photo of Thousand Island Lake and Banner Peak, John Muir Wilderness, CA

  Water Filter Reviews

Banner Peak & Thousand Island Lake

Most Popular Backpacking
Water Filters and Purifiers

Water Filters

  • Sawyer Squeeze Filtration System
    • Squeeze raw water from Mylar pouch through filter into your water bottle
    • Can be used with other pouches with matching threads.
    • Removes 99.9999% or more of all bacteria and protozoa, including giardia
    • Lightweight syringe to backflush filter
  • MSR MiniWorks Microfilter
    • Filter cylinder screw onto standard wide-mouth water bottles
    • Hand pump draw water from intake tube
    • Capable of pumping one liter per minute
    • Filter pore size 0.2 microns, effective against bacteria, protozoa, chemicals/toxins, and particulate
  • Katadyn BeFree
    • Filter fits on custom 0.6 liter soft water bottle mouth
    • Users gently squeeze supple bottle as they drink
    • Effective against microorganisms

Gravity Flow Filters

  • MSR AutoFlow
    • Hang 4-liter reservoir from tree and place water bottle below.
    • The filter removes protozoa and bacteria at a rate of 1.75 liters per minute
    • Best for in-camp use by a group
    • Filter removes contaminates 0.2 microns and larger
  • Platypus GravityWorks
    • 4-liter reservoir hangs from tree and flows through filter by gravity into a receiving reservoir.
    • The 4 liters are filtered in about 5 minutes
    • Filter protects against bacteria and protozoa (Giardia)

Water Purifiers


SteriPEN Adventurer  

  • SteriPEN Adventurer
    • Uses Ultraviolet light to destroy bacteria and protozoan cysts (such as Giardia) in water
    • Simply activate the lamp and stir it in a water bottle for about 90 seconds until the light goes out
    • Uses two CR123 batteries; does not work well in freezing temperatures
    • Doubles as emergency flashlight
  • Potable Aqua & Aquamira Tablets
    • Drop Chlorine Dioxide tablet into water bottle and allow to sit for 4 hours for full effectiveness
    • Effective against viruses, bacteria, and cysts such as Giardia and Cryptosporidium.
    • Carried by many as a backup to other systems
    • Read cautions of dangers of mishandling the tablets

In recent decades backpackers have heeded the warning that water in Sierra streams and lakes may not be safe to drink without first filtering or purifying it. Antidotal accounts of serious bouts of Giardia have convinced many that it is not worth the risk to drink untreated water. On the other hand, other backpackers report drinking stream water regularly without any ill effects.

Gsrcia Bear Canister

Sawyer Squeeze Filter  

With lightweight filter and treatment systems available, it just doesn't seem worth the risk to drink untreated water. At times it can be an inconvenience, but the peace of mind knowing that the water is safe to consume is worth the time it takes to filter water.

Most commonly cited is the danger of Giardia. Studies have shown that the frequency of Giardia in Sierra streams is low, but the long-lasting symptoms of Giardiasis have caused many to want to avoid any risk of ingesting it. Another concern is about bacteria such as E-coli, which, although rare in Sierra waters, can be found most often in areas where cattle have grazed.

Boiling Water

The CDC tells us that boiling water for 1 minute (or 3 minutes above 6,562 feet (2000 meters)) should kill all pathogens, so there is rarely a need to filter cooking water.

Water Filters
Product Weight Filter Speed1 Price2
1Filtering speeds based on manufacturers' information
2 Prices can vary depending on vendor
Sawyer Squeeze Filter 3.5 oz. about
1 liter/min
MSR MiniWorks 16 oz. up to 1 liter/min $65
Katadyn BeFree 2.3 oz. 1.9 liters/min $36.50
MSR AutoFlow 10.5 oz. 1.75 liters/min $120
Platypus GravityWorks 10.75 oz. 0.9 liters/min. $120
SteriPEN Adventurer 3.8 oz. 1 liter/90 secs $45
Potable Aqua Water Tablets 0.9 oz. 1 liter
4 hours
$15/30 tablets
Aquamira Water Tablets 0.9 oz. 1 liter
4 hours
$21/50 tablets

Related Articles

A Guide to Drinking Water Treatment and Sanitation for Backcountry & Travel Use, Centers for Disease Control

Giardia Lamblia and Giardiasis With Particular Attention to the Sierra Nevada, Robert L. Rockwell, January 2002

            Pros and Cons of Water Filter and Treatment Systems

Water Filters

Hand-held, pump filters, such as the MSR MiniWorks, were very popular for years. Their main drawbacks are their weight and bulk along with the effort required to pump-filter the water. The use of the intake tube can be helpful in situations where access to the water source is difficult.

More recently the Sawyer Squeeze Filtration System has gained popularity. Forcing water from the Mylar pouch through the filter by squeezing is somewhat easier than pumping. But the big advantage is the much reduced bulk and weight of the system. While the Mylar bags are prone to developing leaks, Platypus Softbottles work just as well in place of the Mylar bags.

The Katadyn BeFree Filtration System is intended as an on-demand filter attached to their 0.6 liter collapsible flask. The collapsible flask takes up almost no space when empty. Its wide mouth makes for quicker filling than the Sawyer pouches. However, many backpackers wish there were a slightly larger size flask. The Hydrapak Seeker water bottles fit the BeFree filter.

Gravity Fed Water Filters

The MSR AutoFlow is a convenient water filtering system for in-camp use. For groups of 3 or more or for basecamps, it makes sense to carry a system like this that won't send you repeatedly to the stream to filter a fresh supply.

The Platypus GravityWorks is similar to the MSR AutoFlow. GravityWorks main difference is that it comes with a 4 liter reservoir for collecting the clean water as it filters.

Water Purification Systems

The SteriPEN uses ultraviolet light to render organisms in the water harmless. Simply stir the lighted pen in a wide-mouth bottle with a liter of water for about 90 seconds until the light goes out. No pumping or squeezing.

Some users have found the SteriPENS temperamental. Carrying a backup water purifying system (such as purifying tablets) is wise. Treated water should not be left in direct sunlight for long periods of time.

Water purifying tablets such as Aquamira and Potable Aqua are lightweight, but for the tablets to be fully effective, treated water should not be consumed until after 4 hours. Most hikers carry the tablets as an emergency backup.