LifeStraw Peak Gravity 3L Review

The LifeStraw Peak Gravity is our favorite gravity filtration system to use for small groups in the backcountry. It features an easy and user-friendly design with a fast flow rate, and it's available at a more affordable price than most group-sized filters. Whether you need to sip directly from a shallow stream, fill the entire reservoir to hydrate you and a friend, or store precious water between sources, the Peak Gravity offers performance along with easy maintenance so you get the most out of the life of the filter.

Water Quality

The Peak Gravity uses a 0.2-micron hollow-core membrane that LifeStraw claims to protect against bacteria (E. coli and Salmonella), parasites (like Giardia and Cryptosporidium), and sediment (microplastics, silt, sand, and cloudiness). During our testing period, we were impressed by the clear water quality, which did not have a lingering or pungent aftertaste, even when filtering in mineral-rich water after a few days of thunderstorms. But be cautious of your water source, if the water is too murky or turbid, it will easily clog this hollow fiber filter. It is not effective against viruses, heavy metals, or chemicals.

We were able to confirm LifeStraw's water quality claims by partnering with SGS Labs for third-party testing, where the Peak Gravity effectively removed >99.9% of all bacteria and beads representing protozoan cysts. And while LifeStraw doesn't claim this filter is effective at eliminating viruses, we were impressed to see that it was able to remove >73.6% of the viruses in the test samples. That said, if you know you'll be in an exposed area, we recommend purchasing a filter that's designed to remove viruses rather than trust your gut to a C minus rating.

Ease of Use

The Peak Gravity isn't the most intuitive system to set up. It helps to take a glance at the instructions first. Before filtering, remove the cap from the filter, then reattach it to the bag; this lets you attach the hose and begin filtering. We recommend setting up the filter before filling the soft bottle vessel with “dirty” water, as it's cumbersome to attach the hose. As soon as you fill the bag, the filter begins to work; that is, unless you use the plastic clip on the hose to stop the flow.

The filter comes with a nice, adjustable strap and a durable carabiner to facilitate an easy hanging setup for gravity-fed filtration. And if you don't have a spot to hang the filter, you can use it without the bladder to sip directly from the stream. You can also use it as a large squeeze bottle system, applying pressure to the bag to move water through the filtration system. While we love the versatility of this affordable gravity system, we noticed it was pretty difficult to fill the soft bottle vessel in shallow water sources. Unlike other gravity systems that we've tested with larger fill openings, the opening on the Peak Gravity is quite small, which is perhaps our only complaint regarding the filtration system.

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Durability and Maintenance

Premium materials that maintain weight savings make the Peak Gravity one of the best gravity systems that we've tested. The BPA-free TPU (Thermoplastic Polyurethane) soft bottle vessel is durable enough to hang against harsh materials like trees and rocks, while also sturdy enough to utilize as a storage container if you need to transport water between sources.

The Peak Gravity also comes with a backflush syringe that allows you to pass clean water through the filter to clear sand, silt, and other materials. This will make sure the filter stays clog-free and maintains a fast flow rate. LifeStraw advertises a 2,000-liter lifespan for the filter. Regular backflushing, along with appropriate storage, will help you maximize the life of the filter.

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Treatment Time

After testing this filtration system in multiple locations, we've noted treatment times that range anywhere from 30 to 90 seconds per liter, depending on the gravity setup. When you are able to find a large tree or boulder to hang the bladder and it has been recently maintained, we noted a flow rates of 30—35 seconds. The best part is that it's hands-free; just hang it up, place your clean water vessel underneath, and walk away. However, in places where there aren't great options to hang the bag in line, we noted treatment times of up to 90 seconds per liter.

If gravity isn't an option, the versatility of the filter can come in handy and reduce treatment time. If the flow rate is slow, you can always squeeze the soft vessel to help increase the flow rate for a faster time. If the water is particularly shallow, and you're having a hard time filling the bladder, you can use the filter as a straw to sip direct from the stream.

Weight and Packability

Weighing only 8.1 ounces, this is one of the lightest gravity filtration systems that we've tested. We like to fully remove the filter and hose before rolling it inside the durable, soft bladder vessel for easy transport that doesn't take up a lot of extra space in your backpack.

If you're stressed about packing all the essentials for your next adventure with a small group, you won't think twice about bringing this versatile water filtration system.

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Should You Buy the LifeStraw Peak Gravity 3L?

If you're interested in the convenience of a gravity-fed water filtration system for your next backcountry adventure, the Peak Gravity 3L far exceeds its modest price tag. The larger bladder size and ability to function as an in-line gravity filter make it a great base-camp option for small groups. This user-friendly design features a sleek and durable construction that's versatile enough to perform, no matter the water source and conditions, and it's available for a fraction of the cost of its competitors. The two caveats are that it doesn't come with a clean water vessel, so you'll have to BYO, and the small opening can be tricky to fill in shallow water sources. It's also larger than we like to bring for solo adventures or trail runs, so you'll want to look elsewhere if that's your jam.

What Other Backpacking Water Filters Should You Consider?

If you're willing to invest in another design that includes an even greater storage capacity, plus separate clean and dirty water vessels, we highly recommend the Platypus GravityWorks, it's our overall favorite for group use. The Waterdrop Filter Straw and Gravity Bag is another option you might be tempted to purchase if you're on a tight budget, but we have to be honest that we weren't impressed with the quality and durability of the design, nor the location of the filter, which makes it difficult to utilize the hands-free, gravity-fed feature.