Water Filters & Purifiers

We tested these so you don’t have to.

// Dina Mishev

PLATYPUS GRAVITY WORKS

What is it 
Fill the 4-liter “dirty” bag of this gravity-fed water-filter kit, connect it to the high-flow filter and “clean” bag, hang it so gravity can do its thing, and walk away. Within minutes, you’ll have filtered water.
Strengths 
No pumping or squeezing required; the bags can be converted to a solar shower.
Weaknesses 
This doesn’t kill viruses, and it can be difficult to fill the bag in shallow water sources.
Best for 
Effortless water filter for small groups.
Details 
$135; available at REI, 974 W. Broadway Ave., and rei.com

MSR GUARDIAN PURIFIER

What is it 
A pump purifier capable of treating 2.5 liters per minute with a hollow-fiber cartridge that is good for more than 10,000 liters of water.
Strengths 
Meets the testing standard used by the U.S. military for removal of viruses, bacteria, protozoa, and sediment from “worst-case” water conditions; the pump is self-cleaning so no backflushing or filter scrubbing is ever required.
Weaknesses 
While this pump is faster and easier than other pumps, pumping is still more work than gravity, UV, or straw filters; the price.
Best for 
Users who don’t mind the size (about as big as a 16-ounce water bottle) and weight (1 lb., 1.3 oz) since they come with ultimate filtration and durability.
Details 
$390; available at backcountry.com

SAWYER MINI WATER FILTER

What is it 
A filter that attaches to a water bottle, straw, or, for the lightest-weight option, an included soft-sided pouch. Fill your chosen vessel with dirty water and then squeeze or suck the water through the filter, and it’ll be 99.99999 percent free of bacteria and protozoa.
Strengths 
This filter fits in the palm of your hand and, with the 16-fluid-ounce collapsible Mylar foil pouch it comes with, weighs only 2 ounces. 
Weaknesses 
We’re still looking for one.
Best for 
Adventurers looking for an affordable, lightweight, easy-to-use filter.
Details 
$30; available at moosejaw.com

EDDY + FILTERED BY LIFESTRAW

What is it 
This 32-ounce stainless steel water bottle has a lid with a built-in LifeStraw hollow-fiber filter, which, through two stages of filtration, removes bacteria, parasites, and microplastics.
Strengths 
Fill the bottle with questionable water, screw the LifeStraw lid on, and start sucking through the straw filter—about as easy as filtering water can be.
Weaknesses 
Hard sided and weighing 1 pound, 1 ounce, this isn’t for devotees of fast-and-light backcountry travel.
Best for 
Stylish hydrating on the go.
Details 
$70; available at Teton Mountaineering, 170 N. Cache St., camelbak.com

KATADYNSTERIPEN ULTRA 

What is it  
A rechargeable purifier that uses ultraviolet light to scramble the DNA of living organisms in water so that they can no longer reproduce and make you sick. 
Strengths 
Easy to use: insert the UV light into your water bottle, press a button, and gently swirl the light around for 60 seconds (.5 liter) or 90 seconds
(1 liter).
Weaknesses 
UV disinfection deactivates living organisms—virses, spores, cysts, bacteria—but doesn’t remove particles. Also, if it breaks while you’re in the backcountry, you’re hosed.
Best for 
Areas where the water doesn’t have sediment or particulates and in which you’re carrying purification tablets, just in case.
Details 
$130; available at REI, 974 W. Broadway Ave., and rei.com

KATADYN MICROPUR MP1 WATER PURIFICATION TABLETS 

What is it 
Chlorine dioxide tablets that kill bacteria, viruses, and cryptosporidium—a parasite that causes a diarrheal disease you definitely don’t want to get.
Strengths 
These are lightweight and extremely packable, can’t break, and can treat all quantities of water. (1 tablet does 1 liter)
Weaknesses 
It takes 4 hours for the tablet to work its magic. Also, these tablets leave water with a chemical taste. (The Aquatabs brand of tablets have less of this taste, but Aquatabs don’t kill crypto.)
Best for 
Back-up. We always have these in our backpack in case something happens to our main purification/filter. 
Details 
From $11.95 for 20 tablets; available at outdoor shops around the valley JH