There are many micro-filters on the market. The Katadyn BeFree remains a great favourite for Three Points of the Compass because it is light, compact, easy to use, easy to clean and, most importantly, it works.
Swiss based Katadyn have over 50% of the market share in portable water treatment technology for hikers, campers and the marine industry. Some of their brand names may be familiar- Micropur, Steripen and BeFree. The first is chemical treatment, the second uses UV technology. Since 1952, Katadyn has also been developing and producing mobile water filters that utilise either ceramic or a glass fibre filter fabric. This fabric has 0.2 μ pores (0.1 micron, or, 0.0001 mm), which is smaller than protozoa and bacteria and can therefore filter them out. These are commonly found in water and can cause disease if water is not treated.
The BeFree relies on glass fibre technology housed in an ‘EZ-Clean’ membrane. The channels in this open plastic frame allow more water to flow to the hollow filter fibres, which improves flow rate, and allows filtered sediment etc. to be more easily swished away afterward. I could simply boil water to kill off errant organisms however this will not remove sediment and uses considerably more fuel if I relied on it for purifying all my drinking water.
BeFree filters are manufactured by Katadyn Products Inc, Switzerland who released this product to general sale in September 2016. Three Points of the Compass first purchased a Katadyn BeFree filter in 2017 and one has been included in the gear list for most longer trails ever since. The filter cartridge alone weighs 34g (dry weight) and is 108mm long, though the great majority of this length is actually inside the waterbottle/flask/bladder when in use. The BeFree has a screw diameter of 42mm and a rigid plastic outer neck of 49mm diameter. It is this neck that is held to screw it on and off a soft flask.
The 42mm thread is only compatible with bottles and soft flasks that have this quite wide screw thread. The BeFree is primarily a squeeze filter so requires soft sided water holders in order to squeeze water through it. The wide neck diameter is enough to discount it for many hikers and backpackers as the lack of compatibility with standard shop bought bottles simply does not fit their preferred hydration ‘system’. The wider neck size is a growing standard however and for those that have made the switch, or are prepared to, this filter may suit. The wider 42mm opening does make a softflask or bladder far easier to fill from a stream etc.
The BeFree filter is advertised as meeting the standards required by the US Environmental Protection Agency to be described as a micro-filter. These are- removing 99.9% protozoa and 99.9999% of bacteria including Cryptosporidium, e-coli and salmonella. In excess of these, the BeFree actually demonstrates 99.999% and 99.999999% removal rates, respectively, in difficult to find lab results. Two of the commoner water borne protozoa are Giardia and Cryptosporidium. Both may be familiar to backpackers, if not personally, then by reputation. Both are larger in size than the pore size in the hollow fibre membranes found in most squeeze, inline or gravity filters so are filtered out. In common with similar micro-filters such as the Sawyer Squeeze, LifeStraw and HydroBlu, the BeFree filter will not remove viruses. It is for this reason that these filters cannot be described as water purifiers.
The BeFree has a life expectancy of up to 1000 litres of water, dependant on water quality. This means if constantly used for filtering particularly turbid water, then the 1000 litre capacity is considerably reduced. I have seen pre-filters advertised that can be slipped over the BeFree filter body, but have never found them available to the UK market. Which may be just as well as many reviews state that once attached, the filter will not fit in the neck of most HydaPak flask and bottle options. So pretty much useless.
The BeFree filter can be purchased in a variety of formats, almost all are simply which bladder or flask it is paired with. HydraPak bladders are the usual chosen partner when purchased as a unit. In the UK the collapsible PVC and BPA free 0.6lt SoftFlask has long been the usual smaller option. Larger SoftFlasks from HydraPak were more usually seen paired with the filter in Northern America- 1.0lt and 3.0lt as standard but have since become more generally available.
With a bit of searching most pairing options can be purchased just about anywhere. To compliment these, HydraPak have an ever expanding line of soft bottles, flasks and bladders with a 42mm thread capable of being paired with the BeFree filter and there are other manufacturers also moving to the wider 42mm neck thread. I tend to use one of the green-brown HydraPak Seeker bladders (a colour described by HydraPak as ‘mammoth’), either of one litre or two litre sizes. The murky colour of the water container easily signifying that this is the ‘dirty water’ requiring treatment before drinking.
Another good pairing option for the BeFree filter is the collapsible 1 litre HydraPak Flux bottle. This has a neck loop/bail handle and slightly thicker walls than the HydraPak bladders to enable it to stand unaided and weighs 65g with no cap, 79g with supplied spill-proof twist Flux cap, or 100g with a dry BeFree filter attached. The BeFree will also fit the wider neck option of the Cnoc Vecto but I had poor experience with standard Cnoc offerings leaking so never purchased the 42mm neck option.
Three Points of the Compass has always found this squeeze style of filter user friendly as it is (almost) idiot proof, has little to go wrong (with care) and few parts (less to lose). The flip top cap has never broken on me but I have found it either stiff to open or close on occasion, and it sometimes refuses to click closed entirely. Just about any ‘standard’ drinks bottle cap can be used instead of the supplied drink nozzle if necessary. In May 2021 Katadyn introduced a BeFree gravity feed set-up that has a different cap attached to the same filter, however Three Points of the Compass does not utilise that filtration system so has no experience of this cap. But, the option is there for those that do.
Drying out the filter after a trip is something to be carried out with care otherwise a couple of things can happen. Calcium and other mineral deposits can harden with deleterious effects on future performance, or mould can grow. There are necessary steps to be followed- add a chemical water treatment/purification tablet to 0.5lt of clean water, or four drops of unperfumed bleach, and squeeze it through the filter. Allow to thoroughly airdry before storage. Mine sits on the windowsill in the sun, or on top of a radiator, for a few days. If calcium deposits are suspected, standing the filter in a glass of water to which a little white vinegar has been added will dissolve this overnight, followed by flushing with clean water. Before next use I stand my filter submerged in a glass of water for a day or two before running a couple of litres of clean water through it. This softens any hardened precipitate on the tiny hollow tube filter membrane. Standard ‘in the field’ cleaning is achieved by shaking or swishing the filter body in a body of water, alternatively filling the water bottle with clean water, screwing the filter on and shaking it to dislodge debris before emptying the water out. The filter should not be held horizontally under running water to clean as this can damage the membrane housing, enabling unfiltered water to find its way through as a result. I clean my filter pretty regularly. If I am staying a night in a hostel or bunkhouse I take advantage of access to a sink and clean water to swish my filter around in. By keeping a filter attached to a bladder, albeit often part-filled with ‘dirty’ water, this also keeps the filter membrane wet and movement while walking discourages settling or building up of precipitates.
The continued integrity of a BeFree filter can be checked via a simple test- ensure the filter membrane is wet by running clean water through it, then attempt to blow air through the drink nozzle into the softflask. If air passes through, the filter is damaged, if this isn’t possible, then the filter is OK. This test does not work if the filter is dry as air passes through fairly easily.
The BeFree filter has a limited life of course and will require replacing. I have never reached the supposed 1000 litre limit on any single filter but have lost a filter when I dropped my entire hydration kit into a flowing river. I have also had to replace a screw-on filter cartridge when I left it in my shelter vestibule overnight and the temperature dipped too far. Replacement filters are sold as a separate unit. After a few years of the standard blue plastic filter being on sale, a ‘tactical’ version joined it on sale as an option. This filter is identical apart from having a black plastic body instead of blue. Named the ‘EZ-Clean Membrane Filter Cartridge – Black Edition‘, this could originally be purchased paired with one of HydraPaks brown coloured soft flasks but is now also available as a stand-alone cartridge. While I was not particularly concerned with owning a black bodied filter, the first pairing did mean that I was able to purchase a spare cartridge as well as now having the dark coloured one-litre HydraPak option should I want to swap out with the larger two-litre bladder. With regards to that 1000 litre life expectancy, some other filters advertise a life expectancy far in excess of the BeFree filter however that is dependent on backflushing under pressure, something very few users actually effectively achieve. Despite some users advocating it, Katadyn advise that the BeFree should not be backflushed.
There is an additional filter pairing that snuck past many as it was primarily aimed at runners. Salomon have been producing clothing and equipment for outdoor activities since 1947 and from 2020 they increased the neck size on many of their runners bottles to 42mm. In Spring 2020 they announced the release of their Salomon Soft Flask XA Filter. Currently priced at £40 (2022), this has a 490ml capacity and utilises a filter cartridge with obvious similarities to the BeFree
While Three Points of the Compass has been content with mostly using the BeFree filters for the past few years when on trail, I have used other filters and water treatment methods occasionally and continue to keep an eye on the market. Viruses in water are particularly nasty. They include hepatitis A and E, adenovirus, rotavirus, norovirus etc. I see Katadyn now also produce a ‘BeFree Hero Fast Flow‘ filter that is capable of removing viruses, in addition to bacteria and cysts, from water. This is unlike the standard BeFree filter cartridges that cannot remove viruses. Advertised by Katadyn as only available to Governmental Customers at present, this product is advertised as capable of filtering up to 500lt at a flow rate of up to 1lt/min, as opposed to the 2lt/min that the standard BeFree filter is capable of when working optimally.
Katadyn informed me that they have no intention of putting the Hero Fast Flow filters on general sale to the public but are developing new retail products that will be capable of virus removal. Until then, if I have concerns about viruses in water, then water purification is a two-step process.
With reference to the efficacy of a two-part process, while Cryptosporidium is easily removed by a micro-filter, it takes up to four hours for Chlorine Dioxide to kill this and some other protozoa. So particularly dodgy water is first passed through my BeFree micro-filter to remove floaters, turbidity and the very great majority of protozoa and bacteria, followed by chemical treatment to kill off viruses. My favoured Chlorine Dioxide tabs are sourced from Lifesystems and chemical treatment is completed in my ‘clean’ drinking water bottle. It is worth noting that for the most effective use of chemical treatment, water being treated should be kept out of sunlight as this affects performance. An additional mention here on Steripens and their like. Three Points of the Compass doesn’t use this type of water treatment and they are not recommended for use with the soft sided TPU bottles and bladders produced by HydraPak and other manufacturers. SteriPens use ultraviolet to treat water and UV can damage a TPU film, potentially causing leaks.
Almost all micro filters use the same technology, in different set ups, with minute differences in the hollow fibre membranes incorporated into each brand of filter. Some will have slightly narrower hollow fibre membranes, others slightly larger. Some will have thinner walls in the hollow fibres, others will be thicker. Some manufacturers simply cram more hollow fibres into their filter body than others, thereby improving flow rate. I mentioned earlier that I had inadvertently compromised (read- destroyed) a filter by allowing it to freeze. This is a problem common to all micro-filters. If allowed to freeze while wet, the expanding ice within the hollow fibres can split them. You may not even be aware that safety has been compromised as there is no outward sign of damage. An integrity test can be completed (by blowing through the nozzle) but the safest method is to either not use the micro-filter system in freezing conditions, or keep the filter away from the cold outside the pack during the day, and next to the body, or inside a sleeping bag at night. A ziplock bag in which to keep the filter while it sits in the footbox of my quilt at night is essential. I then also carry a spare 42mm cap for the bladder so that doesn’t have to be kept inside as well.
None of this is to say that a BeFree filter is the perfect solution for producing clean, safe water. It is all about risk reduction and what suits the individual. Other methods- boiling, chemical treatment etc. can occasionally be more effective. However my BeFree filter is pretty much idiot proof and reduces most of the risk for this UK based backpacker. It takes little effort to use, has a quick flow rate, the filter reduces pathogens to a level that is acceptable to me, and also removes sediment. It is also easily cleaned as required. There are exceptions where I will not rely on this filter. It is seldom that I am simply relying on any filter in lowland agricultural England where I have too many concerns about industrial and farm chemical runoff into water sources. This is particularly the case in South-East England. There is little that any filter can achieve where heavy metals, pesticides and herbicides are present in water.
I still carry chemical water treatment in my dittybag and as mentioned will use this with my BeFree filter in a minority of occasions. The purpose of a water filter is to stop me getting ill, or at least reduce the chance to an acceptable level (for me). That’s it, nothing more, nothing less. So perhaps it is unsurprising that anything that dramatically lessens the risk of me getting sick is one of my favourite pieces of gear.
This blog is part of a short series looking at favourite pieces of backpacking gear. Others in the series have been:
Three Points of the Compass 
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