Review: We Sawed a Sawyer Squeeze Water Filter in Half!

Sawyer Flow Rate

Many long-distance backpackers use the Sawyer Squeeze water filter. This is because it is ease to use, lightweight and durable.

We wanted to get an INSIDE look at the Sawyer Squeeze to see how it really works. So we cut one open and took a close look with a microscope.


Read our series of Sawyer filter reviews:

Review: the new Sawyer Micro Squeeze

Sawyer Squeeze and Micro Squeeze Flow Rate Tests

Should I Carry the Sawyer Syringe?

Ryan filtering water into his water bottle using the Sawyer Squeeze.

Here is what we did...

Collecting contaminated water from a pond

We filled the Sawyer filter bag with some murky pond water.

pushing the water through the Sawyer Squeeze filter

Then we forced pond water through the Sawyer Squeeze into a water bottle.

Backflushing the Sawyer Squeeze to remove debris from filter

Next we backflushed the Sawyer Squeeze with clean water.

Squeezing the filter bag

Filtering pond water into a water bottle.

backflushing the Sawyer Squeeze

Backflushing the Sawyer Squeeze with clean water.

We disassembled the filter

We drilled out the locking points on the side of the filter.

Here is a view of the water intake side of the filter.  This is the side that the dirty water flows into.

Then we unscrewed the filter and removed the internal filter.

And here is a view of the outflow side of the filter.  This is where the clean water flows out of the filter.

Microscopic View

We bought a microscope and hooked it up to a laptop to get a close up view of the filter.

Clean Side of Filter

Focusing the microscope on the outflow or clean end of the water filter.

Outflow Tubes

The microscope reveals the small outflow tubes, where the clean water comes out.  A solid resin keeps water from flowing around the tubes.

Microscopic View

Here, we set up a microscopic view of the long filter loops where the water flows into the filter.  Notice some dark particulate matter stuck to the sides of the loops.  Backflushing the filter removes these contaminants.

Final disassembly: saw in half!

To get a closer look at the long filter loops we removed the plastic housing that protects the filter from being damaged.

microscope and light focused on the hollow fiber tubes.

Now you can see the long filter loops (some tubes were damaged during the disassembly process).  Each long filter loop is secured to the outtake section (clean part) of the filter. This is the portion covered by protective tissue in the photo.

microscopic view of the hollow fibers that make the filter work.

The microscope reveals contaminants stuck to the side of the long filter loops.

a close up of the hollow fiber tubes, debris captured on the outside of the tubes.

The Filter Process

Contaminated water comes into contact with the outside of the long, looped filter tubes. The pores on the side of the tubes are so tiny (0.1 microns or 0.0001 millimeters), that bacteria (0.2 microns to about 3 microns) and Giardia (7 to about 10 microns) can’t pass through the filter. Water enters the wall of a tube through these small pores and comes out the end of the tube as purified water. Bacteria, Giardia, and debris are simply too big to pass through the pores. When the pores get clogged with debris and contaminants, the flow rate of the filter decreases. To increase the flow rate of your filter, backflush the filter to remove the debris and contaminants.