Rating: 5 / 5
I've been backpacking and using filters/chemicals for 17 years. I also work at an outdoor retailer, so I see pretty much everything. Since I also get a good discount, I actually own a few filters. Personally, I own an MSR Miniworks EX, an MSR Hyperflow, and a Sawyer Squeeze Filter. My dad's had a Katadyn Hiker (actually an old Pur unit, but same thing) for 15 years or so, and I've used it hundreds of times. I've used MSR Miniworks in the field for years, and I've used pretty much everything else out there at least once. So far, the MSR Hyperflow is just incredible. Here's why:
1. SPEED! A full back and forth stroke takes about a second. It takes 20 to filter a liter.
2. Simplicity. No really. It all SEEMS so difficult with the back-flushing and all, but it's really not.
3. The pre-filter. This thing will suck water out of the sorriest water source on the planet.
Having said all that, this filter still scares me, and I'll carry backup for a few more test trips (Sawyer + Aquamira drops, about 5oz together). I just don't understand all the bad reviews. It worked flawlessly for me in some pretty crappy water. By the way, I bought this particular filter from a person on the internet who had issues with it. I got it cheap with a new filter cartridge.
I've only used it once so far, but it was used to filter about 20L over two days, and it seems most people have had problems by then if they had a bad pump. I experienced ZERO slowing or hard pumping. The source was a mountain spring at Oak Mountain SP in AL, and appeared to be fairly clear. However, it was a tiny trickle, and was only about 1cm deep, so even if it was nasty, it still would have appeared pretty clear. All the other water sources in the park were pretty cloudy and full of tannins, so it follows that my source was as well.
Had I used my Miniworks, I would have had to dig a hole and wait for it to clear just to be able to get the tip of the intake hose wet (same with a Katadyn Hiker). Had I used the Sawyer, I'd have spent an hour pouring 1oz of water at a time from my mug into the water bag. With the Hyperflow, I just set the pre-filter in the stream (it was so shallow the top of the pre-filter was not even getting wet, and the bottom was touching the dirt). It was the sorriest trickle of water I've ever seen. However, the Hyperflow sucked up the water like it was a roaring stream. I was worried since the pre-filter was sitting directly on the bottom, which was very fine, cloudy mud.
Day one, we quickly filtered about 9L (with zero slowing/clogging), then backflushed at the end. I only backflushed because the instructions told me to, not because of performance issues. The first 3 pumps of the backflush cycle showed significantly cloudy water coming out of the filter. It cleared up by the 4th stroke, and was perfectly clear by the tenth.
Day two, we repeated the above. No surprises, just pure filtering joy. I've never been so impressed with a filter. I PRAY that it keeps working so well. After backflushing once at home and twice in the field, it's stupid-simple. However, it REALLY helps to have a Nalgene and the supplied wide-mouth adapter. That assures you don't suck in air and cause an airlock condition. It's simple. Just start at the intake end, reverse valve one, reverse valve two, attach filter to clean water bottle with water, turn upside down and pump ten times. Turn valves back to normal position, and I'm back on the trail, when I would normally be halfway through filtering.
I will be taking it on two longer trips in the next 35 days, and will report back after those trips/tests. I will carry backup filtration/purification just in case. I am also going to figure out a way to use the filter body with my Sawyer filter cartridge (in case of filter failure). It shouldn't be hard. I might have to drill out a spare filter cartridge or something, or it might just be as simple as removing the filter (not sure if the filter body can still function without a cartridge in it, but I'll check tonight). I think the Sawyer cartridge with hose nipples (which I have) will make a great backup, and using the Hyperflow and pre-filter as a pump will keep the speed and flexibility intact.
I've heard MSR will be discontinuing this filter and moving toward gravity-based filtration (using essentially the same filter cartridge/HFM technology), but I'm sure they'll keep making the replacement cartridges.
I'm not sure why so many people have had issues, but I have my theories. One, the filter is actually crap, and I've just been lucky so far. Two, some people are not savvy enough to use this "complicated" filter. Three, once it starts slowing down/clogging, users respond by continuing filtering and pumping harder (at least until they hit the 8L mark, or fill their bottle). I actually saw some review where some guy was using his entire body weight to force water through the filter, and waiting to backflush until he hit eight liters. This pressure crams small particles deep into the filter fibers, and since backflushing is done with SUCTION (which can only achieve a fraction of the pressure of forward flow), it cannot remove the sludge that has been jammed deep into the filter fibers.
If theory three is the problem, the fix should be a simple early backflush, BEFORE it gets seriously clogged. Don't struggle to finish that fourth liter, or whatever, just STOP as soon as you notice slowing, and backflush. Yes, that's irritating, and could be time-consuming, but I have NO DOUBT that I could filter two liters AND backflush a Hyperflow before I could simply filter two liters with a Miniworks or Hiker. Crappy, filter-clogging water is rare. I'd take the extra backflushing 10% of the time to get the super-fast flow the other 90% of the time. That's assuming my theory/fix is legitimate.
I'll report back after I've had more time to evaluate the filter. I also personally know two people who have these, and have loved them after filtering many hundreds of liters. Sorry for writing a book, by the way.
A MONTH LATER:
So, since my last review and test, I've used the Hyperflow again. This time is was in North Carolina, in the Joyce Kilmer Slickrock Wilderness. For the first couple of days, the filter performed perfectly. No slowing or clogging was experienced. However, the last night, we were forced to use a very weak spring. I figured it would be a great place to put the Hyperflow to the test.
The water was clear, but it was just a trickle, and the ground over which the water was flowing had a very fine black silt. I dug a very small hole, and let it clear. The hole was just large enough to fit the pre-filter. Each time I would retract the filter (suction stroke), it would completely suck the little hole dry, even when going slowly. I knew I was getting all kinds of silty junk in the filter, but I kept going.
Around the 4 liter mark, I noticed the filter getting a little slow, so I stopped to perform a backflush. Normally, it takes about 3-5 backflush strokes before the expelled water is clear. This time it was about 8-9. After backflushing the flow was even worse than before, but still useable. It was clear that things were going downhill in a hurry. Instead of cramming more crap into the filter, I removed the filter cartridge, and installed a "blank" cartridge (which was an old one that I drilled out). Then, I installed my Sawyer Squeeze Filter (with attached hose nipples) about 3" from the Hyperflow outlet. This worked really well, and the flow rate was insane. I have no doubt that I could filter 5-6L per minute in this configuration (given adequate water flow, which this source lacked). This proved to be an awesome backup method, and only adds about 2oz to my pack.
Once I got home, I backflushed the MSR again, with similar results. I then decided to use the Sawyer faucet attachment to backflush the MSR filter with full faucet pressure. This restored it to full flow again (as far as I can remember). I still love the filter, but realize that it's too finicky for backcountry use without a backup. I will continue to carry it, but with the Sawyer as a backup. That way, I still get the fast flow and the ability to suck water out of the smallest little puddle. I am convinced the problem is that backflushing with suction just can't remove the junk that gets crammed into the filter. I will also start using an MSR Siltstopper from now on. Hope this info helps, and I'll check back in about a month when I have more info. I'm taking 7 other people up to TN/N.C. the beginning of June, and we will be using this filter (among others).