The Best Water Filters and Purifiers of 2024: Staff Picks

The best feeling after logging miles on foot: quenching your thirst from an icy stream. But drinking from Mother Nature's tap isn't like flicking on a faucet at home. You have to treat the water first, using either a water filter or a purifier to remove harmful contaminants.A water filter guarantees access to safe drinking water by removing harmful impurities from natural sources like rivers, lakes and streams. Whether you're treating water in the backcountry or on an international trip, a water filter or purifier is an invaluable tool. Carrying one also reduces reliance on single-use plastic bottles by allowing you to fill up a reusable vessel wherever your adventures take you.You might hear the terms "filter" and "purifier" used interchangeably, but there are subtle differences between the two. A water filter strains out bacteria, protozoan cysts and other impurities. A water purifier removes these contaminants plus viruses, which are often too small for most water filters to catch. (Related reading: How to Choose a Water Filter or Purifier)Choosing a water filter or purifier is like selecting any piece of adventure gear: There are plenty of products available, but you'll want to pick the one specific to your needs and preferences. We consulted seasoned REI Co-op staffers and combed through customer reviews to narrow down favorite filters and purifiers for everything from camping to international travel. These are their seven favorites.Staff PicksFind quick recommendations below or scroll down for in-depth reviews.Best Overall Water Purifier: MSR Guardian PurifierBest Water Filter for Backpacking: Katadyn BeFree 1.0 L Water Filter Bottle - 33.8 fl. oz.Best Water Filter for Camping: Platypus GravityWorks Water Filter System - 4 LiterBest Portable Water Filter for Travel: Grayl GeoPress Water Filter and Purifier Bottle - 24 fl. oz.Best Water Filter for Large Groups: MSR AutoFlow XL Gravity Filter - 10 LiterMost Affordable Water Filter: Sawyer Mini Water FilterBest Water Purifier for Emergencies: Potable Aqua Iodine TabletsBuying AdviceWater Filters vs PurifiersBefore you buy a water filtration device, you need to determine whether you need a filter or a purifier. The main difference between a water filter and a water purifier is the size of the microorganism each combats. (Related reading: How to Choose a Water Filter or Purifier)Water filters work by physically straining out bacteria (such as E. coli, salmonella, campylobacter and shigella), protozoan cysts (such as cryptosporidium and giardia lamblia), and other impurities and debris that could be harmful or affect the taste, odor or appearance of the water. "A filter will take care of most of the stuff that you're going to face in the U.S. and North America if you're camping, backpacking, or hiking," says Christa Lindsey, a program coordinator at REI.Water purifiers "take care of all of those same things plus viruses," Lindsey says. They eliminate microbes that are too tiny for most water filters to catch (such as hepatitis A, rotavirus and norovirus). "If you're traveling internationally or to areas of the world where you're concerned about fecal contamination of the water from a human source, that's where you'd really want to focus on having a purifier, not a filter," says Lindsey. They're also ideal for natural disaster response and emergency preparedness. (Related reading: How to Maintain Your Emergency Kit)Types of Water Filters and PurifiersWater filters work using different mechanisms depending on their type.Mechanical filtration, sometimes called physical filtration, refers to water passing through an internal element or cartridge with microscopic pores that catch debris, protozoa and bacteria. This method physically strains out particles and larger impurities by forcing water through a physical barrier, often made of paper, ceramic or specialized hollow-fiber membranes. Over time, strained matter clogs up a filter's pores, requiring it to be cleaned and eventually replaced.Some common mechanical filtration types are:Pump filters work by physically forcing water through a filter medium, typically using a hand-operated pump mechanism. Pump filters allow you to filter only the water you need, and they're good for processing large volumes of water. But pumping can be a chore, especially at the end of the cartridge's lifespan.Gravity filters utilize the force of gravity to pull water through a filter. Most models come with a pair of reservoirs and an inline filter. Dirty water stored in the higher-hanging bag flows through the filter into the clean reservoir. These are convenient for filtering larger quantities of water without much effort, but you need a place to hang the setup and a water source deep enough to fill the bag.Straw or squeeze filters work by forcing water through a filter, either by squeezing water through a filtration system or by directly drinking through a strawlike device that contains a filtering mechanism. They are ideal for individual use, and they're usually lighter, more compact, and cost less than pump or gravity filters. However, they require more cleaning in the field. With some straws, you can only drink from the source and can't store any water.Bottle filters and purifiers have built-in mechanisms that allow you to fill the vessel with dirty water and drink clean water through a spout, just as you would with a regular water bottle. Some use the suction provided when you sip from a bite valve to filter water, while others work like a coffee press. They offer quick access to drinkable water and are light and easy to pack, but water quality is limited by bottle size and they require field-cleaning.Chemical purification like chlorine dioxide tablets or iodine can effectively neutralize microorganisms in water, killing viruses that are too small for most filter elements. They are lightweight and portable but require waiting time for the chemicals to take effect. Iodine has a very distinct aftertaste that many people don't like, especially if you're drinking in large quantities over a long period. You can add some taste neutralizers, but there's still an aftertaste, which is why some people prefer chlorine dioxide (though this method takes longer to clean the water and has a shorter shelf life). Chemical tabs are great as a backup to other filtration systems or stashed in an emergency kit.Activated carbon filtration uses carbon to soak up industrial chemicals, heavy metals, pesticides, and other contaminants. It can also neutralize bad smells and taste.UV purifiers are pen-like devices that use ultraviolet light to disinfect water, destroying bacteria, viruses and other microorganisms without physically removing them. They are typically compact and easy to use but rely on batteries or a power source.Ease of UseEase of use is an important factor to consider when choosing a water filter. "Some are really simple," Lindsey says. For example, "If you've ever used a sports cap type water bottle, you'll know exactly how to use a water-bottle-style filter or purifier, and it'll be easy to use, " On the other hand, "some require more technical skills and prior practice. You may have to learn how to prime it or how to take it apart in order to backflush it while you're out in the field," Lindsey says.Ultimately, you want a filter that you feel comfortable and confident using—and some filters may require more practice and education than others before you head into the backcountry with them.Capacity and OutputCapacity refers to how much fluid your filter can hold (if any), and output denotes how quickly it can clean the water. The Platypus GravityWorks Water Filter, for instance, holds a lot more and cleans quicker than, say, the Sawyer Mini Water Filter. But the smaller filter may make more sense if you're embarking on a one-night solo camping trip.When choosing a filter, consider your group size, trip duration and activity. "Think about how many people you're filtering water for and how frequently you think you'll need to filter water," says Lindsey. "Are you going on a longer trail run day and just need to filter water for yourself a few times along that run? Or are you backpacking with a group of scouts and looking to filter water at the end of the day for a large group?"(Related reading: Hydration Basics)Portability and WeightHow you plan to use your water filter will significantly determine its size and weight. Considering your intended usage is key; for a small-group backpacking or hiking trip, prioritize a compact filter that fits snugly in your pack and is field-maintainable. Larger groups may want to focus on flow rate and capacity over weight savings.Typically, a larger, heavier filter will be able to move more water through it faster because its filter element can hold and move more volume compared to a smaller one, says Lindsey. A smaller filtration device will often be lighter and more compact—but this comes at the expense of output. "Because it's smaller, there's just less surface area for the water to move through that filter," Lindsey says.Durability and LongevityConsider the durability of the filter as well as its components. Some questions to ask yourself: How long can this filter be used before parts need replacement? Are replacement parts readily available? How much do these parts cost? Is the filter or purifier durable enough to reliably filter water in challenging conditions?Knowing the lifespan of the parts and the availability of replacements ensures that you're equipped for extended trips and can swiftly address any maintenance needs. "If you're a person who doesn't like to do a lot of maintenance, maybe the [filter] that requires backflushing more frequently or [necessitates] a more involved process to maintain isn't right for you in the long run," Lindsey says.Maintenance and CleaningSpeaking of maintenance: Each filter has its own cleaning and care requirements, and some are more user-friendly. Some filters need frequent backflushing, while others need filter replacements after a certain number of uses. When it comes to maintaining your water filter, one REI customer-reviewer has great advice: "The key to longevity is proper cleaning and maintenance. Always store the [filtration] system cleaned and dried. Also, be sure to run some water through the system and backflush the filter before heading out so that you're not stuck at your first watering site trying to make sure your filter is still working!"PrefilteringPrefiltering water involves an initial stage where larger particles and sediment are removed to prevent clogging and enhance the efficiency of the main filtration process. "Prefiltering will help extend the filter's life before it has to be backflushed or replaced entirely," says Lindsey. People can use methods and techniques to do this manually, but some devices have prefilters built in. "It's important to either figure out a way to prefilter your water or be ready to back flush or replace that filter more frequently," she says.Always Test at Home FirstWe can't stress this point enough: Testing and practicing with your water filter before heading outdoors is crucial to ensure its proper functionality and preparedness. It familiarizes you with its operation, allowing you to troubleshoot any issues and streamline usage in the field.MethodologyWe chatted with REI Co-op staffers and read dozens of customer reviews to pick the best water filters in each category. These selections represent their firsthand experiences and favorite picks.Related articles:Hydration BasicsHow to Choose the Right Water Filter for BackpackingHow to Treat Water in the Backcountry