Choosing a Portable Water Purifier

When deciding which portable water purifier to purchase, consider ease of setup and use. The best systems work with little thought or instructions and are easy to use on the go.


Look for purifiers with a pore size that eliminates bacteria and protozoa (but not viruses). Also, look for devices that adapt to your existing water bottle or come with their own vessel.

Ease of Setup

The most convenient and lightweight options for water filtration and purification are on-the-go systems that require little thought and few instructions. The best example is the basic Lifestraw Go. This is one of the most compact, portable, and simple backpacking water filters available that routes untreated water through an actual filtering sieve to remove bacteria, protozoa (cysts), and viruses. Other on-the-go systems include the Sawyer Mini and the Steripen Adventurer, which both attach to bottles and use a small reservoir for pre-filtration and then dispense clean water directly into your bottle.

Pump filters like the MSR Guardian and Katadyn Hiker are another popular option for backpacking. While these provide high reliability and longevity for the upfront investment, they do require some maintenance in the form of regular backflushing and squeezing to keep the flow rate high and pump fatigue at a minimum. The MSR Guardian is particularly effective for international travel because it kills viruses in addition to bacteria and protozoa, and its self-flushing system eliminates the need for a separate pump for turbid water.

Chemical and ultraviolet treatment systems are another way to sanitize backpacking water. These are especially useful for groups and time-conscious outings because they don’t have to be activated or used in tandem with a water bottle, so hikers can continue on their trek while the treatment system works its magic. However, chemical and UV treatment can add an undesirable taste to the water and take from 30 minutes to four hours to kill Cryptosporidium oocysts.

Ease of Use

Regardless of whether you choose a filter or purifier, the best models will be easy to use. We always prioritize treatment options that don’t require a lot of pumping or squeezing, so that you can treat water quickly and easily on multiple outings a day in the backcountry.

Filters and purifiers are the simplest to operate, with designs that fit directly onto your drinking vessel of choice. Some, like the Sawyer Mini and LifeStraw Go, are designed to attach to hydration bladder hoses, while others, such as the Platypus GravityWorks and the Katadyn QuickDraw, work with any wide-mouth Nalgene bottle.

Compared to filters, chemical and UV purifiers add an extra step in your backcountry process. Chemical purifiers (iodine or chlorine dioxide tablets) and UV purifiers (the SteriPen Ultra, for example) both treat water without filtering it, so they’re ideal if you have access to clear water sources like glacial streams.

A chemical water purifier adds an unwanted taste to your water, while a UV light purifier requires a battery and electronics, which isn’t great for backcountry camping trips. Thankfully, there are plenty of middle-ground options available. Filters like the MSR Guardian remove bacteria and protozoans and can be used with a hydration bladder hose, while UV purifiers like the Steripen Adventurer are small enough to fit into a hydration bottle and kill pathogens with just a few flicks of the wrist.

Ease of Maintenance

A water purifier can be one of the most affordable pieces of backpacking gear you ever buy. For just a few trips, you can break even with most models, and then it’s just a matter of saving money on bottled water forever. Plus, you’ll be helping to cut down on the number of single-use plastic bottles that are purchased around the world – a staggering 481.6 billion per year, according to Reuters.

By definition, a water filter routes water through an actual sieve, which removes particles from the liquid (think dirt, algae, leaves, and small critters). Most filters don’t sterilize or kill bacteria or protozoans, though some do (see our review of the Lifestraw Go), but they can make muddy river or murky pond water much more palatable. UV filters sanitize by using ultraviolet light to kill bacteria, protozoa, and viruses. They don’t have the same filtering capabilities as a physical filter, but are an ideal option for treating contaminated water straight from its source (though they can add an unpleasant flavor to the drinking water).

Chemical and ultraviolet treatment methods don’t have a flow rate like a filter does, but they also don’t require pumping or squeezing as you do with pumps and gravity systems. They do, however, have a wait time – 15 to 30 minutes for a chemical purifier or four hours for the SteriPen – and a few of them, like the Aquamira Potable Aqua or the Grayl Geopress, have a backflush system that makes field maintenance easy.

Ease of Storage

A portable water purifier allows you to transform murky river and lake water into clean drinking water in a matter of minutes. You can also use one of these devices to treat a seep or shallow water source. These systems are typically lighter and smaller than pump and gravity filters, and most offer replaceable elements.

Some of these systems resemble a pen and are designed to be used with a wide-mouth Nalgene bottle (we recommend the Sawyer Mini). Simply insert the device into a water bottle and start “stirring” it. The light on the body of the device will turn off when the process is complete, meaning that a liter of water has been completely treated and safe to drink.

While this system provides an easy-to-use treatment method for backpacking and international travel, it doesn’t remove or kill viruses. If you’re traveling in areas where viruses are prevalent, you’ll want to invest in a treatment system that does.

Other systems require more work on the user’s part, such as a pump filter or a UV filter. Pump filters require manual pumping, which can be a challenge on the move, while UV filters sit in a water bottle to sanitize but need periodic charging. Alternatively, water treatment drops or tablets such as Potable Aqua Water Purification Tablets and Katadyn Water Treatment Drops provide an easy-to-use option that is lightweight and inexpensive, but they don’t offer as much protection against disease-causing pathogens.