The 7 best backpacking water filters

Access to clean drinking water is never a guarantee in the wilderness, which is why a good filter is essential on your outdoor adventure. To remove bacteria, parasites, and other contaminants, the best backpacking water filters have a micron size of 0.4 or less, and they come in a range of styles, from gravity filters to straws.

The effectiveness of a portable water filter depends on the size of the pores in the filter itself, which is measured in microns. One micron is equivalent to 1/1,000 of a millimeter, and filters with smaller micron measurements will be able to filter out smaller particulates. Pores with a micron size of 1 or less can filter parasitic larvae, eggs, and protozoa, while a micron size of 0.4 or less will remove bacteria.

While water-borne viruses aren't typically a concern in North America, they're an important consideration when backpacking in developing countries. In those cases, it's best to opt for a water purifier (or use purifying tablets in addition to a filter) that eradicates viruses in addition to bacteria and protozoa.

With that said, the best lightweight hiking water filters come in a variety of styles —here's what to know:

Beyond filters, you'll find two water-purification options on this list that can eliminate viruses, as well as bacteria and protozoa: chlorine dioxide tablets that dissolve in water, and a two-in-one purifying and filtering bottle. So whether you're drinking from lakes, rivers, or streams on your journey, these are the best backpacking water filters to keep you safely hydrated.

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Katadyn's gravity filter comes equipped with a 3-liter bag, and has a hook near the fill hole that makes it easy to submerge in water and carry back to your campsite. Once the bag has been filled and the twist-on membrane filter has been attached, simply invert the bag and hang it from a tree branch or any elevated object using the adjustable straps.

Gravity pulls water through the membrane at a rate of about 2 liters per minute (or 67 ounces), and contaminants as small as 0.1 micron are removed. You can either drink the filtered water directly from the mouthpiece at the end of the filter hose, or use it as a spigot to fill water bottles, pots for cooking, or to wash hands. The flexible, collapsible pack folds flat for easy packing and weighs just 0.4 pound, making this a relatively lightweight option given the amount of water it can handle.

One reviewer wrote: "When I am backpacking I prefer to camp far away from water sources, to avoid big overnight temperature drops, condensation, bugs, animals searching for water, and noisy campsites. With this reservoir and integrated filter I always have enough water for overnight camping to cook supper, breakfast and all other camp needs."

One of the best inexpensive backpacking water filters out there, the LifeStraw is simple and popular, boasting a near-perfect 4.8-star overall rating on Amazon after 73,000 reviews. The tube straw has a built-in membrane micro-filter below the mouthpiece, which allows you to insert the filter directly into a water source or filled water bottle and use suction to force the water up through the 0.2-micron filter and then directly into your mouth. It's easy and efficient, but keep in mind that drinking can be a bit slow as the water needs time to move through the filter.

To clean this filter, simply blow on the mouthpiece to eject dirt, debris, and microscopic bacteria. Weighing only 1.6 ounces, the LifeStraw takes up minimal space in your pack, and comes with a lanyard, so you can wear it around your neck and keep track of it while hiking.

One reviewer wrote: "Very good tool to have in your backpack. We hiked 10 miles to a glacier and ran out of water in our backpacks. Filled an empty water bottle with glacier water and drank from the straw. Made it back to base camp with no problems."

Rather than using gravity or suction, this filtration system from Sawyer forces water through a fiber filter membrane when you squeeze the pouch. It removes bacteria and contaminants as small as 0.1 micron and comes with two flat collapsible 32-ounce pouches that screw onto the base of the filters when filled. You can either drink directly from the end of the filter by squeezing it into your mouth, or simply squeeze it into an empty water bottle. Weighing just 2 ounces, the Sawyer can fill a standard 16 ounce bottle with clean water in as little as 20 seconds, and it comes with a high-pressure syringe that allows you to backwash or clean it, for optimal performance over time.

One reviewer wrote: "I had never had to filter water before but this was so easy to figure out and use! Not heavy or clunky to carry either. Great addition to the backpackers gear!"

If you want to take a full-size water bottle with you when backpacking, this option from LifeStraw is a great pick. The two-stage filter attaches to the bottom of the bottle's lid and removes particulates as small as 0.2 micron, and the bonus carbon filter improves the taste of water. Since the filter is essentially built into the drinking mechanism, filtering is relatively fast, but some reviewers mentioned that it takes a bit of time to suction the water through the straw.

The leakproof bottle is made from break-resistant and BPA-free Tritan and has a silicone mouthpiece. A ring loop and carabiner allow you to attach the bottle to a strap or waistband when hiking. It's available in 22-ounce and 1-liter (about 34 ounces) volumes, which weigh 7.7 and 8.6 ounces, respectively. While on the heavier side, this is still a reasonable choice if you're already planning to bring a water bottle.

One reviewer wrote: "Took this on a backpacking trip and while the rest of the group pumped and pumped I just filled the bottle and dipped away. Was super convenient and made life easy during those times I was too tired to pump and wanted a quick drink of water. And I didn't get sick so I guess it worked at filtering the water too."

If you’re looking for a lightweight, space-saving water filter, this collapsible 1-liter BeFree flask from Katadyn weighs just 2.3 ounces and has a packable, squeezable design that takes up minimal space in a bag or jacket pocket. The twist-on filtering membrane removes organisms and bacteria as small as 0.1 micron and can be cleaned between uses by shaking or swishing it in the flask or directly in your water source.

When you squeeze the flask, pressure from your hand forces water through the filter and out of the drinking nozzle at a rate similar to what you’d expect from a sports water bottle. The wide mouth of the flask makes filling easy, and the drink nozzle has a cover that keeps it out of contact with potentially contaminated water. It's similar to to the other squeeze filter on the list, but specifically designed for on-the-go sipping.

One reviewer wrote: "LOVE LOVE LOVE- any backpacker this is essential to keep in your bag. It filters so quickly and weighs next to nothing. We took two of these to hike Condrumn springs and our friends who had a different brand ended up using ours the whole time because it is so quick and efficient."

Katadyn's water filter pump uses two pistons to generate pressure to pump water through a two-stage filtration system that removes particles as small as 0.2 micron. The 36-inch input hose is placed directly into your water source, and the hand pump forces water through a ceramic pre-filter, a glass fiber filter, and a replaceable active charcoal core that improves water flavor and removes odors. The adapter base of the pump can be threaded into a water bottle, or attached to a hose for filling vessels or cooking equipment.

At 15 ounces, the Vario is the heaviest filter here, however it's the only one that offers two adjustable filtration modes: a long-life mode, which filters 1 quart of water per minute in visibly contaminated water, or a fast mode, which bypasses the ceramic filter and purifies 2 quarts of water per minute.

One reviewer wrote: "Excellent filter, even in longer life (slower flow) mode, it was over twice as fast and much easier to pump than a friend's MSR filter. One filter easily kept up with the hydration/cooking/cleaning needs of three people on a three-day backpacking trip. Screws directly onto the top of a standard Nalgene bottle."

If you're backpacking in a developing country, or anywhere else there's risk of water-borne viruses like rotavirus, norovirus, or hepatitis A, it's worth getting this purifying water bottle. It allows you to purify 24-ounces of water in just eight seconds by simply pressing down on the cartridge, and like the filter options on this list, it also removes dirt, bacteria, and protozoa.

Weighing 1.6 pounds when empty, the 24-ounce bottle can purify up to 65 gallons before the cartridge needs to be replaced (about 350 bottle fills). Last but not least, the company guarantees that your purified water will meet or exceed United States Environmental Protection Agency (EPA) standards for drinking water.

One reviewer wrote: "By far the easiest and most convenient water purification system I've ever used... Family and l just spent a month in Kenya, drank from all sorts of dubious and funky water sources with zero issues. Since it's so easy there was no inclination to procrastinate filtering water, so I was fully hydrated the entire time. Totally worth the price tag."

Similar to the previous option, these iodine water-purifying tablets also disinfect contaminated water from viruses, as well as bacteria and protozoa, making them suitable for use in developing countries. They're compact and lightweight, but it does take four hours to purify 1 liter of water, so you'll have to plan ahead when using them, and it's worth knowing that the water may take on a slightly metallic flavor.

While they can be used on their own, some reviewers have reported they simply keep these tabs on hand as a backup solution in case their water filter fails. Keep in mind, though, that they won't remove dirt and other debris, so this option may be best used in addition to a filter.

One reviewer wrote: "I used these on a long backpacking trip up in the Rocky Mountains. They worked great, I took water directly from several sources including a lake, stream, and pond. Fill up your bottle, drop in a tablet then wait a while and you'll have drinkable water."