This Top Pick for lightweight travel is a perfect option for those seeking a filter that fits right inside of a bottle. The soft bottle it comes with is collapsible, making it easy to pack away and store. Like most soft containers, its durability isn't the greatest, but the screw top filter is compatible with other soft bottles that you can stash with you. A favorite amongst long-distance trail runners and the like, it's perfect for solo on-the-go filtration.
Performance Comparison

Eddy runs it out early Fall way in the high country. Even though water sources are scarce, this lightweight filter keeps us hydrated while on the go.
Credit: Amber King
Water Quality
The Katadyn BeFree protects against bacteria and protozoa; however, it does not remove viruses. It should be adequate for most streams in the US and Canada.
The filter does remove odd tastes and does a great job of producing fresh, clear water. It features a hollow filter design with a 0.1-micron pore size. The filter is short with big open spaces and spindled tubes that are latticed overtop of one another. This design makes for quick guzzling on the go. It does well for all sorts of water sources from turbid to clear.

A look at the profile and size of the lightweight and effective filter used in this system.
Credit: Amber King
Durability and Maintenance
The filter and screw-top it's attached to is quite durable and lasts for roughly 1000 liters before needing replacement. However, the soft bottle is a different story.
If you're a runner or use soft bottles often, you'll know that it's hard to find a durable soft bottle in general. This bottle is no different. Online, several reviews say that the storage bottle burst on them at the seam around the rigid top collar piece after only a few uses.

The area where the bottle attaches to the neck or collar area is prone to ripping.
Credit: Jessica Haist
We have not experienced it bursting, but after testing five of these bottles, each one has eventually sprung a pin-prick leak. In one case, these pin-prick leaks occurred on the first time out. These bottles are delicate and aren't very durable. While our experience didn't yield a filtration system that didn't work, it's possible that it might happen. If you plan on going long distances with this as your only filtration system, we'd recommend carrying a second soft bottle in case the first one does leak or break. You can also carry a more durable bottle option, as seen in the picture below.

This shows the Katadyn bottle top filter attached to a different, more durable soft bottle that also comes with a 100% lifetime guarantee. An awesome feature of versatility that we love.
Credit: Amber King
In terms of maintenance, it's pretty easy. You can easily clean out the filter by running water through it and swishing it around. Overall, this filter does not have the most durable soft bottle. If you plan on getting it, be sure to purchase a second soft bottle that you can use in case it does spring a leak on the trail

The EZ clean membrane is easily cleaned. Simply swish it around in a water source and continue on your way. This filter and top are compatible with other soft bottles as well.
Credit: Amber King
Treatment Time
For an on-the-go filter, it is super fast. Just fill, sip, and move on. Instant water on the trail.

The wide nozzle provides a quick flow that makes drinking from it nice and easy.
Credit: Amber King
Weight and Packability
As an extremely packable and lightweight filter, it is our favorite option for activities like trail running or mountain biking where soft bottles are a huge plus. It weighs only 2.1 oz with both the soft bottle and mini filter inside. The filter itself is fairly short, making it easy to fit inside of a variety of compatible soft bottles.
When your water is gone, you can collapse the bottle and tuck into an area that'll fit into the palm of your hand. No other bottle filtration system has a profile that is as short, saving space in the bottle, and allowing you to fit more water and collapse the container more effectively.

The shorter profile of the filter allows this bottle to collapse to a tiny volume, making it ultra packable and lightweight.
Credit: Amber King
It fits comfortably inside the front pockets of a trail running vest. Again, if you have a bottle that you prefer, check to see if the top is compatible with your favorite soft bottle.

A look at the lightweight profile of this fantastic niche filter.
Credit: Amber King

The BeFree is a great choice for a day out where you don't want to carry a lot of water.
Credit: Jessica Haist
Ease of Setup
Setup is pretty darn straightforward. Out of the box, it's ready. Scoop up water and screw on the top.
While this is a great setup, getting water from super shallow water sources is a little limiting. Since you have to scoop water into the bottle, you might have a hard time getting water from super skimpy and shallow sources. However, it works for most cases.
Ease of Filtration
Another super easy and straight forward process. The water filters through the hollow filter easily. Of all the "sucking" or "squeeze" designs, this is one of the easiest to use. Other filtration systems with a similar method take lots of effort to suck through the filter. When drinking from the Katadyn BeFree 0.6L, water flow is steady and easy to get. We even drank from this bottle just around the house because it wasn't cumbersome or annoying to use.
This system suits on-the-go travel. You can try to squeeze water through and put it into a larger storage bottle, but that takes a little more time and energy. Other sizes are available if you need more capacity than the 0.6-liter version we tested. Overall, this is our favorite on-to-go system because of how naturally water flows through the body of the filter to your mouth.

Providing instant drinking BeFree needs a bit of air in the bottle to squeeze out all the water.
Credit: Ian McEleney
Value
The Katadyn BeFree is a little on the expensive side but does offer optimal performance. The bottle's durability issues may have you being super careful if you want to optimize its 1000 uses. We recommend buying a second soft bottle as a back-up if you don't have any other filtration system handy.

Run, hike, explore! This lightweight filtration bottle is perfect for long days on the trail.
Credit: Amber King
Conclusion
This Top Pick is ideal for the traveler seeking a super lightweight and on-the-go filtration system. While it's not the most durable, it offers a fast flow rate that filters bacteria and protozoa including Giardia and Cryptosporidium. The soft bottle is collapsible, fitting easily into the pocket of a hydration pack or vest. It's compatible with other soft bottles, adding to its versatility.

Taking a break on a hiker, we take a moment to enjoy a cool sip of water...upstream of obvious water contaminants.
Credit: Ian McEleney