The Sawyer Select S1 is a convenient way to filter water that’s contaminated by farm runoff – as long as you don’t follow the directions.

Stats

Construction

The hollow fiber filters that Sawyer is typically known for are great at removing viruses and bacteria but they’re unable to remove chemicals (including the pesticides found in water that’s contaminated by farm runoff) or heavy metals. To address these needs Sawyer has a Select line of foam-based filters currently consisting of the S1 (green) for chemicals and the S3 (red) for heavy metals. There used to be an S2 but it looks like it was recently removed from their lineup.

Although the S1 appears to be an ordinary water bottle it’s actually a large block of foam wrapped in a translucent rubbery exterior with a cap on the top. The cap is thread-compatible with Sawyer’s hollow fiber filters including the Micro Squeeze which comes bundled with it.

For clarity, we’ll refer to the S1 itself as the “bottle” and the screw-on Micro as the “filter”.

Instructions

The reverse side of the bottle has a max fill line as well three steps for use with illustrations:

  1. Unscrew the filter, fill the bottle to the max fill line, and then replace the filter
  2. Squeeze the bottle in an alternating motion for 10 seconds
  3. Drink directly from the filter or squeeze the water through the filter into some other container

Real-World Use

The problem with the instructions is that squeezing water from the S1 with a filter attached is incredibly hard: the bottle doesn’t stay collapsed like soft-sided bladders do and the foam offers a decent amount of resistance. As a result the amount of effort required to generate enough pressure to get a decent flow rate through the attached filter is ridiculous.

The proper way to use the bottle is to leave the filter off entirely. Without the filter chemical-free water easily flows out and you can extract about 500mL or 2 cups from a full bottle in less than 10 seconds. If you put the water into some other container (a hard-sided container such as your cooking pot* is best since it requires no hands) you can then continue with your usual filtration/purification method.

*Since any water in your cooking pot is going to be boiled anyway this is safe to do

Initially I thought the S1 was DOA due to the difficulty of use, in fact while testing it on a trip I decided to forego water for half a day since my hands already hurt from squeezing water for cooking dinner and drinking the night before. Once I ditched the attached filter and put the water from the S1 into my gravity filter it became an absolute dream to use.

Foam Particles

Ironically, the water that comes out of the bottle will have a gray, almost oily look because it’s now full of foam particles. Even after filtering a half dozen gallons of distilled water through the bottle I noticed no reduction in the amount of particles nor any improvement in the appearance of the water. It turns out that passing the water through the filter is necessary not only for safety’s sake but also for appearances.

Storage

For long-term storage Sawyer recommends that you fill the the bottle with distilled water in order to prevent mold from growing inside. In fact, they recommend only flushing the bottle with distilled water at home since the chlorine in tap water will reduce its lifespan (presumably because chlorine is one of the chemicals that it removes). Long story short, you’re going to need some distilled water.