I spent many years as an engineering research scientist in a university environment. One of my favorite research programs that I managed included a number of multi-year portable water treatment technology and water quality studies, in the context of backcountry recreation, military deployment, and disaster relief.

It was during these years where I learned to despise portable water filters for their weight, slow treatment times, effort (arg, the pumps!), ease of clogging, and difficulty of cleaning.

It is because of these disadvantages that I’ve learned to love ultralight treatment technologies like tablets and chemical kits.

Filters of course have evolved through the years. We’ve seen lighter pump filters, gravity filters, inline filters, and filter bottles.

But not until the introduction of the new Katadyn BeFree Water Bottle Filter have I experienced a (truly) lightweight filter option that treats water as fast, in a package so compact. The 0.6L bottle is about a 2-oz package (2.5 oz is the approximate wet weight that I measured, which includes residual water from a treatment cycle), and it comes in a larger 1.0L size and a gravity filter model as well.

Watch the video to see my brief commentary about the filter and what I think about its throughput using clean water. Stay tuned for a more comprehensive review – I’m using this as my primary water treatment technology this summer and fall.

YouTube video

The Katadyn BeFree Filter Product Line

Weight: 2.1 oz
Price: $39.95

The larger, 1-L version.

Weight: 2.7 oz
Price: $44.95

The smaller, 0.6-L version.

Weight: 3.5 oz
Price: $69.95

A gravity flow version for larger water volumes / groups.

Weight: 1.5 oz
Price: $24.95

Replacement cartridge...or...a DIY part for the innovative MYOG'er!


  • Filter medium: Hollow fiber membrane with 0.1 micron effective pore diameter;
  • Filters bacteria: yes (99.9999%) | protozoa: yes (99.99%) | viruses: no
  • Flow rate: 2 L/min
  • Bottle opening: 43mm
  • Longevity of filter cartridge: 1,000 liters

Compared To…

As I mentioned in the video, I’ve been partial to a chemical kit (Aquamira) for many years. Its “durable” (no mechanisms to fail), imparts minimal taste (and actually improves the taste of nasty water sources), is light, doesn’t fail when freezing (filters can crack), and is simple to use. There’s still a wait time with Aquamira (on the order of 15-30 minutes depending on the quality and temperature of your water source).

I’ve also used Steripens and gravity filters in various contexts. There are a lot of different ways to treat water in the backcountry!

Weight: 3 oz

Chemical water treatment kits like Aqua Mira are the gold standard among ultralight backpackers for their ease of use and reliability.

Weight: < 1 oz

Water treatment tablets are the lightest option, but they take more time to effectively treat water. Least expensive option for 1-time purchase.

Weight: 2 oz

Straw filters are light and convenient, but with a low volume filtration surface, can clog early if the water is silty.

Weight: 8-16 oz

Gravity filters are low-maintenance options that are great for groups, because they can reliably filter large volumes of water. Most expensive option.

Weight: 3 oz

If efficacy is your primary criteria, then get a UV pen like this. UV light disinfects all types of organisms (including protozoan cysts and viruses), and does so rapidly (1 minute treatment time).

Disclosure: some of the links above may be affiliate links, which means if you place an order at one of these retailers, we receive a small commission on this sale. This helps support Backpacking Light, thank you!

Related Links / Mentions:

Also check out this forum topic at Backpacking Light discussing other user’s experiences with the Katadyn BeFree!