Welcome to the future of outdoor equipment: fanciful, superlight, ultra-compact, convenient, and only good for the first few uses.  This is MSR’s new water filter, which came with a considerable amount of hype.  It is advertised as being able to pump 3 liters per minute, weigh only 8 ounces, and be the end-all of water filters.

These things are true.  I had been trying to track down a Hyperflow since the February before I started the trail, to no luck.  It was just being released in March, and slowly at that.  It was in high demand at first, and I couldn’t find one in stock anywhere.  Everything I had read about this filter was good, and even better it was half the weight of my current filter.  It seemed MSR had finally outdone itself.  It filters water through a hollow fiber technology, which is basically like a bundle of tiny straws tightly bound together.  Supposedly it could fill a nalgene bottle in about 10 strokes of the pump, or 20 seconds.  I saw a video on some site that showed this to be the case, and I could not wait to get rid of my MSR miniworks, which weighed about a pound and pumped roughly 1 liter per minute.  The Hyperflow seemed almost too good to be true.

This turned out to be the case.  After finally getting ahold of one in May, in Troutdale, Virginia, I was eager to swap out the miniworks.  I hooked up the hose to a bottle, and immediately discovered that this thing didn’t just pump water quickly, but it actually could squirt water 20 feet or so.  It was like one of those poolside water canons, where you suck the water in and then blast your friend with a healthy stream of chlorine water.  I was so excited about it, that I immediately mailed the miniworks home and hit the trail.

My water filtering bliss lasted for about the first two days.  After the filter clogged for the first time, which was roughly 8 liters, it was never the same again.  MSR says you can clean the filter by reversing the nozzles and backflushing clean water through.  What they don’t tell you, (or didn’t know themselves due to rushing this product out the door)is that backflushing only restores some of the funtionality of the filter.  Having carried this thing for 1700 miles on the AT and struggling against it all the way, I can also say that it is a system of diminishing returns.  In other words, the first cleaning will restore it to not-quite original performance.  The next time it needs flushing, it won’t return to how good it was the time before, and so on.  After a while it become very difficult to pump, requiring serious muscle power and considerable effort.  After a while I just stopped attempting to clean it, and just dealt with the hard pumping.

In addition to the flushing not actually working, there is another problem.  That is, it requires clean water to be flushed.  So once you’ve exerted sweat and muscle to painfully pump out one liter, you now need to pump that clean water back through, wasting your efforts.  MSR recommends you do this every 6 liters or so.  Not to mention, it is a real pain to take apart, reverse the nozzles, backflush, take apart again and replace the nozzles to the proper direction.   With the amount of water I go through for each day on the trail, that is about once a day, if not more.

There is one final design flaw that is not going to get fixed any time soon on this filter.  When backflushing, the pump pulls water through the clogged filter when you pull the pump out, which is actually relying on the vacuum created inside the chamber.  This vacuum is only so strong, and I found if the filter is too clogged, the vacuum is not actually strong enough to pull the clean water through.  In other words, if it gets too clogged, it cannot be cleaned at all.

I knew lots of people who rushed out and bought this filter, including myself.  I am the only person that I know of that did not send it home by the end of the trail.  I called MSR to complain, and they were all-too-eager to mail me a new $40 filter cartridge for free.  Everyone else I knew who was carrying one also got free cartridges by MSR.  One couple I knew had to have their cartridge replaced no less than 8 times, each one ruined after one or two days of use.  Another couple succeeded in getting theirs replaced with a Miniworks EX.  MSR is certainly aware of the problem, and it seems they are quietly admitting it by sending out so many free cartridges.  While this certainly helps, and I appreciate the customer service, it does not change the fact that the Hyperflow is essentially a 1 or 2 day disposable water filter.  While still usable when clogged if you are willing to work on your pumping muscles, this is not what the product was advertised for.  My advice?  Stay away!