I bought this filter in the late 1990’s to be used mostly for backpacking.
A close friend of mine had (and still has) the precursor to this from the early 90’s called the WaterWorks Total Filtration System. It worked well, he liked it and still uses it occasionally. My MiniWorks was the new, improved, smaller version just on the market and targeted to “serious outdoor enthusiasts.” I fit that bill at the time and decided to splurge on this piece of high-end gear in hope that it would make my adventures safer and easier for years to come. It has done all that I asked or hoped for over that time. This important piece of gear has served flawlessly over a long reign of quality service on literally hundreds of adventures over those decades. I bought a 6 liter MSR Dromedary bag at the same time and they worked well together. Sadly and just recently I made a mistake and the filter was neglected by me and had a crucial part break. I left it out at night still wet after being used where it was subjected to below freezing temperatures and the original ceramic filter element cracked. I had known about that possibility but apparently forgot at an inopportune time when temps dropped below freezing (I recorded a low of 26F/-3.3C on my little LaCrosse Weather Station.)
That crack on the left turns right back around and heads all the way back up to the light blue plastic area. The little piece that created is noticeably loose within the surrounding ceramic area.
Luckily that cold night was our last there and I didn’t need to use the filter again but if I had I would also use Aquatabs after filtering.
When I first looked into replacing the filter element what was shown to me looked almost nothing like my existing one. Not wanting to buy a wrong part and hoping to not need to replace the entire filter system I did some online sleuthing. Knowing how old the original filter element was and finding pictures online of the different versions of that filter over the years I deduced I had the original Marathon 205 version. It went out of production in 2002 and was replaced with the Marathon EX Ceramic Element in 2003. This second version was discontinued in 2008 and replaced with the current MiniWorks/WaterWorks Ceramic Element. I have read online that this newest version is supposedly backwards compatible with my original MiniWorks pump and “provides 25% faster filter rates compared to pre-2003 models”. The newest version of the MiniWorks filter system also has something called “AirSpring Accumulator technology, which allows it to pump water 45 percent faster” and claims 1 liter per minute of pumping. That is definitely a better rate than what I was getting with the old filter element although that slower throughput could easily be blamed on some “less-than-optimal” maintenance on my part over the years. I have never done a “scientific” study to see how many pumps over a specified amount of time gets me what amount of water in the dromedary bag but anecdotally I seems like it takes about 10-12 minutes of continuous pumping to get maybe 5 liters into the bag. Also, unintuitively, pumping faster does not equal faster filtering. The filter’s manual suggests “about 70 to 80 strokes/minute for optimal performance. Pumping faster than that creates cavitation in the water flow, which you can easily hear, and noticeably lessens water throughput. I’ve settled on around one pump per second which is easy to physically maintain and keep steady with a mental “one thousand one, one thousand two,…” cadence.
Sadly, my old pump does not have that “AirSpring” feature so any improvements I see will be solely from the filter element itself. I expect to not be overwhelmed by any newer, faster filtering with this new filter element but I’ll happily take whatever performance improvements that I can get. It would make me happy to not have to purchase an entire new system or take the opportunity to upgrade and instead simply replace the broken ceramic element and get an improved version. So I gave that less expensive, more efficient option a try first.
I found and ordered the new filter element directly from MSR which happened to be substantially cheaper than the same item at Amazon (so I won’t post a link to that item there).
The new filter elements are basically the same size but look quite different.
The filtered water comes out from that nipple in the top center.
Besides the Filter Housing o-ring that sits along the threads at the top of the filter housing the old element needed two other o-rings for correct operation. Those two are silicon rings of different sizes (the Lower End Cap and Upper End Cap o-rings) for the top and the bottom of the filter element itself.
The new version makes due with just one, the Lower End Cap o-ring as well as that Filter Housing o-ring. The new filter element came with a new Lower End Cap o-ring, a new ceramic gauge and another small piece of green scrubbing pad. My old bottom o-ring was in excellent shape so I will keep it for a spare just in case.
The new filter element fits in place of the old perfectly in the housing. That black plastic part at the top of the new filter leaves no room for the old o-ring.
When I performed the initial purge of the new filter to remove residual carbon dust before its first “real” use I had a slight worry that only having the one Filter Housing o-ring might allow leakage under pressure but I saw nothing of the sort. After that initial rinse the filter element is now sitting outside in the sun. It will stay there for several days (MSR recommends 3-5 days) to ensure it is as dry as possible before I reassemble it and store it back in my camping gear until my next adventure. I’ll have to wait a few months until I am free to head back out into the wilderness but a small weight has been lifted now that I know I still have an effective way to filter found water if need be.
I am annoyed that my negligence broke this tool but thrilled I was able to replace just the broken $50 part and not need to spend $120 on a complete, new system. Kudos to MSR for still producing a compatible part while also making improvements along the way. I love my hybrid system now with a 1st generation housing and pump system and a 3rd gen filter element.
If perhaps this little post peaked your interest in the history and development of this filter, MSR has an pretty thorough telling on their website.
PS: As an aside probably only of interest to me, this published post puts this whole website now at 299,276 words for an average of 1,360 words per post. I expect we will break 300,000 words after my next post which means… well absolutely nothing but seems like a good collection so far.
Thanks for reading.
Have fun and stay safe out there.