Hydrapak Flux+ 1.5L Review

The Hydrapak Flux+ 1.5L is a collapsible water filter with a durable, sturdy, soft bottle construction. It weighs only 5 ounces and packs down flat-ish for storage when making your way through the backcountry. And its competitive filtration time will keep a single person well-hydrated while moving on the trail. The user-friendly bottle is also easy to maintain in the field, making it perfect for those who want something that can take some scrapes and tumbles and keep going.

Water Quality

The Flux+ .5L features a hollow fiber filter with 0.2-micron pore size designed to filter harmful bacteria, protozoa, and microplastics along with sediment found in murky water sources. Third-party testing performed by SGS Labs revealed that the Flux+ lives up to the manufacturer's claims, eliminating 99.9% of bacteria and protozoa. It only removed 29.5% of viruses; however, Hydrapak does not claim this to be in the wheelhouse of the Flux. When traveling in remote locations or popular trails throughout North America, getting rid of the bacteria and protozoa in your water is your main concern anyway.

Throughout our testing period in Cochamó, Chile, our test team was impressed by the overall water quality, which remained consistent no matter the source. The Flux+ handled turbid waters after heavy rains better than other filters under testing, resulting in only a small quantity of sand particles sinking to the bottom of the bottle. In just over 30 seconds, our testers were hydrating with high-quality water that looked clear, didn't smell weird, and tasted great.

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Ease of Use

The Flux+ 1.5L is shipped to your door already set up and ready to go. Simply fill the soft bottle with water, whether at home or from a fresh water source once off on your adventure. There is no max fill line on this bottle, and we noticed that when it is filled to capacity, some water overflows out of the top of the twist cap, which is annoying, but easy to avoid by filling it a little bit less. The twist-to-drink nozzle is easy to manage with one hand, and the design features a dust cap that protects your mouthpiece from dirt encountered along the trail.

Unless you're used to the hand-free convenience of a gravity-fed filtration system, you won't find any filter much easier to use than the Flux+ 1.5L. Just fill your bottle from a stream or other water source and then roll or squeeze it down to press the water through the filter. Just note that the structured oval shape at the top of the bottle can make it difficult to collect water from very shallow sources.

The Flux+ 1.5L is versatile enough to use directly in an open water source. If you are filtering into another bottle, the high-flow nozzle is easily opened or closed, allowing you to secure the full bottle in your pack between sources. Our only complaint here is that we wish the kit came with a plain screw cap for transporting water. As is, the filter is fixed to the lid and must remain inside the bottle at all times.

Durability & Maintenance

The soft bottle on the Flux+ 1.5L is made of abrasion-resistant TPU using welded seams to ensure strength despite its flexibility. The dual-layer laminate also provides more structure and thickness to the bottle than any other soft bottle filter design we've tested. We put the durability of the Flux+ 1.5L to the test during an extended trip to Cochamó, Chile. We found that no matter if we were scraping our way up sharp chimneys or shoving our bodies into off-widths, the soft bottle remained intact, only showing cosmetic scuffs and abrasions at the end of each day.

Maintenance is an often overlooked consideration when making an initial purchase, but it can ensure you get full value from whichever filter you buy. We found the Flux+ 1.5L particularly easy to handle in the field. Like many other squeeze bottles, it generally needs care after processing turbid water from heavy rains or murky streams with limited flow. Simply remove the filter from the bottle before shaking and swishing it around in a clear water source.

Hydrapak warns against allowing your filter to freeze, as this could significantly damage or even ruin the hollow fiber membrane. It's also nice to know that Hydrapak offers a lifetime warranty for their products should you encounter an issue with the design.

Treatment Time

Hydrapak advertises a flow rate of one liter per minute; our testers consistently measured a treatment time between 28 and 38 seconds. When recording the treatment time, we noticed that the filter worked faster when the 1.5-liter bottle was filled to capacity. The additional pressure helps to move the water through the filter more quickly when full. We also noted that squeezing typically offered a faster flow rate than the rolling technique.

Aside from the full vs. empty variation, we never saw a change in the flow rate, even after using it daily throughout our month-long expedition to Cochamó Valley. Luckily for our testers, the only turbid water they encountered during the trip was on the final hike out to the trailhead, where, after a couple of days of heavy rain, the rivers were filled with more silt and sediment than on previous days. This slowed their measured treatment time by 10 seconds. However, despite that final day of slower results, our team was still pleasantly surprised by the flow rate; overall, it was far faster than advertised.

Weight & Packability

While the Flux+ 1.5L isn't the lightest collapsible bottle we tested, its ease of filtration, durability, and dependability make it worth the extra couple of ounces, especially if you know you're hard on your gear. Weighing in at 5 ounces and measuring 10 by 4.5 inches when filled with water, the Flux+ also features a flexible design that can be rolled down and packed into a small pocket when not in use.

Although we wish the design included a separate cap so the bottle could be utilized without the hollow fiber filter installed, this absence didn't stop our testers from carrying the filter on many multi-pitch rock climbs in the remote Cochamó Valley. The flexible handle is super durable and makes this bottle easy to attach to your harness or interior backpack strap for easy access. The handle can also be folded over the rolled bottle to reduce its packed size.

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Should You Buy the Hydrapak Flux+ 1.5L?

The Hydrapak Flux+ 1.5L is a collapsible water filter that delivers tough-to-beat performance. Although slightly more expensive than other collapsible designs, the durable and sturdy construction will outlast the competition. It's worth noting, though, that the filter has a shorter lifespan of 396 gal, driving up the cost over time. It scored near the top of our charts, so you won't be disappointed by this filter, but in the end there are others we would prefer to take with us into the backcountry.

What Other Backpacking Water Filters Should You Consider?

Another stand-out collapsible filter is the LifeStraw Peak Squeeze, which includes its own durable, collapsible bottle. While it isn't as structured or easy to use as the Flux+ 1.5L, it boasts an even lighter weight and a filter that lasts up to 500 gallons. The Katadyn BeFree is another popular collapsible bottle that's easy to use and extremely lightweight and packable. However, it doesn't offer nearly the same durability as the Flux+ or the Peak Squeeze, but gram counters out there might be ok with the trade. If you like the idea of a lightweight, collapsible design but need to filter enough water to satisfy a group of 3-4 people, check out the LifeStraw Peak Gravity 3L and let gravity do the work.