Up until now, adventure travelers heading to places where water is questionable had few choices: bring a UV-light-equipped sterilizing pen, a hand-pump filter that takes time and energy or chlorine- or iodine-based tablets that purify but take at least 30 minutes to work. Now, water bottle companies have gotten smart and are equipping bottles themselves with these technologies, conveniently combining drinking vessels and purifiers into one neat bundle. It’s time to ditch the single-use plastic water bottle for good.
Before packing for your next trip, search the Centers for Disease Control and Protection. Select whatever country you are visiting for specifics on contamination. For example, hepatitis A is a virus found in contaminated water in many countries in the developing world, but with specific water purifying systems (not just filtering), that virus can be removed. Do you need to protect just from bacteria or also from viruses? Some systems filter to remove protozoa (such as giardia), bacteria (e-coli, salmonella, cholera) and chemicals or pesticides; some systems filter and purify, which then eliminates viruses, like hepatitis A and rotavirus. Remember, many water systems filter out the chunky stuff like pebbles and grit, but not all purify against bacteria and viruses.
We tested six water bottles and their purifying systems in the backcountry to find out which we trusted most, how easy it was to filter, what the drinking experience was like, durability and, well, style points. Here are our favorites.
Purifiers + Filtering Systems
What these do: Guard against bacteria, protozoa, viruses, chemicals, heavy metals and other pollutants. Also, filter out gunk and odor.
Best for: Central and South America, Africa, most of Asia and parts of Europe
Grayl Geopress
The Grayl Geopress is a do-it-all, versatile water purifier and filtration system in one, and the easiest to use and drink from of all the bottles we tested. It both filters and purifies with a cartridge at the bottom of the bottle to remove 99.99 percent of viruses, bacteria and protozoan cysts (which can cause infections), as well as filtering particulates, many chemicals, and heavy metals — all of which can make you sick.
Using the water bottle was easy — it works like a French Press where you press down on the inner container so the water from the outer container gets pushed through the purifying and filtering cartridge into a separate internal vessel. This took us eight seconds. Once it takes about 25 seconds (around 350 uses), it’s time for a new filter. We found we had to use our whole body weight to press down the system, but that wasn’t a big issue. In fact, the press system easier to sip from than those that use a filtering straw. The clean water came out tasting slightly better and was less foggy than the original source. We liked the large carrying handle for holding or clipping onto our pack with a carabiner and the grippy bottom.
Volume: 24 ounces
Tech specs: electroadsorption (ion exchange, ultra-powdered activated carbon and silver treated zeolites)
Weight/size: 15.9 ounces; 10.4 inches high with a 3.4-inch diameter
Sawyer Select Filter S2 and S3
The S2 and S3 Sawyer Select Filters are take some getting used to. The soft silicone bottle uses a foam membrane combined with a hollow fiber filter at the top. Squeeze the full bottle for ten seconds to move the water through the system and then you can drink. Filling the bottle, though, took longer than we wanted, as the water has to soak into the foam membrane. From there, the flow of the water from the bottle to mouth was painfully slow, though you could squeeze the water into another vessel fairly easily. Overall, the entire system was cumbersome to both drink and pack, at about a little over a foot long (they recommend not storing it compressed). The S2 system will last for 800 uses and removes viruses, bacteria, protozoa, chemicals, pesticides and general gunk while the S3 system offers 400 uses and removes everything above plus heavy metals.
Volume: 20 ounces
Tech specs: Foam Adsorption Technology (a dense, large foam membrane with activated carbon) combined with a hollow fiber filter
Weight/size: 10 ounces; 14 inches
Epic Water Filters, The Answer | Nalgene
The best part about the filter from Epic Water Filters is that you can use it with a water bottle you already have, like a Nalgene or a Hydro Flask. You just have to buy the right filter for the water bottle you own. In The Outdoor Answer Kit for Nalgene, you get a filter and straw, plus two lids (one easy-flip sports lid and one locking, dust-cover lid with a button) that fits a wide mouth, 32-ounce Nalgene bottle. Once you fill your water bottle up, place the straw-and-filter lid back on and drink from there. This system did take some muscle to get the water flowing through the filter and straw, unlike the Grayl. The outdoor filter uses nanofibers and electroabsorption to help remove 99.99 percent of viruses, bacteria, giardia, cryptosporidium, as well as lead, chlorine, arsenic and other heavy metals or pollutants. Epic Water Filters also has a filter specifically for urban settings with tap water, which filters heavy metals and pollutants, but not viruses and bacteria. The average filter life is three to four months.
Volume: 32 ounces
Tech specs: activated carbon coconut filter
Filter Only
What these do: filter against protozoa and bacteria, but won’t help purify water against viruses.
Best for: outdoors in North America, general tap water in the U.S. and other non-developing countries and any place where the water is safe to drink, but might be smelly or cloudy
Katadyn BeFree
Extremely lightweight (just two ounces), the Katadyn BeFree is made from a collapsible material, so it can be rolled up to a tiny size. And, it’s extremely easy to use. Unscrew, fill with water and then drink the water through the EZ-Clean Membrane hollow fiber filter and sports cap. Drinking water through this filter isn’t as difficult as others because you can squeeze the water bottle to move the water through the filter (or squeeze the water directly into another vessel for cooking and cleaning). The EZ-Clean Membrane filter is effective against microorganisms such as bacteria, protozoa, and sediment, but does not protect against viruses.
One benefit of this filter is that it is easy to clean. You simply swish the filter in water or shake the bottle to remove any build-up and debris, unlike the LifeStraw and Sawyer, which need the backwashing syringe for cleaning. This system is perfect for for a quick filter before boiling water for camp cooking. Without a carbon filter to help with taste and odor, water from the BeFree was clean and clear, but still tasted slightly off when drinking from a stream or lake.
Volume: .6 liters, 1 and 3 liter bladders
Tech specs: Hollow fiber filter 0.1 micron
Weight/size: 2 ounces, 10 inches by 3 inches
WaterWell Foldable Squeeze Travel Water Bottle
The Foldable Squeeze Travel Water Bottle filters out 99.9 percent of bacteria, parasites and cysts (not viruses). The filter, which can be replaced, uses a two-stage ultrafiltration system in the straw, which is good for up to 1000 liters of water and is easy to sip through with a good flow of water. Plus, the flexible walls make it easy to squeeze filtered water out into another bottle. With the travel system, you get two squeeze bags for extra carrying capacity and a protective soft outside cover to reduce punctures. The attached cap seems slightly flimsy, and if it breaks, you’ll be stuck with a cap-less water bottle. But, we did like that the water tasted better than competitors’ due to the activated carbon.
Volume: 16.9 ounces
Tech specs: Two-stage ultrafiltration membrane with a hollow fiber filter and granular activated carbon
Weight/size: 2.9 ounces
LifeStraw Flex with Soft Bottle
Flexible bottles are ideal for space saving issues and to easily transport water from one vessel to another. With the LifeStraw Flex, you get a soft bottle and a built-in filter in the straw to filter heavy metals, bacteria, parasites, microplastics and pesticides for 500 gallons of water. The carbon filter helped with better tasting and smelling water, unlike the Katadyn BeFree, which doesn’t have any activated carbon to eliminate odors. Although you are sucking up water through the straw with the built-in filter, it is easier to drink from because it’s simple to squeeze. A warning to users: the mouthpiece is extremely small. Another downside is that once the water level is below the straw’s length, it is really tricky to get any water out, which means of the 22 ounces, you aren’t able to drink that much at all. Since the straw’s almost half as long as the flexible bottle, you aren’t able to squeeze or roll the entire system up like the Katadyn BeFree. On the plus side, you can also use the filter with other vessels, as it can screw onto a regular-sized plastic water bottle, can be used simply as a straw or can work in-line with your hydration bladder.
Volume: 22 ounces
Tech specs: Hollow fiber micro-filtration membrane (0.2 microns) paired with a carbon fiber filter
Weight/size: 3.15 ounces
Note: Purchasing products through our links may earn us a portion of the sale, which supports our editorial team’s mission. Learn more here.
