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.


  • Introduction
  • Preliminary
  • Performance Testing
  • Results
    • Filtering
    • Backflushing
    • Filtering
    • Backflushing
    • Filtering
    • Other Observations
  • Summary
  • Specifications: Manufacturer:, Year/Model:, Manufacture:, Materials:, Filter specification:, Claimed filtering rate:, Measured filtering rate:, Filter life:, Weight:, MSRP:
  • What's Good (from here and the previous review)
  • What's Not So Good (from here and the previous review)

# WORDS: 2200

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