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The Best Gravity Water Filters for Hunkering Down and Bugging Out


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Last Updated: November 17, 2020

While I’m a big fan of squeeze and pump type water filters, manually filtering water for a large group of people is a tedious, time-consuming task. It’s much better to let gravity do the work for you. But, because gravity filters are prone to clogging and bursting, it’s imperative that you get a really good gravity water filter.

Below are the best gravity water filters reviewed and recommended based on factors like what they treat, filter lifespan, flow rate, and versatility.

Best Overall

LifeStraw Flex with Gravity Bag

This affordable gravity filter can also be used as a straw or squeeze filter. It reliably removes bacteria and protozoa for 2,000 liters. The carbon capsule filter only removes chemicals for up to 100 liters but replacement cartridges are cheap.

Best for Wilderness Use

MSR Trail Base

The MSR Trail Base works as a gravity filter or a pump filter to remove bacteria and protozoa. The smart design means it doesn’t clog as quickly as others and it is easy to use in the field.

Best for Home Use

Travel Berkey

The Berkey tabletop gravity filter removes virtually all types of contaminants from water, making it great for purifying water while hunkering down at home.

Comparison Table

ProductTreatsLifespanOther Uses


Lifestraw Flex
Bacteria, protozoa,
chemicals, bad tastes
2,000 liters (hollow-fiber)Straw, squeeze

LifeStraw Family
Bacteria, protozoa,
viruses
18,000 litersNo

MSR Trail Base
Bacteria, protozoa1,500 litersPump filter

Platypus GravityWorks
Bacteria, protozoa1,500 litersNo

Katadyn Gravity Camp
Bacteria, protozoa1,500 litersNo

Sawyer One-Gallon Gravity
Bacteria, protozoa400,000 litersStraw, squeeze

Travel Berkey Gravity
Bacteria, protozoa,
viruses, chemicals, bad tastes
24,000 litersNo

Best Gravity Water Filters Reviewed

LifeStraw Flex with Gravity Bag

Why Choose? You need a versatile water filtration system at a low cost

Specs:

  • Can be used as: Straw, squeeze, gravity filter
  • Size: 4 liters
  • Output: 30L/hour
  • Bacteria/protozoa: Yes
  • Viruses: No
  • Chemicals/bad tastes: Yes
  • Filter medium: 0.2 micron hollow fiber and activated carbon
  • Lifespan: 2,000 liters (hollow-fiber), 100 liters (activated carbon)

Review:

While I’m not a fan of the original LifeStraw (see why we prefer the Sawyer Mini), the LifeStraw Flex with gravity bag is a cool setup. You simply attach the Flex filter to the included 1 gallon gravity bag, hang it high up, and aim the water which comes out into a (preferably) wide-mouthed bottle.

There is a two-stage filtration system. The first stage is a hollow fiber filter which removes bacteria and protozoa. The second-stage is an activated carbon filter which removes chemicals and bad tastes.

The downside is that the LifeStraw Flex gravity system is SLOW. For clear water, you might get the advertised 30 liters per hour. In practice, you might only get 1 liter per hour if the water is even slightly murky.

Also expect the filter to get clogged frequently and spent a lot of time backflushing it. Further, there are many reports of the Sawyer Flex Gravity leaking where the hose connects to the filter.

On the positive side, the Flex filter can be unscrewed from the gravity bag and used as a straw or screwed on a plastic bottle to use as a squeeze filter.

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Pros

  • Use multiple ways
  • Affordable
  • Two-stage filtration
  • Wide-mouth bag is easy to fill and clean
  • Hydration pack compatible

Cons

  • Incredibly slow
  • Prone to clogging
  • Hose often leaks at filter connection site

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LifeStraw Family Portable 1.0 Gravity Powered Water Purifier


Why Choose? An affordable solution which also removes viruses from water.

Specs:

  • Can be used as: Gravity filter
  • Size: 2 liters
  • Output: 9-12L/hour
  • Bacteria/protozoa: Yes
  • Viruses: Yes
  • Chemicals/bad tastes: No
  • Filter medium: 0.02 micron hollow fiber
  • Lifespan: 18,000 liters

Review

While the LifeStraw Family might look like their other water filters, it’s actually a very unique design. The filtration system consists of a plastic jug with a pre-filter inside it. You pour water into the jug, it passes the pre-filter and then goes down a tube to the 0.02 micron hollow-fiber filter. Larger particles gather at the bottom of the filter and purified water comes out the blue tap at the top. The red tap can be opened to release contaminants.

Note that the LifeStraw Family is 0.02 and not 0.2 microns (like most water filters). At 0.02 microns, the LifeStraw Family is small enough to filter out most viruses as well as bacteria and protozoa. There is no activated carbon filter so the system won’t remove chemicals or bad tastes from water.

For a cheap gravity water filter, the LifeStraw Family does its job well enough. It doesn’t get clogged too easily because of the red tap to release contaminants. The red bulb cleans the membrane cartridge.

The downside is that the LifeStraw Family is not very portable. It weighs in at 1.6lbs and is very bulky to carry. The plastic will crack if you drop it so it’s not great for impromptu camps. However, it would work well for hunkering down at home.

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Pros

  • Removes viruses
  • Doesn’t clog too often
  • Built-in filter cleaner

Cons

  • Bulky
  • Do not drop!

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MSR Trail Base Gravity Water System

Why Choose? A well-designed system for wilderness backpacking or bugging out

Specs:

  • Can be used as: Gravity and pump filter
  • Size: 2 liters and 4 liters
  • Output: 1L/minute
  • Bacteria/protozoa: Yes
  • Viruses: No
  • Chemicals/bad tastes: No
  • Filter medium: 0.2 micron hollow fiber
  • Lifespan: 1,500 liters

Review

MSR makes serious products for outdoor use, some of which were designed for the US Military. Their Guardian filter is one of our top picks for survival water filters. The Trail Base system is one of the smartest designs for a gravity filter that I’ve seen. It is also versatile since the gravity filter component can be removed and used as a pump filter for when you need water quickly.

The gravity filtration system comes with a dirty water reservoir (4L), a hose, the filter, and a clean water reservoir (also 4L). You don’t have to use the clean water reservoir; the filter can be aimed into any water bottle or directly into your mouth.

One thing I love about the MSR Trail Base gravity filter is that the outlet hose is set slightly up on the side of the bag to create a sediment trap. With other filters, the outlet is at the bottom of the bag which means it quickly gets clogged by falling sediment when filtering murky water (think pond scum). With this system, sediment won’t affect the outlet hose.

The reservoir bags on the MSR Trail base are actually very tough. In theory, you could even attach them to the top of your pack and filter water as you trek. The wide-mouthed bags are easy to fill and can be flipped inside out to dry. Another cool feature is that you can drink directly from the clean water reservoir.

Note that the filter on the Trail Base is not the same as the MSR TrailShot. Even though it looks similar, it isn’t compatible with the system.

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Pros

  • Use as gravity or pump filter
  • Not as prone to clogging
  • Sediment trap in reservoir
  • Reservoir bags are very tough
  • Easy to pack and use in the field

Cons

  • Doesn’t filter viruses or chemicals
  • Pricier option
  • Short lifespan

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Platypus GravityWorks

Why Choose? You need a sturdy gravity filter for backcountry use

Specs:

  • Can be used as: Gravity filter
  • Size: 2L, 4L or 6L
  • Output: 1.75L/minute
  • Bacteria/protozoa: Yes
  • Viruses: No
  • Chemicals/bad tastes: No
  • Filter medium: 0.2 micron hollow fiber
  • Lifespan: 1,500 liters

Review

The Platypus GravityWorks was one of the first gravity water filters on the market and, because of that, it is still one of the most popular. I personally don’t like it nearly as much as the MSR Trail Base system and think that the MSR is designed better.

The Platypus gravity filter would be much better if it also had a sediment trap and the reservoirs were wide-mouth for easily filling and cleaning. However, the Platypus gravity filter is somewhat cheaper and holds up well enough to be used for emergency prepping.

Like most water filters, the GravityWorks is a 0.2 micron hollow fiber filter. It has a lifespan of 1,500 liters (though may clog well before this) and it’s easy to buy replacement filters. The two reservoir bags are pretty sturdy and can handle the rigors of camping or backpacking. If they break, you can buy replacements easily.

One nice feature is that the dirty water reservoir has a valve which automatically closes when you disconnect the hose. This will keep you from disconnecting and accidentally spilling water all over yourself (yes, it has happened to me).

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Pros

  • Comes in various sizes
  • Fairly durable
  • Replacement parts readily available
  • Quick-disconnect valve on reservoir
  • Has hose clamp for stopping water flow

Cons

  • Clogs fairly quickly
  • Dirty water reservoir is hard to clean
  • Not wide mouth; hard to fill

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Katadyn Gravity Camp Water Filter


Why Choose? Affordable gravity filter for large groups

Specs:

  • Can be used as: Gravity filter
  • Size: 6 liters
  • Output: 2L/minute
  • Bacteria/protozoa: Yes
  • Viruses: No
  • Chemicals/bad tastes: No
  • Filter medium: 0.2 micron hollow fiber
  • Lifespan: 1,500 liters

Review

Katadyn makes a few different gravity water filters. The BeFree Gravity Filter is their best-known product but I didn’t include it in this list; the reservoirs on the BeFree are simply too flimsy and prone to bursting or leaking. However, the Katadyn Gravity Camp filter is a good option for filtering large amounts of water in wilderness areas.

The first noteworthy feature of the Gravity Camp filter is that it has a large, sturdy reservoir with a wide mouth. It’s easy to fill and can be put inside out to clean or dry. The 0.2 micron filter actually sits within the reservoir so the water flow is faster than if the filter were inside the hose. Because the filter sticks up within the reservoir, the bottom of the bag acts as a sediment trap.

There are actually two parts to the filter: a “protector” which acts like a pre-filter and the cartridge. You can clean the filter in the field but it is a bit annoying to do. Instead of back-flushing, you have to remove the entire cartridge, wash the protector with a sponge, and swish the cartridge with clean water. Even with these steps, the Katadyn Camp Gravity filter still clogs easily. Don’t expect to get the full 1,500 liters advertised, especially if the water is murky.

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Pros

  • Good flow rate
  • Sturdy reservoir
  • Hydration pack compatible
  • Converts to shower with optional adapter
  • Affordable option
  • Quick-disconnect valve on reservoir

Cons

  • Prone to clogging
  • Doesn’t remove viruses or chemicals
  • Cleaning filter in field is annoying

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Sawyer 1 Gallon Gravity


Why Choose? You want a cheap gravity filter that you can hack and improve upon

Specs:

  • Can be used as: Straw, squeeze or gravity filter
  • Size: 4 liters
  • Output: 0.8L/minute
  • Bacteria/protozoa: Yes
  • Viruses: No
  • Chemicals/bad tastes: No
  • Filter medium: 0.1 micron hollow fiber
  • Lifespan: 400,000 liters

Review

I have a Sawyer Mini water filter and absolutely love it because it’s cheap, very simple to use, and lasts a lifetime (I did have to replace the O-ring after 5 years of use). The Sawyer gravity filter system utilizes the Sawyer Mini but with an important change: it is dual-threaded (the original Sawyer Mini has threads on just one side).

The dual threads mean you can connect one end to a hose and reservoir (both included in the Gravity Filter Kit). Attach the other end of the Mini filter to a clean-water reservoir, a water bottle, or just angle it into your pot: gravity will have clean water coming out.

Unfortunately, there are some serious design flaws in the Sawyer Gravity filter system. The first is that the reservoir doesn’t have a wide mouth. It’s annoying to fill and even more annoying to clean. It’s also a very poor quality. Like the other Sawyer reservoir bags, expect it to leak or burst quickly. I also wish the reservoir were transparent so you could see how much water is left.

The flow on the original Sawyer Mini is painfully slow, and that’s when you are putting pressure on the filter. With just gravity applying the pressure, the filter is even slower. You probably won’t ever get the 0.8 liters per minute advertised, even with clear water.

If you need water immediately, you can unscrew the Mini filter and use it as a straw (though you’ll have to stick your face really close to the water) or as a squeeze filter when attached to a bottle/pouch.

While I definitely don’t think that this is the best gravity filter, I do love how easily it can be hacked. You can use any pouch with a standard 28mm thread as the reservoir. You can even insert your own DIY activated charcoal filter into the hose. So, if you are the DIY type and willing to put forth a bit of effort, the Sawyer Gravity filter is a versatile solution.

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Pros

  • Versatile: use as a straw or squeeze filter
  • Filter lasts a lifetime
  • Back-flush to clean clogs
  • Easy to hack and improve on design
  • Very affordable

Cons

  • Reservoir bags are terribly designed
  • Painfully slow flow rate

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Travel Berkey Gravity Fed Water Filter System


Why Choose? You are willing to spend more for a filter which removes almost all types of contaminants

Specs:

  • Can be used as: Gravity filter
  • Size: 1.5 gallons
  • Output: 0.18 liters per minute
  • Bacteria/protozoa: Yes
  • Viruses: Yes
  • Chemicals/bad tastes: Yes
  • Filter medium: 6 different media
  • Lifespan: 24,000 liters

Review

As far as gravity water filters for home use go, Berkey is one of the most popular and trusted brands. Their gravity filters are simple to use: just pour water in the top tank, wait for it to filter into the bottom tank, and use the spigot to get clean water. The Berkey filters even look nice too since they are made from stainless steel.

The Travel Berkey comes with two black filter elements. It isn’t exactly portable but it would work great for hunkering down. They also have a smaller filter, the “Berkey Go”, but I personally find it too bulky and ineffective to make it worth getting. The Travel Berkey works better and is still small enough to fit in your car.

Berkey doesn’t give much information about what these filters are made from other than it contains 6 different filter media. Based on what they claim on their website, it’s safe to assume that the filters are probably a combination of a small micron hollow-filter (likely 0.02 microns to remove bacteria, viruses, and larger contaminants) and some kind of activated carbon brand (to absorb chemicals and bad tastes/smells).

If I had to hunker down at home through an emergency, I’d still prefer bottled water for drinking. But, if I ran through my water stockpile, I’d trust the Berkey to make water sources safe to drink. The caveat is that, if the water were contaminated with chemicals, the black filter would need to be replaced long before the advertised 6,000 gallon lifespan.

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Pros

  • Removes or reduces all types of contaminants
  • Long filter life
  • Easy to use
  • Optional filters for removing arsenic and fluoride

Cons

  • Expensive option
  • Not very portable

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