What Is the Best Portable Water Filter for Survival?

Platypus Gravityworks

For a lot of backpackers, gravity water filter systems were a revelation. Imagine — no more tired hands from all the pumping! The Platypus Gravityworks is one of two awesome gravity filters in this review and suffice it to say, it and the MSR Autoflow did not disappoint.

Filter Lifespan:

1,500 liters

What People Are Saying:

189 reviews on Amazon with 91% 4-5 star ratings

What we love about the Platypus is that it’s got two reservoirs, one for dirty water and another for clean, filtered water. That means you can store and carry clean water back to camp with you.

Large volumes of it, too, as the Platy is available in 2-liter and 4-liter systems (we used the 2-liter system for this review). It’s great for big groups or if you’re going on a long-haul trek with a few rest stops in between. Both reservoirs are made of plastic — tough but flexible — and can easily be cleaned and then rolled for storage.

What we didn’t love about it is that it has a lot of little parts. Literally a small issue in the grand scheme of things, considering that the Platypus is an excellent water filter, but when you’re out in the backcountry assembling a filter with so many tiny accessories, it can be a chore. Be that as it may, these little parts include the various adapters that allow you to use your Platy filter in many ways, so you just have to be organized on the trail to avoid contaminating your adapters.

The dirty water bag is secured by a ziplock top. It can be quite difficult to close or even open the bag once you’ve filled it to capacity or after multiple uses. The bag itself, however, has sturdy straps. You can use those to hold the bag up or hang it on an elevated place, like a tree branch.

Its manufacturers proudly state that the Platypus can filter 1.5 liters per minute. It had been raining further upstream when we tested the product, so the water source was, at best, the color of fresh latte. All the better to put the products to the test.

The Platy worked at a decent speed, but it wasn’t what we expected. In our experience, we got about 1.75 liters in 2 minutes — that’s barely a liter at half the time. On the plus side though, it consistently delivered the same volume after repeated use and didn’t slow down.

The system can be cleaned right on the field through backflushing, which was a breeze. Other product reviews state that they have a bit of difficulty with the backflushing, but as per our experience, it was quick and easy. It took about 3-5 minutes of continuous backflushing before the water turned clear again.

The Platypus Gravityworks can be used to filter 1,500 liters of water in its lifetime.

All in all, the Platy did great. Its clean water reservoir was convenient, and it made backflushing easier.

MSR Autoflow Gravity Filter

The second gravity filter in this review is the MSR Autoflow and it met expectations with flying colors.

Filter Lifespan:

1,500 liters

What People Are Saying:

Only 2 reviews on Amazon but both for 5 stars

Unlike the Platypus, the MSR doesn’t come with a clean water reservoir, which could be a pro or con however you look at it.

This means that you’ll have to provide a clean water container of your own, which could be a water bottle or a hydration bladder. The kit does have adapters for both, so it’s not a very big problem.

While having a clean water reservoir like the Platy does have its benefits, you’ll also have fewer small parts to deal with, which makes set-up faster and easier. Either way, it doesn’t discount the fact that MSR’s performance was great.

What we love about it is that it filters really fast.

It’s advertised to filter an impressive 1.75 liters per minute. In our experience, we got about 1.5 liters a minute, which wasn’t far off the mark. It yielded the same volume after multiple uses.

The MSR’s dirty water reservoir not only looks sturdy; it feels like it too. The reservoir’s texture has a bit of bite and won’t likely slip from your hands when you’re gathering water from a fast-running source. We loved the fact that you can secure it using a buckle instead of a ziplock because a buckle is less prone to pop open.

Backflushing, however, can be a bit challenging because the MSR doesn’t have its own clean water reservoir. You certainly can’t backflush properly if you’re using a wide-mouthed bottle or a container that’s not compatible with the MSR’s adapters.

In our case, we used the Platy’s clean water reservoir together with the MSR’s bottle adapter to gather the filtered water. Thankfully, it was a perfect fit between the two. We had a bit of trouble on the first attempt and had no flow at all. The second try yielded better results. We had a clear flow in about 2 minutes of continuous backflushing.

All in all, the MSR is the faster filter on this list, but you gotta make sure that you have a compatible clean water reservoir for backflushing.

Lifestraw

Any self-respecting backpacker or prepper would recognize what a Lifestraw is. This light and slender personal filter was originally designed to give developing countries access to clean drinking water. It was also meant to be used as an emergency filter in disaster-stricken areas, but it has since become a staple in many preppers' BOBs.

Filter Lifespan:

1,000 liters

What People Are Saying:

4,082 Amazon reviews with 94% 4-5 star ratings

Since it’s so portable and relatively cheap, the Lifestraw quickly gained popularity in the backpacking and prepping communities.

And boy, is it portable.

At only 2 ounces, the Lifestraw is exceptionally light and easy to carry around. It takes little space in a bag, making it great for people who are always on the move, like backpackers or hikers.

The Lifestraw is also ideal for preppers who want a personal filter in their bug out bag or survival kits. It even comes with a lanyard so you can wear it around your neck. The lanyard itself, however, doesn’t look sturdy enough and if we’re being honest, you’re better off replacing it with a length of 550 paracord.  The 550 is more reliable and is something that you can deploy as cordage when the need arises.

The filtration process is pretty straightforward. Unlike other water purification devices, you don’t have to wait for your water to be filtered via gravity or pump. You simply have to find a source (be it a river, stream or puddle) and drink from said source using the Lifestraw. More often than not, it results in going on your hands and knees to take a sip from a body of water, which can be messy or inconvenient. You’d also need a couple of strong sips to get started, so sipping from a shallow water source is tricky.

What’s great is that this device is effective against 99.999% of waterborne bacteria, protozoa, parasites, and particulates and can effectively filter as much as 1000 liters of water — enough for one person for a year. Cleaning it is also simple: all you gotta do is puff out of the filter to expel any nasties that might block it.

And that’s the thing about the Lifestraw.

The simplicity of its design is also its biggest downside. While it’s understandable that the straw was meant for urgent needs and short-term crises, it doesn’t discount the fact that, well, it’s pretty limited.

First of all, it’s a personal filter: you can’t use it for big groups or if you’re bugging out with the family. You’d have to get one Lifestraw each and even then, you still will be unable to store and bring clean water with you.

You’d always have to be on the lookout for a water source to drink from, or, as an alternative, lug around unfiltered water in a container with an opening wide enough to accommodate the Lifestraw. You will also be unable to filter water for cooking and other purposes. Using the Lifestraw is pretty okay if you’re staying in one place, but if you’re hiking or camping out? Not so easy.

All in all, the Lifestraw wins in terms of portability. It’s pretty handy to have in emergencies as a personal filter. But if you’re a big group that would consume and store large amounts of water at a time, you might want to look at the other water filters on this list.

Katadyn BeFree Water Filter

The Katadyn BeFree water filter is like the lovechild of the Lifestraw and the Platypus. You can easily bring it anywhere you go and it actually carries water. Pretty neat, huh?

Filter Lifespan:

1,000 liters

What People Are Saying:

84 Amazon reviews, with 73% 4-5 star ratings

The Katadyn BeFree filter is portable like the Lifestraw. The flask is collapsible, so it won’t take up too much space in your bag. It can even fit in someone’s back pocket, so it’s great for lightweight hikers, backpackers, and runners. Like the Platy, you can actually carry water with you. Sure, it’s nowhere near the Platy’s 4-liter max capacity, but anyone knows that a little hydration goes a long way when you’re on the trail.

The Katadyn BeFree is pretty easy to use. You don’t need a complicated set-up, and you can have a drink of water in a jiffy. The filter is attached to the drinking nozzle, so all you have to do is get water, attach the filter, and squeeze. Just make sure you don’t contaminate the nozzle’s tip.

Filter size is at 0.1 microns, so it’s effective against most waterborne bacteria, protozoa, and parasites but won’t do much against viruses. When the filter has already reached its lifespan, you can simply buy a new one. The reservoir itself has a great texture for grip; although it is quite smaller than most, it doesn’t easily slip from your hands, especially when you’re gathering water from a running source. While the reservoir can only carry 1 liter of water at a time, you can use the filter to easily fill up other containers with clean water.

The disadvantage of the Katadyn comes in when it’s time to clean. You can still clean it on the field — you basically fill the bottle with water and shake it clean, or take the filter out and swirl it around freshwater to clear it up. Obviously, unlike gravity filters, you can’t do any backflushing to ensure the quality of the filter. Washing it horizontally can also damage the filter.

Another disadvantage is that the filter is not compatible with a lot of water bottles. You need to be careful not to break or puncture the bottle, or the filter will be of little to no use unless you buy a new one. Take note that the Katadyn BeFree doesn’t come in cheap — it costs about twice as much as the Sawyer Mini, which we’ll discuss in a bit.

All in all, the Katadyn BeFree is great for personal use. It just came out on around August 2016, so its technology is still pretty new. That being said, it’s prone to have some growing pains in the R&D department, like issues about quality control and field failures that need to be addressed. It’s pretty great when it works, but it could be a pain in the butt when it suddenly stops working.

Sawyer Mini

Last but definitely not least, we have the Sawyer Mini, which blew all other personal filters out of the water (forgive the pun). This water filter is tiny, but it's a beast in disguise with its backflushing capacity.

Filter Lifespan:

100,000 gallons

What People Are Saying:

4,082 Amazon reviews with 94% 4-5 star ratings

You can tell that Sawyer really put their back into this water filter.  It’s so small that it can fit in the palm of your hand, but here’s the kicker:

It can filter up to 100,000 gallons with its backflushing capability.

Let that sink in.

For comparison, the Lifestraw, which is slightly heavier than the Mini at 2 ounces, can only filter 1000 liters or 264 gallons.

There are a lot of things to love about the Sawyer Mini.

First, it’s so versatile. It comes with a sturdy pouch that you can attach to the filter, allowing you to take the water wherever you go. The reservoir is also collapsible, so you can roll it up when not used.

You can drink directly from the reservoir with the filter attached, or you can use the system to filter water into other containers. Yes, it can be used to filter several bottles of water, although it’s not as efficient compared to the gravity filters featured in this review.

Next, the system comes with a straw, so you can also use the filter to directly drink from a water source, the way you would with a Lifestraw. The catch is that you won’t necessarily have to get down and dirty. The Sawyer Mini can be screwed on most plastic water bottles.

As long as you can squeeze the bottle, you can definitely drink from it. This is the usual problem with many water filters, and we are so glad that Sawyer came up with this solution.

Another advantage is that you can also use the Sawyer in line with your hydration bladder.

The kit comes with a syringe that you can use to backflush the filter.

Perhaps the only disadvantage to the Sawyer Mini is that the pouch can’t carry more water. It can only hold 16 ounces at a time, so filtering large amounts of water can be exhausting after a while. To be fair, though, the Sawyer Mini was designed as a personal water filter. And there’s definitely a workaround for it, too. Since the Mini can be screwed onto most plastic and soda bottles, you can simply replace the pouch with a bigger reservoir.

All in all, the Sawyer Mini ended up being the best of the bunch, thanks to its versatility and excellent price-performance ratio. We highly recommend it to anyone who loves the outdoors.