Best Gravity Water Filters (2021 Value Guide)

Isolated image of a Platypus GravityWorks water filter with white background

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We can all agree that group camping is a fun way to spend time out the backcountry. What isn’t fun is contracting waterborne illnesses from contaminated water sources. Such as shallow streams and stagnant lakes. To protect yourself against bacteria and protozoa you need to filter before use. Plus, for group camping you need larger volumes of water than solo users do. Therefore, it’s ideal to buy the best gravity water filters you can afford.

Not sure if you need a water filter or purifier? Check out our comprehensive how-to guide.

What Do Water Filters Remove?

All the water filters in this review article will remove 99.9% of contaminants such as bacteria and 99.9% of protozoa. Both of which are harmful waterborne pathogens to humans. One kind of contaminant a water filter won’t remove is viruses like Rotavirus or Norwalk Virus’s. Viruses aren’t common to North America, to remove this type of pathogen you need to use a water purifier.

Neither will most of these water filters remove pollutants like mercury or lead and chemicals like herbicides. To remove chemicals and heavy metals, the system has to include activated carbon element.

To make your reading easier, there’s a table of content you can use to navigate to a specific review. Or read the entire buyers guide to get the full picture. Let’s get started and discover the top rated gravity water filters in 2021.

We updated this review article in January 2021 to ensure that the products meet today’s standards.  Read on to discover the best gravity water filters in 2021.

Comparison Chart

Best All-Around Gravity Filter For Large Groups

Purple label with gold anchor stating Editor's choice
Sale
Platypus GravityWorks
  • Capacity: 4 Liters
  • Flow Rate: 1.75 Liters Per Minute
  • Weight: 11.5 Ounces
  • Filter Pore Size: 0.2 Microns
  • Cartridge Media / Life: Hollow Fiber / 1500 Liters
  • Dimensions: 9.5 Inches (L) x 3.25 Inches (W)
  • Includes: 4-liter Dirty Water Reservoir, 4-Liter Clean Water Reservoir, Hollow-Fiber Microfilter, Hoses, Shutoff Clamp, & Storage Sack
What We Like
What We Do Not Like

Platypus GravityWorks Review:

The Platypus GravityWorks 4 Liter is the best group camping gravity water filter for 2021. This filter system wins because it’s reliable, quick to filter and versatile. It filters 4 liters or 1.05 gallons of water via a 0.2 microns hollow fiber filter. It removes 99% of contaminants or bacteria like E. coli, salmonella, cholera. Plus 99% of harmful pathogens called protozoa which includes Giardia, known as “beaver fever.” 

Expect it to clean 1500 liters of drinking water before you need to replace the cartridge. Weighing in at 11.5 ounces (42.52 g) it’s heavy but a good option for base camps. In total, you get a 4-liter dirty water bag, 4-liter clean bag and hollow-fiber filter. Plus the hoses, a shutoff clamp, and storage sack.

Using The Filter

One thing that I love about the Platypus Gravityworks is that the entire top of the bag opens to fill. No ridiculous small filler openings that are frustrating to deal with. Although one caveat with this type is, that you might have trouble in shallow water. This is because shallow water tends to have more debris can clog the filter. 

After scooping up a desired amount of water to filter, the dirty bag gets sealed via a Ziplock closure. Next you can “snap” the hose to the bottom of the bag and hang the dirty bag. Another bonus is the output tube from the actual filter has a threaded screw top. Which is compatible, with on-the-go Platypus hydration reservoirs. 

Filter Speed or “flow rate” for the GravityWorks filter is 1.75 liters per minute. In the real world this equates to 4 liters in about 2.5 minutes! You will need to back-flush the filter to clean it but this is normal for all water filters.

Versatility

The biggest advantage of the Platypus Gravityworks is the benefit of the two reservoir bags. Providing two 4 liter bags means your backcountry camp actually has 8 liters of water. 4 Liters filtered in the clean bag plus 4 liters unfiltered in the dirty bag. For group camping using it means you don’t have to pack extra water bladders. Another great use for this gravity water filter is as a camp faucet.

One tip: flow can stop if there are air pockets in the clean bag. To fix, open the clean bag to release the air and continue filtering.

Any Disadvantages?

For downsides, I have some personal nuisances but these don’t effect the Platypus Gravityworks performance. It’s a bit heavy and I wish it cost less although in total it’s reasonable for outdoor gear. The Ziplock closure can get gunk in the teeth that needs cleaning, which is a pain.

Next the filter cartridge is prone to freezing, which will render it useless. Store it in the tent with you while you sleep to prevent this. The last problem I have is it doesn’t use activated carbon in the filter. This material filters out chemicals like pesticides and heavy metal out of the water. They do sell a separate device to add but I wish it came standard.

Verdict:

If you love group camping with more than four people, you will love the Platypus GravityWorks filter system. It’s simple to use, reliable and delivers 8 liters of clean water which is amazing.

Versatile 4-Way Use Gravity Filter For Car Camping

Sale
LifeStraw Flex With Gravity Bag
  • Capacity: 3.78 Liters
  • Flow Rate: 1 Liter Per 2 Minutes
  • Weight: 6.94 Ounces
  • Filter Pore Size: 0.2 Microns
  • Cartridge Media / Life: Hollow Fiber With Activated Carbon / 2000 Liters
  • Dimensions: 11 Inches (L) x 5.4 Inches (W)
  • Includes: LifeStraw Flex Filter, 1 Gallon 210 Denier Nylon Gravity Bag, Hose, & Backwashing Syringe For Cleaning
What We Like
What We Do Not Like

LifeStraw Flex With Gravity Bag Review:

Every explorer of the outdoors will recognize this water filter brand. LifeStraw is famous for it’s straw water filter of the same name. For 2021, it’s the best gravity filter for car or RV camping. This is because while it’s adaptable and easy to use, although the system is slow to filter and a bit cumbersome to pack.

The actual system consists of one LifeStraw Flex filter, a 1 gallon (3.78 liters) 210 Denier Nylon Gravity Bag, and a hose. For cleaning the filter, LifeStraw includes a back washing syringe. Although the syringe is weak and for some users has broke while out camping.

Flex Filter With Activated Carbon

Unlike the rest of the filters I review in this article the LifeStraw Flex does use activated carbon. Not only does the Flex remove microscopic contaminants like bacteria and parasites (cysts, E-coli, cryptosporidium). But it also removes chemicals, heavy metals (lead) and micro-plastics. Removing these provide a clear appearance and tasty filtered water.

For ultimate use, you can remove the flex cartridge to use it on its own in 3 ways. Either as a straw filter, as an in-line filter with a hydration pack, or attach it to most disposable water bottles. The main filter lasts for 2000 liters or 500 gallons. While the replaceable carbon element lasts for 25 gallons (94.64 l). Plus the reservoir bag is tough and I never had tearing issues with it.

Disadvantages of the LifeStraw Flex Gravity System

While this system is flexible, it has some performance drawbacks. Lifestraw states the flow rate at 1 liter in 2 minutes, my experience is its slower. Most likely the slower speed is due to the extra activated carbon filter in the system. Tastier water but you have to wait forever to drink it, which isn’t my idea of fun camping. It’s ideal for car camping as I can pack extra water for the first day or two before filtering.

Another nuisance is this system needs a lot of cleaning. You have to back-flush it at least two times a day. You use a syringe to flush the filter which is hard to get right the first couple of times. If I’m out in the middle of the wilderness, the last thing I want to do is extra hard maintenance. Last but not least, the top of the reservoir doesn’t close, if the bag isn’t vertical it leaks, that’s annoying.

Verdict

Get the LifeStraw Flex with Gravity Bag if you camp close to civilization via car or RV. While the Flex filter is super adaptable, the gravity bag is less than perfect. The bag can leak and is bulky to pack. All in all you will get tasty water but you have to be patient as it takes forever to filter.

Best Budget Friendly Gravity Water Filter For Group Camping

green budget friendly label
Sawyer’s 1-Gallon Gravity System
  • Capacity: 3.78 Liters
  • Flow Rate: 3.7 Liters Per 7 Minutes
  • Weight: 8.8 Ounces
  • Filter Pore Size: 0.1 Microns
  • Cartridge Media / Life: Hollow Fiber / 100,000 Gallons
  • Dimensions: 12 Inches (L) x 12.7 Inches (W)
  • Includes: MINI Water Filter, 1-Gallon Bladder Reservoir, Cleaning Plunger, Cleaning Coupling, & Gravity Hose With Adapters
What We Like
What We Do Not Like

Sawyer 1-Gallon Gravity System Review

Are you a budget minded camper looking for a water filtering solution? Try the inexpensive Sawyer 1-gallon gravity bag with dual-threaded “Mini” filter. Sawyer is a popular brand for campers and hikers in 2021 because it’s cheap to buy and performs okay.

In this package you also get a cleaning plunger, coupling, and gravity hose with adapters. In this low price point that’s a great kit that cleans out bacteria contaminants and other harmful pathogens.

Lightweight, Flexible & Easy To Clean

Most distance campers will like that the Mini filter of the Sawyer system weighs 2 ounces (56.69 g). It fits in the palm of your hand, and has a 0.1 micron hollow fiber filter. Performance wise, it removes 99.9% of bacteria contaminants and protozoa like cryptosporidium. Plus it removes 100% of micro-plastic particles. While the 1 gallon (3.79 l) bladder weighs 4.5-6.8 ounces (127.57-192.77 g), dependent on including the hose. The complete system comes in at 8.8 ounces (249.47 g) which is great for trekking long distances to a camp site.

The dual threaded mini filter can detach and users can use it like the Lifestraw Flex filter to drink from a water source. You can screw it onto most disposable water bottles or attach it inline to a hydration pack and bite valve. Made of hollow fiber material it’s encased in a protective case.

Like all filters, the big problem you experience over time is the filter media clogging. The Sawyer come with a plunger that’s simple to use which restores up to 98% of its function and original flow rate. But bear in mind the Sawyer Mini is prone to clogging. Due to the mini having a size of 0.1 microns tiny silts found in water can clog the filter. While cleaning with the included plunger is simple, doing it often becomes annoying. If you choose to camp near shallower water sources this might not be the water filter for you.

100,000 Gallons Filter Life?

Sawyer claims that the mini filter has a 100,000 gallons (378,541 L) life expectancy, sounds great right? Well, unfortunately this is a hard claim for me to trust. In 2015 Sawyer had to change a previous claim that their filter lasted 1 Million Gallons. While the system works, I find it hard to trust a company after these types of claims and corrections happen. You might not though, it’s a personal choice.

Faults of the Sawyer Gravity Bag & Mini Filter

Beyond the cartridge life claims, there are a few issues that Sawyer could improve. First the flow rate is slower than others at 3.7 liters at about 7 minutes. What’s worse is that Sawyer doesn’t give you hanging straps, do you want to hold the bag the entire time? Second, the fill opening is too small, unless you are scooping up water from a deep source it’s finicky to fill. Third, the plastic adapters will split if over tightened, making the hoses useless.

Verdict

Since 1984, Sawyer has manufactured everything from first aid kits to water filters. Which is why many backcountry backpackers and campers trust Sawyer products. If you want a cheap gravity water filter system that may last forever, this is a good system. Keep in mind though if you camp in area with silty water this isn’t the system for you.

Top Blazing Fast Gravity Water Filter For Small Groups

top marks label in blue with yellow check mark
Katadyn BeFree
  • Capacity: 3 Liters
  • Flow Rate: 2 Liters Per 1 Minutes
  • Weight: 6.8 Ounces
  • Filter Pore Size: 0.1 Microns
  • Cartridge Media / Life: Hollow Fiber / 1000 Liters
  • Dimensions: 17.6 Inches (L) x 9 Inches (W)
  • Includes: 3L Reservoir With Filter, Hanging Strap with Carabiners, Quick Connect Hose, On/Off Clamp, & Carrying Bag
What We Like
What We Do Not Like

Katadyn BeeFree Review

This is the fourth generation of the BeFree Series from Swiss-based Katadyn. In 2021, it’s my runner-up pick after the Platypus Gravityworks. The Katadyn BeFree, filters 3.0 liters or 0.79 gallons of drinking water via a 0.1 microns hollow fiber filter.

It provides clean water for 1000 liters of use before replacing the cartridge. Weighing in at 6.8 ounces (192.77 g) it’s the lightest weight model reviewed. This is great for small groups trekking to camps deep in the backcountry. You get a 3 liter reservoir with filter, hanging strap, quick connect hose with On/Off clamp, and a carrying bag.

Like all the others it removes bacterial contaminants and harmful pathogens to deliver clean drinking water. Unlike the other filters though, this one is super fast to clean water.

Rapid Flow Rate

The biggest advantage of the Katadyn BeFree is its ultra-fast flow rate. It’s simple to fill up, due to the HydraPak 3.0L reservoir having an integrated “Bail and Carry” handle. You hold the small bail arm and scoop up water into the reservoir bag. Next, keep hold of the bail with one hand and screw on the filter hose to the bag. Now you can flip it right side up and attach the reservoir hanging straps if you hadn’t already. Ensure the on/off clamp on the hose is in the closed position to stop any flow of water.

After you hang the reservoir bag, open the clamp. As filtering begins you will see the swift flow rate, it filters 2 liters per minute! As a result, campers who need instant hydration can rely on this gravity water filter.

Cleaning Katadyn Water Filters

If the BeFree water filter clogs or the water flows slow it means the filter needs cleaning. Unlike other brands which use back flushing to clean filters, Katadyn uses unique method. Called “shake-to-clean” you shake or swish the filter underwater to dislodge debris.

Downsides Of The Katadyn BeFree

While the flow rate is great and the operation is simple, there are a couple downsides to this water filter. First the plastic carabiners that attach the straps to the reservoir are flimsy. Overtime other users complain about them snapping. Second, the fill opening is small which does make filling in shallow stagnant water hard. Third and last, you have to clean and dry the system 100%, if you don’t the hoses fail. Which is a nuisance if you are out camping with a couple thirsty people.

Verdict

If you are camping with a small group that wants clean drinking water fast, the Katadyn BeFree is the best choice. It’s simple to use and clean but time will tell if it’s tough enough for you.

Best MSR Gravity Filter For Groups Of 1-2 People

MSR Trail Base
  • Capacity: 2 Liters
  • Flow Rate: 1 Liters Per 1 Minutes
  • Weight: 16 Ounces
  • Filter Pore Size: 0.2 Microns
  • Cartridge Media / Life: Hollow Fiber / 1500 Liters
  • Dimensions: 12 Inches (L) x 5 Inches (W)
  • Includes: 2-Liter Dirty Water Reservoir, 2-Liter Clean Water Reservoir, 1 Trail Shot Filter, Easy-Pour Cap, & Connection Hose
What We Like
What We Do Not Like

MSR Trail Base Review

Many outdoor enthusiasts swear by MSR products for their outdoor gear and I like most of their stuff too. The brand is under the global envelope of Cascade Designs which also owns Platypus Gravityworks. As a buyer, I expect the quality of the MSR Trail Base to match the Platypus Gravityworks 2L. Yet it falls a bit short in performance based on its hefty price.

3-In-1 Use

What is good about the MSR Trail Base is its 3-in-1 use. The package is basically the MSR trail shot filter with a couple 2 liter bags and a hose. Use it as a gravity system at camp, a pocket-sized filter on the trail, or an on-the-go bladder with drinking cap.

Like all the others the filter is a hollow fiber material rated at 0.2 microns. As a result it removes 99.9% of contaminants like bacteria, protozoa and debris in the water. But don’t expect it to fight viruses like Hepatitis A or Norovirus.

The actual set up of each use is quick and easy. It has a good flow rate of 1 liter per minute with a filter life expectancy that matches the Gravityworks (1500 L). To clean users need to back-flush the trail shot filter, you can follow my cleaning guide to do the bags and hose.

2 Person Capacity

Where the MSR filter system falls short is the capacity of 2 liters per bag for a total capacity of 4 liters. This smaller amount of water is capable of hydrating at best 2 backcountry campers. This isn’t a fault of the system, for my review I had the 2 liter version. For the extra price you should get their 4 liter model.

For this model though, it’s a decent option for small groups but not as great as the Katadyn BeFree. This is due to cost, plus the Befree holds more, even if it lacks a clean reservoir. Buying extra reservoir bags aren’t that expensive.

Downsides of the MSR Trail Base

The worst thing about the Trail Base is the price and its weight. It’s far more expensive than all the others except for the Platypus Gravityworks. The reason for this is beyond me but MSR does make premium products in other outdoor spaces. Next it’s the heaviest system tipping the scales at 16 ounces or 1 pound. For the person carrying an extra pound in their pack it becomes noticeable quick.

Other issues other users found are the bags and hoses are hard to dry, which leads to future failures. Plus some people complain of a weird plastic taste, I didn’t in mine, but who wants terrible tasting water?

Verdict

If you’re hiking, or base camping with two people, only trust MSR products and the price is fine for you, buy this filter. It has flexible use but you have to pay a premium and carry a heavy system. For me I prefer to pay less and carry less weight in the backcountry.

3 Considerations For Best Gravity Water Filters

For those of you new to wilderness group camping it can be difficult to know what to buy. To help I have laid out three big factors to picking the right gravity water filter for your needs. They are as follows:

1. Capacity

This is the main factor for group camping, it’s the volume of water the filter is capable of cleaning. Single bag systems filter less contaminated water than 2 bag systems like the Platypus Gravityworks.

2. Flow Rate

A flow rate is the through put or speed a water filter can clean water through the filter media. The faster you can filter water the better, especially in hot climates.

3. Weight

This is the weight of the device, at empty. It’s important because you have to carry it and other gear to the campsite. Sometimes over a long distance if camping in remote areas.

Step by Step Cleaning Your Gravity Water Filter

To prolong your new gravity water filters’ life expectancy you need to clean it. Cleaning your gravity filter will stop the growth of mold and help restore flow rate. You need to disinfect the filter before and after long-term storage. Long term storage equals at least two weeks.

Some manufacturers give you specific cleaning components like syringes while others provide none. It’s best to follow any instructions you get for methods of cleaning if there are special parts. For models that don’t come with special cleaning parts, below is a simple step by step cleaning method.

1. Disconnect the hose (attached to filter) from the dirty reservoir and clean reservoir. Flush both the dirty bag and clean bag with tap water. After reconnect hose to dirty bag and move on to next step.

2 a. Fill a container or the dirty reservoir with 2 liters of distilled water. Next add either 2 chlorine dioxide purification tablets or 2 drops of bleach.

2 b. Pour container solution into dirty reservoir.

3. Swirl the diluted bleach solution in the dirty reservoir bag for a minute. Hang up this bag and let the entire amount of solution flow through cartridge (into sink or container). Use the same process as removing water contaminates.

4. Disconnect the filter from the hose and back flush with clean distilled water. After shake out the filter or I like to use a blow-dryer set on low to dry out the filter.

5. Using long bamboo skewers or other material prop both reservoir bags and hose then allow to dry 100%. Time wise, this can take many days.

6. Store the entire system in its carry case in a heated area to prevent freezing.

Benefits & Precautions For Gravity Water Filters 

The obvious reason to choose a gravity water filter is to keep hydrated. Proper hydration is critical for your health and enjoyment while camping. But using a gravity water filter has many other benefits, such as the following:

  • No need to carry a heavy water filter while exploring around camp. Remember water is heavy, about 8.3 pounds (3.76 kg), that’s a pain to lug around in your pack. Not having clean water limits the areas you can camp.
  • Other than hanging the reservoir, the water filter system is effortless. It doesn’t need any power to operate or effort. Fill the dirty bag and let gravity do the work.
  • Gravity filtration is a simple and efficient process that makes little to no noise. Let it work while you sleep in the tent.
  • Less internal mechanical parts equal fewer problems compared to complicated pump filter systems. Nothing is worse than a seized pump filter while camping.
  • Easy maintenance. You do need to back-flush the filters and clean the system for storage. But other than replacing a filter cartridge before heading out, cleaning is easy.
  • Don’t have to pack batteries as gravity filters don’t use them.

Precautions For the Best Gravity Water Filters

Bear in mind, your new water filter can be at risk of contamination over time if the filter gets damaged. Filters that get damaged let harmful pathogens bypass the filtration, rendering it useless.

Look for gravity filters which consider future damage and protect against it. Better brands provide a special housing around the filter, protecting it from impact. I recommend you take an extra filter with you on long trips out in remote areas. Nothing is worse than being out in the middle of nowhere without clean drinking water.

Remember to back-flush and clean the gravity filter to reduce clogging the filter. Clogging slows the flow rate and over time damages the filter. Another cleaning tip is to ensure to clean the spigot attachments because mold can build up inside this part.

In Summary

All things considered, you should be able to make an informed choice of which gravity filter to buy. If group camping in a large group, you want to focus on total capacity. For camper who want a multi-use filter there are options for you. For small groups you can rely on fast flow rates and weight. If you are sensitive to taste, look for options with activated carbon. This material stops impurities such as chromium and herbicides from passing through into the clean water. Whichever model you pick, each will reduce the risk of waterborne pathogens and provide safe drinkable water.

Thank you for allowing Outdoors Informed to help with your research. We do it to help you spend less time indoors and more re-hydrating after a fun day of camping.

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Last update on 2021-04-09

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