on paper at 3 litres a minute, and it is cleaned by shaking rather than with a syringe. The cartridge is rated to 1,000 litres, on the short side, and the bottle or reservoir it squeezes from is not included at this price.

LifeStraw Peak Series Collapsible Squeeze 1L

A complete one-litre kit rather than a bare filter: a collapsible squeeze bottle with a 0.2 micron membrane filter in the cap, usable as a bottle, a straw, or a squeeze source for another container. Its filter is rated to 2,000 litres, double the BeFree and QuickDraw, and it stops passing water when it reaches the end of its life instead of leaving you guessing. At 3.2 oz for the system it is heavier than a bare squeeze filter, and LifeStraw does not publish a flow rate.

LifeStraw Peak Series Straw

The cheapest and simplest thing here: a 2.3 oz straw you sip through directly from a lake or stream, or screw onto a standard bottle or a gravity hose. Its 0.2 micron membrane is rated to 4,000 litres, the longest life in this table, and the whole thing costs about $25. The limitation is that a straw filters only what you are drinking at that moment, so it does not fill bottles or a cook pot on its own, which is why it is usually a backup rather than a primary system.

LifeStraw Peak Series Gravity 3L

A three-litre dirty-water bag you hang from a branch and leave to filter itself at 1.7 litres a minute, which makes it the cheap way to stop squeezing for a pair or a small group. It weighs 8.1 oz with bag, hose and connectors, backflushes without tools, and shares the 2,000-litre Peak Series membrane. Unlike the Platypus GravityWorks it ships with one bag rather than a dirty-and-clean pair, so you still need a bottle or reservoir on the clean side.

Platypus GravityWorks 4.0L

The group system: two four-litre reservoirs, dirty and clean, joined by a hose and an inline microfilter, so you fill one bag, hang it, and come back to four litres of drinking water at 1.75 litres a minute. It weighs 11.5 oz complete and the cartridge is rated to 1,500 litres, with a four-second backflush to restore flow. It is the most expensive filter here short of the purifiers, and the bags and hose take more room in a pack than a squeeze filter, which is the price of not squeezing anything.

MSR TrailShot

A 5 oz pocket filter you work one-handed: drop the intake hose in a puddle or shallow creek and pump the bulb, and it fills a one-litre bottle in about a minute. That bulb is what sets it apart from squeeze filters, because it draws from water too shallow to dip a bottle in, and it needs no setup at all. The cartridge is rated to 2,000 litres and restores flow with a few shakes, but at 1 litre a minute it is slower than the squeeze filters and it costs more than most of them.

MSR MiniWorks EX

The old-school ceramic pump, and the one to pick when the water is silty or tastes bad: its carbon-and-ceramic element is the only media here rated against chemicals and toxins as well as bacteria and protozoa, and the ceramic can be scrubbed clean in the field with no tools. It screws straight onto a Nalgene and pumps a litre a minute. The cost is weight, a full pound, roughly five times a squeeze filter, which is why it shows up on canoe trips and long expeditions more than on ultralight kit lists.

MSR Guardian Purifier

The one built for water you would not otherwise drink. Its 0.02 micron hollow fibers are fine enough to remove viruses as well as bacteria and protozoa, it is tested to the NSF P248 military protocol, and it cleans itself on every stroke by diverting some filtered water back through the fibers, so it does not clog on silty sources. It pumps 2.5 litres a minute and the cartridge is rated past 10,000 litres. It is also a pound and a seventeenth and the most expensive item here by a wide margin, so it earns its place on international trips and in emergency kits rather than on a weekend hike.

Katadyn Hiker Pro

The pump a lot of scout troops and rental fleets still run: a pleated glass-fiber cartridge with an activated carbon core, pumped by hand at about a litre a minute, with quick-connect hoses and a bottle adapter in the box. The carbon core is there for taste, and the removable filter protector is meant to keep the cartridge going longer in dirty water. Its 300-gallon (1,150 litre) cartridge is the shortest-lived of the pumps here, and at 11 oz it weighs several times what a squeeze filter does.

Grayl UltraPress Purifier

A 16.9 oz bottle you fill with dirty water and then press, French-press style, in about ten seconds. The cartridge removes viruses along with bacteria and protozoa and also targets heavy metals, chemicals and taste, which makes it a travel purifier as much as a backcountry filter. There is no setup, no hose and nothing to squeeze, and the press works on silty water other filters clog on. The catches are capacity and cartridge life: half a litre per press, and only about 300 presses (150 litres) before a replacement cartridge, by far the shortest here.