Katadyn water filter capacity — update

This is an update to my post from 2013 on the Katadyn Pocket Water Filter.

In 2012, I bought a Katadyn Pocket water filter principally for use at the cottage during the off-season when our water system is turned off, plus a small handful of personal interest reasons like being a trained water techie, having been involved in Scouting, camping and hiking a long time ago (but no longer), having been involved in geocaching which can involve some hiking in the woods, filtering water from snow or ice for my homebrewing (mostly just to be able to have a story to tell about the “specialness” of the water), and generally to use for my amusement while hiking around at the cottage during my holidays and other times.

About two thirds of the way down the above post, I asked “So, does the filter work? And do I get the runs any more?” to which I answered with an obvious tone, “Of course, and of course not.” Those answers are as true today as they were back in 2013.

I use the filter principally up at the cottage during the off-season, about mid-October to mid-May (during the winter, when the water at the cottage is turned off due to freezing weather), for my water needs for drinking, cooking, hand washing, and dish washing (normally, just the rinsing part at the end.) Obviously, as long as the water isn’t grungy, a lot of water doesn’t need to be filtered to begin with, like for soaking dishes before cleaning them, or as long as it’s fairly clear, for washing my hair and taking a sponge bath.

Every year, I keep a register of the amount of water I filter, as a function of the five litre plastic jug to receive the filtered water, which I always fill up to the brim. I’ve checked the 2014-2015 and 2015-2016 registers (I can’t seem to locate the previous two), and I respectively had filled the container 67 and 72 times. That adds up to roughly 695 litres of water. There is going to be some variance in this number, since I when I fill up my container for brewing water, I skip using my 5 litre container and fill the brewing water container directly.

Assuming that during the previous two winters (2012-2013 and 2013-2014), I’d used it similarly, let’s say that I’ve filtered about 1,400 litres. Add to that the very occasional use during the intervening summers, let’s say a good 100 litres, and I’m up to about 1,500 litres.

Here’s the clincher, though: The ceramic filter is visibly wearing down after four seasons of use, and I’m certain I won’t get 50,000 litres out of it.

Normally when I use the filter to filter melted snow or lake water, I have to clean the filter typically after about 12 or 13 litres, because it’s becoming too difficult to filter water at that point due to the ceramic filter clogging up. On general principle, barring the exact number of litres, this is normal and has always been to be expected.

However, recently I noticed something I find curious: During my most recent usage, I was filtering water from the artesian well, which is a good 60 feet deep. I was filtering this water since while the water system had been turned on, I hadn’t yet bleached the well after the winter to clean out the well as well as the house’s pipes. The curious part: I was able to get to 20 litres and beyond without any increase in difficulty in operating the filter, and were I not to have been too curious and opened up the filter for a preventative cleaning, I would have been able to filter an ample amount more.

The well, being a good 60 feet deep, is therefore supplying water that has been very nicely filtered by typically 60 vertical feet of gravel and sand. Further, since I’m assuming that the aquifer is at least somewhat dynamic, I assume that one day the water I’ve drawn from the well could have been rain water or lake water from a few days previous that trickled through the 60 feet of gravel and sand on my property, while another day the water may be runoff having traveled through I don’t know how many hundreds or thousands of lateral feet of sand and gravel from the hills behind my cottage. As such, the water is presumably — and I assure you, actually is — sparkling clear.

This is as compared to when I filter lake water or melted snow, the latter of which, may I remind you, is not quite so pristine as you may think, even when excluding the yellow variety; it is relatively chock full of dust particles that fell with the snow or became nuclei as part of the condensing and / or crystallization process. At this point I assume that at least some of the dust particles may be coming from the various chimneys at the cottages surrounding mine, including the chimney from my own cottage.

Which leads to the notion of this post regarding the filter’s capacity.

The filter is rated as having a capacity of “up to 50,000 litres”. When I bought the unit, I did recognize this to be codespeak for “Depending on the source water quality, the capacity may and will be reduced in real life.” Unfortunately, as it seems in my experience so far, possibly by a very significant margin.

However, I am wondering exactly when I’ll be needing to replace the filter. Yes, I have the little gauge to measure the filter thickness, and I use it occasionally. The question *is*not* “How will I know when to change the filter?” The question is “*When* will the ‘when’ be.” Let me explain.

I’d guess I’ve worn down at least half of the working thickness of the filter in the past four years of use over roughly 1,500 litres, especially if my vague memories of where the gauge the unit comes with was at when the filter was new are correct as compared to where it is now, and just visually guestimating the wear against where it obviously used to be when it was new.

And here’s the conspiracy theory:

I bet that the 50,000 litre estimate that they give is based on using either laboratory grade distilled water, or perhaps treated tap water intended to be potable.

I know that everyone’s source water will be different, and generally using it while traveling to areas where the tap water is clear but not quite potable is as legitimate a use for the water filter as filtering swamp water while out hiking.

(As a side opinion: Regarding dubious water systems while traveling, depending on where you go, unfortunately outside of the westernized world — and even within it in some cases — the tap water may not be quite potable at least from a microbiological point of view as one might expect or hope it to be. The water system can be dubious at best due to antiquated pipes, or the production plant is old and breaking down, or the employees are severely underpaid, or there aren’t enough of them to do the work well. And that’s just the areas which have a distribution system, and that isn’t delivering water that’s smelly or cloudy or outright foul.)

But I’m wondering just how long my filter unit will actually last. For the moment, I’m betting on another two to four cottage seasons, or “up to” another 1500 litres, the way I’m using it. That’s still far beyond other filters where the unit has a nominal capacity of a few hundred litres, and the filter unit itself is disposable and needs to be replaced the way a razor blade in a razor has to be, or ink cartridges in a “wow this printer isn’t expensive at all!”. Ultimately *a* *part* of what makes the other filters, razors with disposable blades, or ink jet printers so deceptively inexpensive is that the manufacturers make their money in selling you spare parts and refills.

I know that the kind of water I filter and of course its quality are far beyond Katadyn’s control. I know that if I’m filtering snow where a good amount of the particles to remove are composed of fine mineral dusts, there will be a sandpaper effect when I’m cleaning the filter, versus filtering stream water where the solids to be removed are more likely to be decaying organic matter in the form of fish poop and dead leaves, which will be easier to clean off the filter when the time comes. I know that the filter is designed such that when it is being cleaned, the process is meant to be ablative. But I’m wondering how much of my perceptions are, well, perceptions and not real life, how much of my use represents an edge case, how much my of cleaning is a bit too vigorous, and so on.

And I wonder just how much Katadyn knows that the 50,000 litre mark is about as close to an imaginary number as it can get. (Or conversely just how delusional I am. 🙂 ) I’d love to see their internal graphs on the real life capacity of their filters. I’d love to see the range that their customers get out of their filters.

So Katadyn: Here’s my estimate, for my filter — about 3,000 litres, given the kinds of water sources I’m using (cottage country snow, some lake water, and a small sundry other sources like streams when I’m hiking, etc..) At the rate I’m going, I expect that it may take as long as until 2020 to find out, though. 🙂

Any and all Katadyn Pocket Filter users are invited to leave your estimate — I hope at least somewhat evidence based — here, or send me an email malak at the site malak dot ca