Review of Sawyer Select S2 Water Purifier – fast, effective virus & chemical removal

Viruses, pesticides & harmful chemicals in water are a concern for international hikers, and even areas in the US! Sadly, until recently there were no inexpensive & lightweight water purifiers that could handle all these contaminates. But a few months ago Sawyer solved this dilemma with their new Sawyer Select S2 Water Purifier Bottle. It removes viruses, bacteria, protozoa, harmful chemicals, and pesticides. Best of all, it does this in an inexpensive and easy to use bottle weighing only 10 ounces.

What’s Great About It

The combination of removing protozoa, bacteria, and viruses and pesticides, and other harmful chemicals (and even heavy metals like lead & mercury) is what sets the Sawyer S2 and S3 purifiers apart from all others. Few if any purifiers can remove all these contaminants, and certainly not at their low cost and weight. And surprisingly, you can start drinking purified water in just 10 seconds. It’s that easy!

The Sawyer Select S2 Water Purifier Spec’s

  • Removes 99.99% of viruses, 99.99999% of bacteria, 99.9999% of protozoa, cysts, chemicals & pesticides
  • Reduces chemicals to 0.5 parts per billion, up to 40 times lower than the EPA’s maximum rec. level
  • Reduces pesticides to 0.01 ppb, up to 400 times lower than the EPA’s maximum rec. level
  • Weight dry: 9.2 oz (260 g) on my scale — wet after use 13.0 oz (270 g)
  • Time to treat 10 sec. Time to drink from bottle immediate. Time to squeeze ~30 sec. for 20 oz capacity.
  • Cost: $80 at REI

Note: The S2 Purifier has only been out a few months. As such this is an initial/short term review . Longevity and long term use has not yet been tested/determined.

Compared To the Sawyer Squeeze System

Sawyer Squeeze Filter (and Sawyer Mini)

The Sawyer Squeeze Filter (and Sawyer Mini) both eliminate protozoa and bacteria. But they don’t eliminate viruses, chemicals, pesticides, or heavy metals. And they don’t improve the taste or odor of the water. The Sawyer S2 eliminates all of these with the exception of heavy metals. (You have to upgrade to the S3 for heavy metal removal.) On the plus side, the Sawyer Squeeze has a much longer useful life, is much lighter, and costs less than the S2.

TIP: Soon you can convert your current Sawyer Squeeze Filter into a Sawyer Select S1, S2, or S3 Purifier by purchasing just the bottle and foam. This will save you $15 over the full system. [bottle & foam only option currently not available but Sawyer says they are coming soon] See more here…

Compared To Other Purification Methods

Pump Water Purifiers that remove viruses

Pump Filters that remove viruses like the MSR Guardian Purifier are quite expensive and heavy ($350 and over a pound). And even then the MSR Guardian Purifier does not eliminate chemicals, pesticides, or heavy metals. Note: most other less expensive pump water purifiers also do not eliminate viruses in addition to not removing chemicals, pesticides, or heavy metals. E.g. the bestselling MSR SweetWater Microfilter Water Filter and Katadyn Hiker Pro Clear Microfilter.

Chemical water purification

Chemical treatments don’t eliminate harmful chemicals, pesticides, or heavy metals. They are also not 100% effective in turbid water. The Sawyer Select S2 Water Purifier Bottle is much faster. Water is purified & drinkable in 10 seconds. In comparison, chemical treatments can take up to 4 hours to fully purify water. And you have to carry that water around with you until it’s fully treated. That means you’ll unnecessarily carry 2 to 6 pounds of water in your pack. Finally, chemical treatments leave a taste & some hikers don’t like introducing chemicals into their body.

UV Sterilization

UV sterilization e.g. the SteriPEN eliminates protozoa, bacteria, and viruses in a few minutes. But it doesn’t eliminate chemicals, pesticides, or heavy metals. Another downside: UV pens don’t have a good reputation for battery life & treatment capacity in the field. Finally, UV doesn’t work well with muddy, turbid water. In this case, you’ll have an added step of pouring your water through a pre-filter before using the SteriPEN.

How Does the S2 Work?

A new proprietary Adsorption Technology Foam1 is the key to the Sawyer Select S2 Water Purifier and is what sets it apart form the competition. The S2 Water Purifier consists of three main parts:

  • Flexible silicone bottle that holds proprietary adsorption foam.
  • Adsorption Foam Purifier Material1. This proprietary adsorption foam is the first stage of purification. It does almost all of the removal of harmful chemicals, pesticides, and viruses (e.g. Hep A, Hep E, Rotavirus, etc.).
  • Micro Squeeze Filter2 on top of the bottle. This is the second stage of purification. It removes bacteria (e.g. E coli, typhoid fever, cholera, etc.) and protozoa (.e.g giardia, cryptosporidium. etc.); as well as particulate matter & sediment.

1 The proprietary Foam Adsorption Technology used in Sawyer Select S2 Water Purifier (and S1 and S3 filters) was developed by a partnership between Sawyer and Foamulations LLC . It safely removes contaminants like chemicals, pesticides, and viruses (and heavy metals – S3 only). Adsorption filtration is the process in which harmful chemicals and viruses adhere to the surface of the adsorbent foam membrane. They are permanently captured (adhered to the foam) and neutralized.

2 The new Micro Squeeze Filter is the same diameter and the same flow rate as the Sawyer Squeeze Filter but is shorter and lighter. It uses the same 0.1 micron “Absolute Hollow Fiber Membrane.”

How to Use the Sawyer Select S2 Water Purifier

Sawyer Select S2 Water Purifier

TIP1: The only thing I would add to these instructions is to use something like a widemouth 20 or 24 oz sports drink bottle to accurately pour water into the 0.75″ diameter opening of the S2 bottle. This 1) makes it easier to collect the water from a stream or lake. And 2) it allows you to make a clean pour without having any contaminated water dripping down the sides of the bottle. That way you can immediately drink from the S2 without worrying about untreated water dripping from the side of the bottle and into your mouth. [For fastest filling, it helps to hold the bottle at a slight angle when you pour the water in.]

Sawyer Select S2 Water Purifier Bottle

Use instructions are right on the side of the S2 bottle.

Useful Life, Cleaning and Storage

Useful Life

The S2 bottle and foam filler last for 800 uses. That’s about 125 gallons.  After that you can replace just the bottle and foam. Note: this is also an upgrade option for Sawyer  Squeeze Filter owners.

  • Replacement bottle for S1 – MSRP $44.99
  • Replacement bottle for S2 – MSRP $64.99
  • Replacement bottle for S3 – MSRP $74.99

The Micro Squeeze Filter on top of the bottle has a useful life similar to the Sawyer Mini Filter’s or about 100,000 gallons (with backwashing as necessary).

S2 Bottle – Cleaning and Storage

A surprise, but the bottle and foam inside need no backwashing or sterilization between trips. Just squeeze out the excess water from the foam and stow the bottle covered with either the Micro Squeeze Filter or supplied white cap. That is, it’s best to keep the foam damp while in storage. Proprietary ingredients in the foam prevent bacteria and mold growth or bad smells developing. The S2 Bottle is not damaged by freezing.

Micro Squeeze Filter – Cleaning and Storage

Sawyer’s recommendations for post trip maintenance are the same as for the Sawyer Squeeze Filter. So while not absolutely required, it’s a good practice after trips to  backwash the filter, sterilize it with a weak bleach solution and then let it air dry. This will promote filter longevity and maximum flow rates. [Instructions are on the outside of Sawyer Squeeze pouches.]

The Micro Squeeze Filter must be kept above freezing when wet. Water freezing in the filter can destroy the hollow fiber membrane. The easiest way to prevent freezing is to put the filter in a Ziplock bag and keep it in your pants pocket or other warm area during the day. And/or sleep with it at night.

Comparison of the S1, S2 & S3 Water Purifications Systems

The S1, S2 and S3 all have the same components (squeeze bottle, adsorption foam, and Micro Squeeze Filter). What varies is:

  • Contaminates removed: S1 removes the least and S3 removes the most including heavy metals.
    (The exact formulation of adsorption foam is what controls the contaminates removed)
  • Useful life: S1 lasts the longest at 1600 uses, and S3 the least at 400 uses.
  • Cost:  S1 costs the least at $60 & S3 costs the most at $90.

Sawyer Select S2 Water Purifier

Other Reading

The Best Hydration – Drink When Thirsty

Drink When Thirsty debunks the many myths about hydration and dehydration like “If you are thirsty, it’s already too late” and  “If your urine is yellow, you are dehydrated.” This medically sound and well-researched article suggests that Drink When Thirsty is the best and healthiest strategy for hydration during exercise.

Drink When Thirsty


  1. This post contains affilate links. If you make a purchase after clicking on the these links, a slight portion of the sale helps support this site at no additional cost to you.  I am never under an obligation to write page post a review about any product. Finally, this post expresses my own independent opinion.
  2. The manufacturer provided the author a sample of this product for review.