Turning Streams into Reliable Water Sources
Portable water filters make it possible to safely refill from streams, springs and other natural water sources during long rides and outdoor adventures.
Water covers about seven tenths of our planet. Yet the share that is actually available for drinking is surprisingly small. On a long ride, that reality becomes impossible to ignore.
The Katadyn BeFree AC Bottle Portable Water Filter
Beautiful, long and hot days are approaching. You're preparing for an epic ride - maybe a mountain bike adventure, a gravel route, a classic bike-packing trip or a long road journey into the unknown. Gear starts piling up. Some goes into bags or a backpack, some into your jersey pockets, some onto the bike itself. Yet one question always remains the same: where do you put the water? And more importantly - how much water do you actually need?
Proper hydration while cycling is important not only for keeping thirst at bay but also for maintaining physical performance. During prolonged activity, we lose fluids and minerals through sweat, which affects power output, concentration and endurance. Even mild dehydration can reduce performance, slow reaction times and increase fatigue. Studies often mention a threshold of around 2% body mass loss - for a 75 kg cyclist, that's roughly 1.5 litres of fluid. By that point, your body is already making its objections quite clear.
Since water covers roughly seven tenths of our planet, drinking should not be a problem in theory. In practice, however, the story is a little less romantic. Around 97% of all water is saline, while most of the remainder is locked away in glaciers or deep underground. Easily accessible drinking water is surprisingly scarce. In Slovenia, we're fortunate enough to turn on a tap and drink. But what happens when you're in the middle of a long ride and there's no shop, house or mountain hut nearby - only a stream, a spring, a lake ... or an overly optimistic puddle?
That's when water filtration starts to make sense.
Portable Water Filter in a Cycling Bottle
A few years ago, I tested the Katadyn BeFree filtration system with a soft flask. Now the Swiss company has introduced a version that's much more cyclist-friendly.
The system consists of a cycling bottle and a lightweight portable water filter available in two sizes (0,7 L and 0,95 L) and a filter with a drinking nozzle that simply screws onto the bottle.
In today's world, there is already enough complexity. The Swiss engineers decided to simplify things for themselves - and even more importantly, for us. They mounted the filter onto an Elite bottle. This means the filter can also be used with other Elite bottles, including smaller 500 ml versions. Unfortunately, the thread is not compatible with Elite's metal bottles or insulated flasks. Apparently, physics and industry standards have their own ideas.
How the Portable Water Filter Works
The most important part of the system is, of course, the filter itself.
Swiss company Katadyn has been developing portable water treatment solutions since 1928. The BeFree filter consists of two main components. The first is the cap with the drinking nozzle and a hollow-fibre filter that removes 99,9% of protozoa and 99.999% of bacteria, microplastics and other particles larger than 0,1 μm.
These filters do not remove viruses, so that puddle in the middle of a cattle pasture may not be the most refreshing option after all.
The second component is an activated carbon insert that sits between the main filter and the drinking nozzle. It slightly reduces flow rate but helps remove unpleasant odours and improves taste. The system is not designed for desalination either. Katadyn has other, considerably more maritime solutions for that purpose.
Maintenance is straightforward. The main filter is rated for approximately 1.000 litres of water and only requires occasional rinsing with clean water. The activated carbon insert remains effective for about six months after first use and then needs to be replaced.
Real-World Testing
Last week, I completed a long two-day gravel ride through the forests of Inner Carniola. It was hot, settlements were few and far between, and I refilled from streams several times.
I'm still alive.
For this type of experiment, that remains the primary measure of success.
On the bike, I carried two 500 ml bottles. Because of my frame bag, larger bottles simply don't fit. One bottle contained an isotonic drink, while the other contained plain water fitted with the Katadyn BeFree filter.
When I emptied the first bottle, I filtered water from the second bottle into it and only then added the isotonic powder, which I carried separately in a small container. At the next opportunity, I refilled the filtered bottle from a stream - or from a tap if I happened to reach one first.
In practice, the system worked brilliantly.
Streams became my mobile water stations, and I always had access to fresh water. The forests became even more welcoming because, in addition to climbs, they also provided cold drinking water.
Everyday Use
If you only want water, you can drink directly through the nozzle at the top of the filter. It is protected by a small cap that helps keep it clean on dusty roads.
That's useful when you've spent several hours riding through a cloud of dust created by the group ahead of you. It's also mildly amusing when you think about all the dust you've probably swallowed during countless gravel rides anyway.
The BeFree filter is not only useful for cyclists. Hikers, travellers and anyone who enjoys venturing a little farther from civilisation will happily find space for it in their pack. It can even earn a place on an office desk - especially in locations where tap water doesn't exactly taste like it came from an Alpine spring.
Competitive riders may complain about the slightly slower flow rate. For everyone else, the water flows quickly enough.
Especially when you're really thirsty.
About the Author
Matej Hartman is a Slovenian mountain bike guide, outdoor writer and founder of MahMTB. Through his writing and guided tours, he shares practical knowledge, route ideas and real-world experiences from mountain biking, gravel riding and bikepacking adventures across Slovenia and beyond.
Read more at mahmtb.com
About Lyocorner
Portable water filters are an essential part of modern bikepacking, hiking and self-supported travel. At Lyocorner, we publish guides, reviews and practical field experience covering portable water filtration, hydration strategies and outdoor nutrition.
Our goal is to help outdoor enthusiasts choose the right portable water filter, understand its limitations and confidently use natural water sources during their adventures.
Frequently Asked Questions
Some do, some don't. The Katadyn BeFree featured in this article is designed to remove bacteria, protozoa and particles, but not viruses. Katadyn also offers portable water purifiers, which are designed to reduce viruses as well as bacteria and protozoa.
The main hollow-fibre filter is rated for approximately 1,000 litres of water, depending on water quality and maintenance. The activated carbon insert remains effective for around six months after first use.
Yes. A portable water filter can significantly reduce the amount of water you need to carry and allows you to refill from streams, springs and other natural water sources during long rides.
No. The Katadyn BeFree AC bottle filter is compatible with selected Elite plastic cycling bottles but is not compatible with all bottle types, including most metal bottles and insulated flasks.
No. Portable water filters are widely used by hikers, backpackers, campers, travellers and anyone spending time away from reliable drinking water sources.