Water Treatment 101: Demystifying Backflushing

Just about every water filter out there requires that you clean its cartridge after a certain number of liters to restore its flow rate. Cleaning your filter regularly also extends its lifespan. For some filters, this is done through backflushing—which is required for the MSR AutoFlow, HyperFlow, TrailShot and Thru-Link microfilters. While the process might sound intimidating, we’re here to debunk that myth and show you just how quick and easy backflushing can be in the field—no tools required.

Giving your water filter a quick backflush will keep it running at its optimal rate, and ultimately save you time when it comes to treating your water each day of the trip.

What backflushing does:

The AutoFlow, HyperFlow, TrailShot and Thru-Link microfilters all use hollow fiber technology to filter your water. As the water flows through the walls of these fibers, contaminates are trapped inside. Backflushing dislodges and discards the contaminants, allowing the water to flow freely again. It’s especially important to backflush if you’re filtering water from cloudy or tea-colored sources, as the particulate can build up quickly.

Learn how to backflush your AutoFlow, Hyperflow, TrailShot or Thru-Link microfilter, as we walk you through the simple steps in these videos.

How to Backflush the MSR AutoFlow Filter

  • To backflush, start by filtering at least a half-liter of water into a reservoir, such as an MSR Dromedary bag.
  • Remove the inlet hose from its barb on the male disconnect, then hold or hang the clean reservoir above the filter cartridge, and allow the water to flow back through the cartridge and out the inlet tube. Allow at least a half-liter to flow through the filter cartridge to remove any debris collected in the fibers.

How to Backflush the MSR HyperFlow Filter

You’ll want to perform the backflushing process in a controlled area so, as not to lose any small parts.

  • Start by removing the clean side cover cap and attaching it to the Quick Connect bottle adapter.
  • Then filter at least a half-liter of water into a reservoir or water bottle.
  • Remove the inlet hose and unscrew the pump inlet from the pump cylinder. Make sure not to pump any air through the filter at this time.
  • Reverse the large check valve and reinstall it inside the pump inlet.
  • Pull the pump cylinder to the end of a stroke and turn it clockwise until the piston locks.
  • Then use the cylinder to unscrew the piston from the filter cartridge.
  • Pull the small check valve out, reverse it, and reinstall it inside the piston.
  • Now carefully thread this pump cylinder onto the filter cartridge.
  • Thread the pump inlet back onto the pump cylinder. Again, don’t pump any air through the filter.
  • Now you’re going to pump water through the filter to flush the cartridge. Pump at least 10 full strokes of filtered water. Wait for the cylinder to fill with water during each stroke.
    • If you’re using a hard bottle, such as a Nalgene, invert the container to keep air away from the outlet.
  • When you’re done, disassemble the pump and reinstall the large and small check valves in their original forward flow position.
  • Dry off the pump and then reassemble it.

How to Clean the MSR TrailShot Filter

  • Start by simply pumping water until the bulb is half full.
  • Then shake the filter up and down for 20 seconds.
  • Remove the inlet hose from the nozzle and squeeze the dirty water out.
  • Then reconnect the hose.

If cleaning the filter fails to restore water flow replace the cartridge.

How to Clean the MSR Thru-Link Inline Filter

  • With the filter installed suck on the bite valve to pull water through the filter, filling the drink tube with filtered water.
  • Detach the filter from the reservoir.
  • Blow into the bite valve, pushing all the water back through the filter.
  • Reattach the filter to the reservoir.
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