Tag: Water

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Katadyn Pocket filter capacity: The verdict is in

I purchased a Katadyn Pocket filter in 2012 for a variety of reasons, the principal amongst which was to have drinking water at my cottage during the off season (winter) when the water system is turned off to protect it from freezing. Issues such as not wanting to depend on neighbours and even just whether or not the neighbours were there, the relative convenience of having as much water as I was willing to filter when I wanted regardless of the hour, and not having to transport very large quantities of water from the city, circled through my head.

Like so many other people, I repeated in my blog the 50,000 litre nominal capacity of the filter cartridge as a deciding factor in the purchase of this particular filter. Despite having accepted the value as a ballpark figure to mean “you’ll get lots and lots and lots of water, a few orders of magnitude more than other filters”, I also recognized the ballpark nature of the figure, and that actual capacity would vary (possibly considerably) according to real world conditions such as varying water quality and just how vigorously one might clean the filter cartridge. Unfortunately, I have been disappointed with just how variable this figure has actually proven to be in my case.

In 2016, I began wondering about the real life capacity of the filter cartridge, given a noticeable change in pumping experience filtering water from my artesian well instead of melted snow from my front yard at the cottage. The obvious visual wear of the filter gave me a reference point, and, having kept notes, I revealed that since purchase and up to that point, I’d only filtered roughly 1,500 litres. I had estimated that I might attain a very rough total capacity of 3,000 litres.

In 2017, I had passed a benchmark: The plastic gauge that had come with the unit had passed over the filter, at about 1,650 litres, and by the time I’d written the post, I’d reached 1,750 litres. This represented 3.5% of the nominal 50,000 litre capacity. I mused over the lack of any reported real life capacities that I could find on the internet, going through some hypothetical arithmetic I was able to develop from one source.

I knew that I wouldn’t get anywhere near the oft-touted 50,000 litres. In anticipation of needing a replacement filter cartridge, I went to a store selling them, hesitantly because the replacement part has a fairly expensive price. I purchased a replacement, and was pleasantly surprised to get a 73.2% discount on the price at the counter (for reasons unknown). I surmised that a part of the discount was since the unit was in a box that had obviously been opened and resealed, although why it was so significant still eludes me. The only thing in my favour were the local consumer protection regulations requiring that in the case of a difference between the advertised price and the price at the counter, the consumer gets either up to a $10 discount from the advertised price if lower than the value at the register, or the value of the register price if lower than the correct price.

Since January, 2017, when the gauge passed over the filter unit, I have been bringing somewhat more water up to the cottage, up to five gallons at a time instead of just a single gallon, in order to somewhat extend the life of the filter cartridge. I have been continuing to use the original filter unit, wanting to take full advantage of its lifespan.

During my most recent weekend to the cottage in April, 2019, I began filtering water as usual. The filter had been cleaned and bleached prior to use. However, the filter quickly clogged, and suddenly, the plunger went down quickly; the unit’s internal pressure had been sufficient to collapse that which remained of the filter.  

The collapsed filter, note that the element has been worn and significantly ablated

It should be noted that the filter failure was due to the fact that over time and hundreds of filter cleanings, it had been physically worn away, and therefore the failure was due to it being thin (about 1mm to 2mm thick) and not because I’m inventing a frivolous claim of manufacturing defect.

I also have a definitive capacity of the cartridge I received with the original  purchase, under the various conditions of water quality I filter and maintenance: approximately 2197.5 litres (let’s round that up to 2,200 litres), or 4.4% of the stated 50,000 litre capacity. It was used up over seven off seasons at the cottage, providing a significant amount of the drinking quality water needed for cooking, cleaning, and drinking.

It seems that I didn’t get anywhere near the nominal capacity. Sigh.

Now it’s time to see how much capacity I get out of the second filter.

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Katadyn Pocket Water Filter Capacity — Update II

In 2016, I wrote about my estimate of my Katadyn Pocket Filter’s real life capacity.

I had reached an estimated 1,500 litres of filtered water over four winter seasons of using the filter at the cottage during the off-season when our water system is turned off. I had further guessed — hoped, really — that I might get as much as another 1,500 litres, spread over two to four more seasons, and as such it might take as long as until the year 2020 to know when the filter cartridge would need to be replaced.

I was overly hopeful. In January of 2017, I was up at the cottage for a week, doing a lot of cooking and needing a good amount of filtered water.  I tested the filter unit against the gauge supplied with the filter, and since the gauge passed over the filter unit, “it was time” to change it.

The winning total (as of January, 2017):  1650 litres. Or, about 3.3% of the oft-touted capacity of 50,000 litres.

As of September, 2017, I have not replaced the filter yet, and am at approximately 1750 litres, or about 3.5%.

This makes me wonder, yet again, what Katadyn knows about the “in the wild” capacity of its filters.  As in, how come I have only gotten 3.5% of the rated capacity of the filter before it has worn out.

And it makes me wonder why, in my perhaps modest efforts to find out how much water people actually filter with their units, just about everyone (including myself, admittedly, shortly after I bought the unit) talks about 50,000 litres, but few talk about “well I only filtered this much before I had to replace it”, or the like.

There are reviews I found on the mec.ca website there from people whose posts are meant to imply that they’ve gotten a lot of use out of their filter.  I saw one that said that over 25 years, the person was on their third replacement, and claimed to have filtered over 250,000 litres! (or over 62,500 litres per filter!)

A comment I came across said “I bought mine in 1988 and I have yet to change the filter”.  I can imagine that over 29 years one might have used it quite a number of times; but what, every weekend for groups varying from two to five people? Once or twice a year when they take their children hiking one afternoon around the cottage or campsite that they rented for a few days during the summer holidays, and the rest of the time they’re on a water system? Or “I’m an avid hiker who goes out hiking every weekend I can, and I bring my Scout Troop hiking all the time and they are constantly asking me to filter water for them”?

Yes, I have seen some reviews that are “a bit more detailed” than that, such as “well after 15 years I replaced it, having filtered thousands of litres of water” … which still begs the question: Thousands of litres of water … that sounds vaguely less than 50,000; 7,000 litres is “thousands of litres”, as are 4,500 litres, and 25,000 litres. So did you keep a log of roughly how much you filtered? Trip diaries such that you could guestimate or have a basis on which to assume that each trip you used it, you typically filtered a given amount a day and you were gone a given number of days, and at least have a ballpark idea of how much water was filtered?

And here’s one that I found mildly useful:  “I used it travelling for 18 months through India, and used it instead of buying bottled water all the time” … but that doesn’t really tell me how much water they filtered.  But, it allows for some hypothetical arithmetic.  Let’s say there were two people producing let’s say three litres per day per person for 18 months — 548 days, give or take — that’s 3,288 litres, or almost 6.6% of the rated capacity of 50,000 litres.  At four litres per person per day, that’s 4,384 litres, or almost 8.8%.  At five litres per person per day, that’s 5,480 litres, or almost 11.0%.  Now that’s a lot of drinking water, both per person, and just a lot of water to filter in a given day while travelling.  After that, I have to ask what they were using the water for!  Were they filtering enough water to wash their clothing and showering or bathing?  If so, given how much time it takes in reality to filter a few hundred litres a day with the unit, were they spending *all* of their time filtering water and not actually taking advantage of their trip in India?!?  And, of course, it should be noted that they *didn’t* mention that they bought the unit expressly for this trip, or never used it again before or after.

I am obviously getting worked up: Were I to have filtered 25,000 litres (50% capacity) or more, over a decade or two, I might not be as upset, and would likely chalk it up to the expected variation in the field due to “real world circumstances”. However, losing more than 96% of the rated capacity is frustrating to the point of unacceptable, to say the least.

The only consolation?

In January, 2017, after having passed the plastic gauge over the filter unit and having learned that it was at the end of its designed lifespan, I went to a Mountain Equipment Coop (MEC) to buy a new filter unit, not really sure whether I wanted to go through with the expensive purchase; the replacement filter units cost $235, compared to $435 for a new complete unit.

The last unit on the rack — which is the unit I therefore bought — looked like a returned unit. (Later when I got home, I was able to open it and learn that everything was there: A new filter unit, a new spigot hose, new o-rings, a new scrubby pad or two, a new bag for the spigot hose, a new tube of lubricant, and whatever else was supposed to be there.)

The list price: $235.00

The price that rang up at the till: $63.00

Discount: 73.2%

I did a double take, and without thinking I said, “That isn’t the correct price.” I of course should have kept my mouth shut, but no matter:  Québec’s consumer protection laws were on my side. Were the price at the register to be higher than the advertised price, the customer would pay the advertised price, less a $10 indemnity (with a few exceptions as well as a few other pricing rules applying as per the case); if the price at the register were to be lower than the advertised price, then the customer would pay the lower price, regardless of the difference between the two prices.

Nonetheless, we went through the motions of verifying the price on the MEC website, and indeed confirmed that the list price was $235.  However, either the clerks were savvy and well trained, knowing the law in this case, or they were naïvely trusting of the price scanner / computer / register, and insisted that the $63 price that rang up on the machine was the price to be paid.

You can be sure that the next day, I made a point of going back to the same MEC to see if they’d restocked the shelf with that item, in order to hopefully take advantage of another massive discount. Sadly, they had not. And, I expect that the store knew that the item I bought was the last unit in the store, and that (I presume that) it was a returned and restocked item, hence (presumably) the discounted price. Perhaps this doesn’t explain just how deep the discount was, but it nonetheless explains some of it. A few months later, I was at another location of the MEC and I looked at the section with water filters; they had replacement cartridges, in factory sealed boxes of course, and the price at the rack was $235, as expected. I did not dare ask for a price check. 🙂

So the experience was not a complete loss, to the point of it almost having a mildly pleasant dénouement, but the deep discount on the replacement unit still does not make up for the remaining 23.5%-ish of capacity I had expected but did not receive, and continue to not expect to receive, out of the original filter. Which, incidentally, as of September 2017, nine months later, has not yet been replaced; like one of the pub patrons in the following joke, I want to squeeze as much capacity as I can out of the filter before I finally replace it.

The promised joke:

Three people are in a pub, each ordering a drink of their preference. Unfortunately, each drink comes with a fly in the glass.

One returns the drink and requests a replacement, without a fly of course.

Another removes the fly from his drink, and proceeds to drink it.

The third grabs the fly from the drink and calls out “Spit out every last drop, you little scoundrel!”

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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

Update, 2019:  Here is the verdict of how much water I filtered, in 2019, after about seven seasons

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Katadyn Pocket Water Filter

During the summer of 2012, I bought a Katadyn Pocket water filter. It took a bit of research, but in short order the decision to buy this model over just about any other was clear: Most water filters seemed to have a capacity of a few hundred gallons or maybe up to 1,500 gallons; the Katadyn Pocket filter has a capacity of up to 13,000 gallons, or 50,000 litres. Given the price difference — anywhere from $75 to $250 for most of the rest, and $300 to $350 for the Katadyn Pocket, there was little to decide.

The unit has a 0.2 micron ceramic filter with silver impregnated in it in order to act as a bacteriostatic agent, although you have to be careful about that (see below).

The only thing that bugs me a very little bit about it is that it’s a filter only (albeit very good), not a purifier. Unfortunately, the purifiers don’t have the capacity that this filter has. This works out to the fact that the unit can effectively remove all bacteria and cysts — and of course cloudiness — in water, but theoretically it can’t remove viruses due to their being far smaller than the pore size (unless they electrostatically attach themselves to a particle which can be filtered out by the unit). It also means that it doesn’t remove any other contaminants smaller than 0.2 microns, including the usual nasties one might think of such as dissolved heavy metals, pesticides and other such nasty contaminants, and the more benign but nonetheless undesirable tastes, odours and colours that aren’t due to cloudiness.

There are two ways of dealing with these issues:

1) Choose a clear water source — that you might be tempted to drink without treating it at all (your natural “yuck” factor will help you out with this) — and this will reduce the likelihood that these are problems to begin with. By itself, most people — including myself, a trained water techie — can’t just look at clear water and tell whether it’s contaminated with the poop of 30 deer 100 feet upstream, or the dumpings from some illegal leather tanning shop 200 feet upstream. But, generally, you can tell the difference between clear, running water in the middle of the woods far away from just about anything and that doesn’t have any smells to it, and stagnant, cloudy and smelly water in the ditch surrounding a garage.

2) Bring around a small bottle filled with bleach and an eye dropper (*). I find that depending on the water source and the strength of the bleach (typically 4% to 6% sodium hypochlorite), 1 to 3 drops per imperial gallon (4.5 litres) has worked well on the filtered water. Melted snow from my cottage could do with 1/2 drop per imperial gallon, given that the bleach taste still often comes through quite distinctly on such (presumably) relatively pure water. As a reference, the USEPA (here’s my archive) recommends to use two drops per quart when using bleach to disinfect untreated water, or about 8 drops per US gallon (3.78 litres), or about 9 drops per imperial gallon (4.5 litres).

(*) This won’t deal with a bunch of dissolved metals, and can’t completely deal with tough contaminants, so choose your water source carefully!

Now, putting aside that I’m a water techie, why would I, who stopped being involved in Scouting and most forms of camping and hiking in 1999, need such a device?

The family cottage doesn’t have running water in the winter, and I usually spend a week over Christmas and typically a weekend a month at the cottage over winter, when the water is off. I’ve been starting to get tired of carrying up big jugs filled with water. I’ve been getting tired of running out of water or at least having to be careful about how I use water. And, particularly, I’ve been getting tired of depending on a few neighbours for their goodwill. The operative notion here is “depending”; a lack of goodwill is not the issue, although the variability of whether or not two of the immediate neighbours would be around all the time is a concern alongside the inconvenience of having to go out to get clean drinking water in the middle of washing dishes.

One of the first things I had to figure out the hard way is the importance of keeping the unit clean (go figure, a water techie needing to be reminded of the importance of keeping drinking water treatment equipment clean): Over almost two weeks in the summer, I’d used it three times, and ended up with a good case of diarrhea which took a couple of weeks to clear up. So note to myself, and those considering buying any camping water filter: Keep the unit and the outlet hose in particular clean — it can get contaminated easily — and when you’re going to leave it sitting around for more than a day or two or pack it away for a while, run a bleach solution through it first and dry it out.

So, does the filter work? And do I get the runs any more?

Of course, and of course not.

This year over Christmas, I found it quite useful, although I did bring up a good supply of water anyway to begin with, given that I was coming up for a week and the long-awaited testing grounds had finally arrived. I needed some kind of starting point, in case I found out that “making” water was a lot more work than I’d bargained for, especially given all the freezer cooking (and therefore dish washing) I do over that period.

I also confirmed what I had begun observing for years while melting snow for things that didn’t require drinking-quality water: You’d be surprised how much dirt and debris comes through when melting “pristine” snow in the middle of cottage country, far away from the city. It’s but a little more appetizing for drinking, cooking or rinsing the dishes than dishwater — so of course I don’t bother filtering the melted snow for my “put the dirty dishes in hot soapy dishwater” part, but of course I use filtered water for rinsing the dishes.

Regarding the amount of bleach to use, I have found that the filtered water from melting snow needs about a drop per imperial gallon, while the filtered lake water can handle about two drops per imperial gallon, before a distinct bleach taste comes through. This is a little testing based on working with the filtered water and after having first consulted some tables on how many drops of bleach per litre to use for treating water (here’s my archive) (instead of just calculating it myself). As a reference, the USEPA (here’s my archive) recommends to use two drops per quart when using bleach to disinfect untreated water, or about 8 drops per US gallon (3.78 litres), or about 9 drops per imperial gallon (4.5 litres).

Regarding the “one litre per minute” claim, it mostly works out to that, sort of, I guess — which means, not really. In practice, though, I suspect that that’s based on filling up one litre or one quart water bottles commonly used, especially in camping and hiking circles. For larger amounts of water, it takes longer. The best test I’ve had — since filtering water while being distracted by the TV at the cottage isn’t much of a test — was when I recently filtered about 23 litres of melted snow undistracted for a future batch of beer, and it took me about 40 to 45 minutes. This admittedly but importantly included a stop about halfway through to open up the filter and clean the ceramic filter, which had become sufficiently dirty from the dirt in the “clean” snow that I’d melted, making filtering the water difficult. A comparison between the 100 metre race and the 3,000 metre race in the Olympics would be apt: You sprint in the former race, but you pace yourself at a somewhat slower running speed in the latter in order not to get too tired right away and be able to make it to the end of the race.

Anyway, I like the filter, and it should get several years’ worth of use before I have to start thinking about buying a replacement filter cartridge.

Update 08 June 2016: Katadyn water filter capacity — update