Hyperflow kit, courtesy MSR.
The technical details of this filter were fully covered in the first version of this Review. Basically, the cartridge filter has a whole mass of fine ‘micro-porous’ tubes all bundled together. The tubes have tiny 0.2 micron holes in the walls for the water to flow through: holes are small enough to block the bugs. Water is pumped from the outside of the tubes into them, to emerge at the open end. MSR call this a ‘Hollow Fiber Membrane’.
The problem with the first version, was that the walls of the tubes have a very limited area, and the fine holes were quickly blocked by the suspended matter found in any water which was not crystal clear. MSR eventually acknowledged this problem (after our first Review) and issued a statement which was added to our original review:
"We have identified a flow performance issue with some of the hollow fiber filter cartridges contained in MSR HyperFlow microfilters. The performance issue DOES NOT affect the product’s ability to filter safe drinking water, but can be frustrating, as the flow rate of the filter may not perform to product specifications. The issue has been rectified, and all filter cartridges currently in production for the MSR HyperFlow microfilter perform to flow specifications. We have worked with our retailers to replace units they have in stock that may have this issue. Any consumer that is experiencing less-than-expected flow rates on this product right out of the box or after back flushing is urged to call us at 1.800.531.9531, and we will send a valid replacement filter cartridge at no charge if the original was manufactured prior to November 11, 2008. (Please have the filter element handy, as we will ask for the serial number for our records and manufacture date verification.)"
As the cartridge tested was dated well before November 11, we requested a replacement one. A few weeks later, a complete replacement filter kit was received. The contents were identical to the first kit received, except for the date code on the cartridge inside the pump. We do not know whether all requests will be dealt with like this.
This review is concerned with testing the new cartridge in a similar manner as before.
MSR claimed with the first kit that the outlet would fit into ‘most water bottles’. This was tested with a 1.25 liter PET fizzy drink bottle (my standard free water bottle), and I could not get the outlet to fit. The instructions with the new kit made the same claim, so another attempt was made. This time, with a bit of ‘persuasion’, the outlet was fitted into the inside of the neck of the PET bottle.
The Hyperflow fitted into the neck of a 1.25 liter PET bottle.
However, for reasons which will become apparent shortly, most of the testing was done with a silicone extension hose on the outlet, as shown here. This arrangement was also used in the first Review.
The Hyperflow with an extension hose on the outlet.
In the first Review, the author used water from the dam on his farm. This is a large dam and does have some ducks living on it. The water is not sparkling crystal clear mountain water, but it is not that bad. Until the author and his family (wife and two small children) got their house and a rainwater tank built on the farm, this was their drinking water.
The water being filtered, before and after.
Here we have the dam water in a flat orange 20 liter basin. You can see a few little bits of ‘stuff’ at the bottom of the basin: this stuff is so large that the Hyperflow prefilter blocks it easily. Also shown to the right are two PET bottles of the water: one from the basin and one filtered. I would defy you to pick which is which. (The right hand one is from the filter.)
The water in the basin was allowed to settle before filtering started. Then, 8 liter of water was filtered with the MSR Hyperflow from the basin into water bottles of known volume. MSR recommends doing a backflush after 8 L, so this was then done. The MSR recommendation, which was followed, is for 10 strokes of backflushing using clean filtered water: about 0.5 L.
The first few liters of water were pumped with the filter between the author’s hands, and the water did flow very quickly at the start. But after that, things deteriorated. The stages of testing are documented below with comments. Each filtering stage represents filling one 1.25 liter PET bottle with filtered water, except for the final (6th) stage which represents a bit over one PET bottle, to make up the full 8 liters. Each backflushing stage is one stroke (of the recommended 10 strokes).
While reading the results below, it may be worth noting that the packaging for the filter still claims that the filter will handle ‘more than 3 liters per minute’. You may judge.
1. Easy pumping between hands – 1.5 seconds per full stroke, about 30 seconds/liter
2. Fairly easy pumping, as above
3. Getting a little harder
4. Getting a little harder
5. Switched to pumping vertically with one end on the ground, to get more force
6. Taking 3+ seconds for the downward stroke
1. It took ~30 seconds for the pump chamber to half-fill with water.
2. It still took ~30 seconds for the pump chamber to half-fill with water.
3. The ease of filling the pump chamber started to improve.
4. The ease of filling the pump chamber started to improve.
5. The ease of filling the pump chamber started to improve.
6. The ease of filling improved to the point where the chamber would fill to 9/10 full.
7. The ease of filling improved to the point where the chamber would fill to 9/10 full.
8. The ease of filling improved to the point where the chamber would fill to 9/10 full.
9. The ease of filling improved to the point where the chamber would fill to 9/10 full.
10. The ease of filling improved to the point where the chamber would fill to 9/10 full.
11. It took 10 seconds to 3/4 fill, and 15 seconds to fill to 9/10.
My wife trying out the filter.
1. Despite the backflushing, the pumping was still hard: 2.5 – 3 seconds per downward stroke.
2. As above, after a brief attempt to pump ‘between hands’.
3. Getting a little harder.
4. Gave my wife a go: she said the force was OK if she took 8 – 10 seconds per downwards stroke.
5. Tolerable downwards force needed at 6 – 7 seconds per stroke.
6. Tolerable downwards force needed at 6 – 7 seconds per stroke.
1. It took only 4 seconds for the pump chamber to 3/4 fill with water.
2. As above.
3. As above.
4. As above.
5. As above.
6. As above.
7. As above.
8. Possibly even slightly easier still, but not by much.
9. Possibly even slightly easier still, but not by much.
1. At the start, a 4 second stroke was managed, but this had become 6 seconds by the end.
2. As above.
Pushing on (or downwards) with the testing.
You may notice in the photo here that I have taken off my thongs. That is because I was using one of them between the pump base and the ground. Without that buffering layer of foam, the bottom of the pump was steadily drilling into the soil. A lot of shoulder weight was being used to get the water through the filter. Anyhow, at this point my wife declared it was coffee time. I was getting a bit tired around the shoulders, so I willingly gave up. I could not see any point in continuing the testing: there would be no sudden miraculous improvement.
The inside of the filter cartridge was carefully inspected before and after each backflushing stage. Because I knew what to look for, I was able to see a very faint green/brown tinge on the surface of the filter tubes, but it was so faint that a casual user might not see it. It did seem that the same tinge was there before and after the backflushing cycles, meaning that the backflushing process was not able to remove it. This by itself calls into question the effectiveness of the backflushing process for handling typical organic ‘stuff’ in a water supply. That the backflushing process did not seem to have much effect on the pumping force anyhow, supports that doubt.
The first one or two bottle-fulls were pumped very easily. In fact, the first half of the first bottle was pumped so easily I did briefly wonder whether there was a filter cartridge there at all. The same ease of filtering has been reported with crystal clear mountain water by some users. It seems highly likely that if all the water supply contains is pure water and various bacteria and protozoa, then the filter would provide excellent service. It would be a fool who expected to encounter nothing but such perfectly clear water.
The first backflush cycle was, to my surprise, extremely difficult to get going, right from the very start. Yes, it was being done with filtered water. I do not believe that anything could have got into cartridge via the clean water to block up the inside of the micro-porous tubes. More startling was the discovery that the second backflush cycle was much easier to do. I have no explanation for this at all. However, as may be seen from the results above, backflushing did not seem to clear much of the muck (whatever it was) off the inlet face of the filter, despite my best efforts.
It could be argued that filtering 20 liter of water is hardly a good test of the filter. This would be true if the filter had worked well. But since the filter died almost at once – after the first couple of liters, I do not think further pumping would have proven anything I had not already discovered.
I mentioned in the first Review that I had also tried pumping this dam water through a Katadyn Hiker filter with no problems. I wrote there that the Hiker is widely regarded as the benchmark filter against which other filters are often compared. It uses a large pleated filter with a very long life, even on this sort of water. (That was tested.) It is my considered opinion that despite all the technological marvels embodied in the micro-porous tubing in the MSR Hyperflow, nothing substitutes for a multi-layer filter with a *big* surface area. The surface area on the MSR Hyperflow is just not big enough, and there is only one filter layer: the finest.
In the first Review, I wrote that the design of the MSR Hyperflow is nice; the filter is light, and that it works well with crystal clear water. All that is true, but many water supplies are not crystal clear, and the revised MSR Hyperflow cartridge still fails with less than perfect water, despite the changes.
The packaging still claims a flow rate of ‘more than 3 liters per minute’ I was struggling to get a flow rate of one tenth of this after filtering a few days worth of water. This claim is not credible.
We know that MSR is aware of this problem, is concerned about it, and has attempted to address it. The new cartridge is better than the old one, but it is still quite useless for any walker who has to deal with unknown and variable water supplies.
|various plastics and polymers|
|various plastics and polymers|
|0.2 micron. Claimed to remove bacteria and protozoa to a degree which meets EPA requirements for water purification. This does not include viruses.|
Claimed filtering rate:
|‘more than 3 liters per minute’|
Measured filtering rate:
|down to about 1 liter in 2 minutes, despite backflushing and force|
|can be down to 20 L if water not crystal clear|
|~220 g (7.8 oz) for minimal kit of pump, full-length hose and inlet filter|
|Filter Kit: US$99.95|
Replacement cartridge kit: US$39.95
Replacement prefilter: US$14.95
Maintenance kit: US$19.95
What’s Good (from here and the previous review)
- A fairly low weight
- A neat design
- Can be repeatedly backflushed
- Useful inlet filter
- Cartridge and inlet filters can be replaced
- Removes bacteria and protozoa to EPA specifications
What’s Not So Good (from here and the previous review)
- Quickly blocks with any water which is not perfectly clear
- Valve design can collapse under pressure
- Nalge bottle connector is not ergonomic – and leaks
- Needs an outlet hose added to the kit
- Unsafe for winter use when freezing is possible
- Silicone grease for the O-ring is not included with the kit
- Does not remove viruses (most microfilters have this limitation)