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How to Treat Backcountry Water to Make it Safer


Going into the outdoors? Always start a trip with one or more full water bottles, and replenish your supply from tested public systems whenever you can.

On adventures of longer duration, streams, lakes, springs and snow are potential sources of water, but you must treat all drinking water in the wild, no matter how clear and clean it appears to be. Even clean-looking streams can be full of bacteria, protozoa and other nasty bugs that can cause serious illness.

Filter or purify that water first with one of these handy options.


This one is simple. Just heat any suspect water to a roiling boil. When half-inch-wide bubbles are rising from the bottom of the pot for about a minute, you’re good to go. Boiling is cheap, simple and very effective. But it can be slow, especially at high altitudes, can use lots of stove fuel and won’t remove silt.



Pump Filters clean the water by pushing it through a filter as you pump. They require hand pumping, which can be tiring, but they’re lightweight, durable and a good choice for backcountry hikers.

Traditional pump filters certainly still have their place in the backcountry, such as when dealing with silted water, or when speed is critical for treating a large amount of water either for a group or when water sources are far apart. The MSR HyperFlow Microfilter ($100, excels for its speed and packability. Measuring just 7-by-3.5 inches and lighter than many competitors, this filter cranks out 3 liters per minute, removing protozoa, bacteria and particulate matter (though not viruses or chemicals), and it leaves no taste. A Quick-Connect Bottle Adapter (included) lets you pump directly into a variety of containers.


Chemical tablets purify water with a chemical that kills off the bad stuff. They’re the lightest, most portable option, but can add a slight taste to the water.

The pocket-sized MSR TrailShot Microfilter ($50, redefines the pump filter. Nearly as compact as the BeFree, this hand pump cranks out a liter in a minute and fits in a side pocket of a daypack. Just place the input end of the hose in any fairly clear water source, and either drink directly from the filter’s spout or pump water into a bottle or bladder. It’s ideal for one or two people on a fast-paced outing where time efficiency and minimizing weight are top priorities, like an adventure race or ultralight backpacking (preferably where water sources are frequent). MSR projects its life at up to 2,000 liters.


UV light purifies water using ultraviolet light that kills the bad stuff. Quick and easy, it is best for individual use, but it does require batteries.

Once hailed by Time magazine as the best invention of 2001, the easy, simple and fast Steripen Classic 3 ($80, uses ultraviolet light to destroy bacteria, works in a wide range of temperatures and is good for about 8,000 treatments. It can use four AA alkaline batteries (which will purify 50 liters of water) or four lithium batteries (which will purify 150 liters). The Classic 3 comes with a pre-filter to use in clouded or silted water. Drawback: It treats only 1 liter at a time, so it’s practical for only one or two people.


Gravity filters use gravity to move water through the filter. No hand pumping is needed, and it’s a great way to easily filter a lot of water for a group.

Single-person bottle filters don’t get lighter or more compact than the collapsible Katadyn BeFree Water Filtration System 0.6L bottle ($40, A mere 9-by-3-by-3 inches and weighing just 2 ounces, it delivers a strong stream of water and filters up to 2 liters per minute just by squeezing the soft-sided BPA-free flask. It will even pour through the mouthpiece when you flip it upside down. Its microfilter keeps out harmful bacteria and has a projected life of 1,000 liters. There’s also the larger BeFree Water Filtration System 1L ($45), BeFree Water Filtration System 3L ($60) and ultra-convenient Gravity BeFree Water Filtration System 3L ($70,


Straw filters clean the water automatically as you drink it through a straw-like filter. Best for solo use; obviously not a good choice for groups.

LifeStraw Go ($45,, a water bottle with two stages of filtration, removes virtually all bacteria and chemicals, and reduces bad taste and odors. Beyond its quick convenience, the hard-sided 22-ounce bottle has an advantage over soft bottles in that you can fill it from still water (think: lake), whereas soft-sided bottles require running water (think: creek), because they’ll collapse if dipped into calm water.


A good rule: 2 to 3 liters of water per Scout per day. Don’t wait until you’re thirsty to drink. Always have it at the ready and drink small amounts frequently.


Muddy water? No problem. Just let it settle in the bottom of a wide pot. Then very carefully scoop the clear water from the top. Next, strain it through a bandana or a paper coffee filter. Finally, filter, boil or purify and drink up!



WATER FILTERS use microscopic pores to strain out nasty stuff like bacteria from water sources. For most backcountry trips in the U.S., you don’t need more than a filter.

PRE-FILTERS are used to remove large, visible particles before you start the filtering process — particularly important in cloudy water.

WATER PURIFIERS eliminate bacteria, too, but also use chemicals or ultraviolet light to kill viruses, which are too tiny for most filters to remove. Purifiers become more necessary in the deep backcountry or while traveling to some other countries.

11 Comments on How to Treat Backcountry Water to Make it Safer

  1. the unexplained question // June 18, 2020 at 3:31 pm // Reply

    yeah.. i think that’s how to filter water but it said that it purifise some type of viruses so does it purify the covid-19 and animal liquid/urine/pee

    date: 6/18/2020 4:31 PM

  2. my favorite filter is the Life Straw the reason It Is my favirite filter is that it is easiest method I have used compared with having to make a fire and bowiling the water a

  3. Prometheus // August 8, 2019 at 5:01 am // Reply

    Odd that the single most common filter seen on the trail, the Sawyer Squeeze series, is not mentioned.

    Also, the UV option works best if you filter the water first. The water has to be clear for it to work.

  4. Boil it!

  5. We use the Vario by Katadyn. Works great and attaches right to your bottle top eliminating rim contamination. The prefilter allows the main filter to last times longer than most other brands too.

  6. I agree with the boil it group.

    • Knife Xpert 157 (aka Chad 101) // February 10, 2014 at 11:08 am // Reply

      Are you really going to take the time on a hike to stop, build a fire or light a stove, boil water, wait for it to cool, and then get going again? lets see… by now you have wasted about 1-2 hours. just buy Potable Aqua taps and use those. But make sure to get the iodine neutralizers. iodine pills are a lot faster then boiling. and plus who wants to drink warm water? And if you dont like using the taps, then just bite the bullet and fork over the cash to get a good filter. Its way worth the money.

    • When I was in the military most servicemen carried the MSR Miox purifier. It made both a brine and an electric charge to the water; a double control treatment. It lasted a full tour with one kit and 2 AA batteries. If you want a true tested item, here’s one.

  7. First Need is the only way to go no matter where your going or what conditions you will run into in any country. Very professional results (no viruses) not just for filtering fairly clean streams in the backcountry. The only possible draw-back is that you must keep the unit from freezing.

  8. Just back from a Boundary Waters Wilderness canoe trek; and again the Steri-Pen was a champion. it worked quickly and effortlessly for everyone in the group (7 scouts). We did boil our base camp water but individual bottle use by the scouts was covered by “The Pen.” We had our Katadyn Guide pump with but it never saw day light; water was super clear, even before using a coffee filter as a pre-filter. Only spent $7.00 on batteries for the entire trek, that’s thrifty.

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