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What is a Gravity Water Filter?

A gravity water filter system uses gravity to force water through a filter so you don’t have to squeeze it manually or use a pump to push it through. The advantage of a gravity water filter system is that you can process large quantities of water without much effort. This is beneficial if you’re hiking with a partner, with your family, or in a large group. If you had to wait for everyone to process their own water, you’d be there all day.

You can buy gravity water filter systems off the shelf or assemble your own from components. Most off-the-shelf gravity filters include a multi-liter reservoir (with a hanging strap) to hold raw unfiltered water that you’ve collected, a water filter or purifier to process your water, and all the required hosing to connect the components. Some like the Platypus Gravity Works Gravity Filter System also include clearly labeled “Dirty” and “Clean” reservoirs so you can store the filtered water and not confuse it with raw water that must still be treated.

Units that only have one reservoir for use as a “Dirty” bag often come with a valve that lets you decant clean bottles of water as needed, rather than collecting it all at once in a clean reservoir. This can be handy in base camp situations so people can get a refill whenever they need one or if you use water bottles instead of a reservoir to carry your clean water.

Homegrown gravity filter setups use a dirty bag, clean bag, filter setup but may also require extra hoses and adapters to make the components compatible with one another. That’s the advantage of buying an off-the-shelf gravity water filter system from one manufacturer: you know it’ll all work together.

Most commercial gravity filter systems come with water filters that remove protozoa and bacteria like Giardia, salmonella, and cryptosporidia. But you can also find gravity water purifiers that also remove viruses like the high volume 12L Lifestraw Mission Gravity Water Purifier or the 10L MSR Guardian Gravity Purifier. These are good for international travel or places where viruses in the water supply are a concern.

You can read Philip Werner's complete explanation on what a gravity water filter is here


May 8, 2022

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Section Hiker

Media Mentions from Section Hiker

Philip Werner is a full-time outdoor author and backpacker who resides in New England. His website is ranked as the #1 Hiking and Backpacking Blog on the internet by in 2018, 2019, 2020, and 2021.

The name of this site, Section Hiker, refers to the Long Trail which I section hiked in 2008 and the Applachian Trail that I’m still working through. To date, I’ve completed 1400 miles of the AT and hope to complete all of the sections between Georgia and Maine someday. I’ve also hiked thru-hiked the TGO Challenge (Coast-to-Coast across Scotland) twice and I’m currently section hiking the Cape Wrath Trail, also in Scotland.


While DEET products may be more familiar by name and their chemical smell, sprays with 20 percent picaridin, like Sawyer Products, offer comparable protection without the harsh odor and oily feeling on your skin.

Kevin Brouillard
Travel & Leisure


The Sawyer Squeeze was (by far) the most common Pacific Crest Trail water filter this year – for the fifth year in a row. It’s a $39, 3 oz / 85 g hollow fiber filter that rids your drinking water of protozoa and bacteria (and floaties). It can be used with Sawyer bags (included with the filter) or with compatible water bottles (Smartwater is the bottle of choice for many hikers).

Halfway Anywhere
Media Mentions from Halfway Anywhere


SAWYER MINI WATER FILTER, $22 This has been my water filter of choice for years now. The bags can be iffy — I have had a few break – so carry a couple. However, the filter itself is reliable, light and inexpensive. -Logan

Bikepacking Team