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Reviews > Water Treatment > Filters > Sawyer S1 Select Water Filter > Test Report by Mike Lipay

Sawyer - S1 Water Filter
Mike Lipay

Reviewer Information

Location:Plum, Pennsylvania, USA
Height:5' 6" (1.6 meters)
Weight:162 lb (73.5 kg)
Background:I’ve been hiking since ’65 with occasional backpacking trips (backpacking became a love affair in the early 80’s). My first sleeping bag weighed in at 8 lb (3.6 kg) by itself! These days my loaded pack only weighs about 15 lb (6.8 kg) sans food. While most of my adventures are in the Northeast I’ve also been spending a good deal of time in the desert Southwest and most places in-between. My trips tend be in the cooler months - September through May - as I’m not much of a hot-weather person.

Initial Report - October 30, 2021

The Sawyer S1 Water Filter is an interesting concept in water filtering. Instead of the usual pump action or gravity feed filters this one works by squeezing the soft-sided bottle until the water has been fully filtered, according to Sawyer this takes 20 squeezes. The S1 Water Filter goes beyond filtering for the usual bacteria and viruses, it also filters out chemicals and pesticides, short of spending a couple hundred dollars for a lab test I’m not sure how one would verify the efficacy of the last two items.

According to the packaging the Sawyer S1 Water Filter accomplishes this by using a 0.1 micron Hollow Fiber Membrane combined with a proprietary Foam membrane. In additional a carbon filter is used for both additional filtering and taste. Filtering can take as little as 10 seconds, and reduces the contaminants below current EPA standards.

Product Information

Manufacturer: Sawyer Products, Inc.
MSRP: $47.50 USD
Filter Material: 0.1 Micron Absolute Sawyer Micro Squeeze Filter
Longevity: Up to 1600 uses
Removes: Bacteria, Protozoa, chemicals, pesticides

Manufacturer Measurements

Height: 8.5 in, 22 cm
Width: 14 in, 35 cm
Length: 3 in, 8 cm
Filter Weight: 0.625 lbs, 283 g

Personal Measurements

Height (bottle): 10-5/8 in, 27 cm
Height (w/filter): 14-1/8 in, 36 cm
Width: (bottle): 2-5/8 in, 7 cm
Bottle Weight: 8 oz, 218 g
Filter Weight: 2 oz, 53 g
Assembled Weight: 9 oz, 269 g
Primed Weight: 15 oz, 416 g

Initial Impressions

The Sawyer S1 Water Filter comes with for items (as seen in the photo): a syringe for back flushing the filter, the filter itself, a ring for attaching a standard soda-style water bottle (also for back flushing) and the Sawyer soft-sided foam-filled water bottle.

The Sawyer S1 Water Filter is good for an estimated 1,600 uses, or between 250 and 273 gal (946-1,035 L). Personally, that is way beyond my abilities to actually track so I will probably figure on replacing it every 5-6 years, which seems a reasonable amount of time for the cost.

The bottle itself is soft sided, required to accomplish the squeezing needed to filter the water (an interesting procedure which I will get into). When fully assembled I find it a bit tall for comfortable usage and carrying (see image to the left, Sawyer S1 next to my usual water bottle); the bottle holder in my pack, and the leather hip holder I use were not built with a bottle this tall in mind, I will be curious to see how they handle it. The material itself feels odd (rubbery), and does seem to pick up dust and other small particles lying around, I will be curious to see how this does in the outdoors.

The Sawyer S1 Water Filter has to be primed before its first use. This is to flush the system of small bits of absorption material that may have entered the bottle during manufacture, or come loose during shipping. While not harmful the material may leave a metallic taste in the water, and may prematurely clog the filter, requiring back flushing sooner than what is normal. The procedure to prime the system is to fill the bottle halfway, attach the filter to the bottle, squeezing the bottom then top of the bottle to force the water through the filter (repeat 10 times); next remove the filter, fill the bottle to the fill line (hard to see), replace the filter and squeeze the bottle again for another 10 times; finally remove the filter, invert the bottle and roll the bottle up from its bottom to squeeze as much of the water out of the bottle as possible. The bottle is now ready for use.

About the priming, it sounds easier than it was. The instructions that come with the bottle say that it will hold 20-22 oz (591-651 ml) so I measured out half of that in a measuring cup and began pouring it into the bottle, two things quickly became apparent: you can’t see the amount of water in the bottle because of the filter medium; it took in very little before it began overflowing, seems the medium inside the bottle takes a while to absorb the water. I found that if I slightly squeezed the bottle at the top then slowly released the bottle while pouring in the water that I could get a lot more into the bottle before it “filled up”. After filling halfway (by measure still couldn’t see a water level) I put the filter on the bottle and began squeezing, after 10 times I filled the bottle (again, by measure) and repeated the squeezing. After I finished the priming I removed the filter and squeezed out as much water as I could. I then weighed the bottle out of curiosity, empty but primed the bottle (with filter) weighs 15 oz (416 g), pretty hefty for an empty bottle.

I already have a few concerns about the bottle, first (as stated above) is the height, primarily if either of my bottle holders (pack or hip) will hold the bottle while hiking. The second is in filling the bottle, the photos on Sawyer’s website show the bottle being partially immersed in the water to fill it, based on the priming I’m not sure that immersion alone will be enough to fill the bottle. The instructions for use say to remove the filter, immerse the bottle and fill to the fill line, replace the filter and do the squeeze procedure (squeeze lower half, upper half, repeat 10 times), the replace the filter and either drink from the bottle or squeeze it into another container. Doing it this last way is similar to using a gravity filter in that it is necessary to carry two bottles in order to filter the water, only this setup is heavier than a gravity setup.


Because of its unique makeup cleaning the Sawyer S1 Water Filter is a bit different than most filtration systems, not difficult, just unique.

First, the bottle itself, with the integrated foam filter, is the part with the limited lifetime as the foam filter cannot be 100% cleaned, as with a pump filter debris will accumulate in the foam clogging the foam at some time, how soon will depend on the cleanness of the water. No instructions are given for cleaning the bottle itself.

Second is the cleaning of the filter, and for the two methods are provided, which one used is purely the decision of the owner, both methods are outlined here:

  1. Obtain about 1 quart (1 L) of clean water (such as tap or bottled water).
  2. Remove the black filter from the water bottle (careful not to loosen the black cap on the bottle, it’s difficult to put back on properly).
  3. Unscrew the white cap from the filter.
  4. To back flush using the syringe:
    1. Fill the syringe with clean water.
    2. Attach the syringe to the drinking side of the filter.
    3. Force the water through the filter by depressing the plunger on the syringe.
    4. Repeat until the water coming out is clean, and it flows through easily.
    5. Remove the syringe and reassemble the bottle and filter.
  5. To back flush using the water bottle method:
    1. Fill the water bottle with clean water.
    2. Screw the blue coupling onto the water bottle.
    3. Screw the other end of the blue coupling onto the drinking side of the filter.
    4. Turn the assembly until the bottle it upside-down.
    5. Squeeze the bottle to force the water through the filter until the bottle is empty.
    6. Continue forcing clean water through until the water comes out clean and flows through easily.
    7. Disassemble the cleaning system and reassemble the S1 bottle and filter.

Free Gifts

I don’t know how long it will continue, but the Sawyer S1 Water Filter arrived with two free gifts:

A bottle of Sawyer Picaridin Insect Repellent for use on the skin. The bottle claims to repel mosquitoes and ticks for up to 14 hours if used as directed.

And a bottle of Sawyer Permethrin Insect Repellent that is to be applied to clothing. This promises to repel ticks and mosquitoes for up to 6 washes when applied as directed. I have used this in the past and find that it does do a decent job.


Field Report - Dec 29, 2021

Never go into the field with new equipment without first using it at home. I’ve lived by this mantra my entire hiking life, and the Sawyer S1 Water Filter is one example of why. At first I thought using it would be just like any other bottle: tip it up and sip, ‘taint so. Doing it this way I found it very hard to draw water just by drinking, I got a little bit that way, the amount that wasn’t inside the foam, once I drank it there was no more easy water to drink, I had to get the water out of the foam by squeezing it to release water from the foam. I am beginning to think that this is not the way to go with the S1, the other option is to fill it up then force squeeze the water into another bottle for drinking. I will continue to test it both ways over the coming months to see if things change as it ages, and as I get used to it.

Regarding the filtering, I filled the bottle up with bottled water that contains calcium, salt, and other minerals meant to “improve the taste”. Personally, water, like vodka, shouldn’t have much of a taste, which is why I tend to avoid bottled waters that contain additives (and flavored vodkas). The Sawyer S1 water filter did a good job of removing these additives and restoring the “real taste” of water. I am both impressed and pleased with the filtration ability.

After reading the instructions, and looking at the product on their website, I noticed that the cap I have is different from what is described and shown, I don’t know how this may affect my experience with the product versus having the cap that was described, this should be noted and kept in mind. The cap that the instructions talk about is a push/pull cap, where what I have is a flip-top cap, this could affect some aspects such as drawing water while drinking.

Date Location Length / Altitude Weather
Oct 14, 2021 Roaring Run Wild Area, Pa 7.8 miles, 12.5 km 64-73F, 18-23C, Cloudy
I usually hike RRWA when I test a filtering system, the trail crosses the run 28 times with different water levels and flows all along, so there are plenty of opportunities to fill and refill along the way. During this trip I noticed a few issues with the S1, note the photos and comments below.

Filling the bottle wasn’t as easy as submerging it in the water and waiting for it to fill, the foam prevents it. I found that squeezing the bottle to let air out, then releasing it, would allow me to fill it more completely.

It’s hard to see both the fill line and the water level. The fill line is about 1/4 inch (6 mm) above the words Step 1. After squeezing and filling a couple times the actual water level was just about where my thumb is (see the dark area on the left side of the bottle).

I typically carry a water bottle in a hip holster, with the S1 the bottle continually knocked against my elbow while I hiked, very irritating. I tried putting it in my backpack but the bottle, because of how much was above the bottle pocket, would fall out on occasion.

In addition to these issues, I still find that drinking straight from the bottle is difficult. With so much water in the foam I couldn’t just drink, I had to squeeze the bottle to force the water out. Even then there were times when the water level in the bottle was too low to easily squeeze and drink. The other option for using the S1 is to squeeze it directly into another bottle or pouch, I will try those methods on future trips.

Dec. 11-12 Laurel Highlands, Pa 15.5 mi (25 km)
854-2468 ft (260-752 m)
28-45 F (-2 to 7 C); calm; cloudy.
I didn't get much of a chance to use the Sawyer S1 on this trip, I stopped at a stream to fill up my water bottle and had a failure of the S1. I filled the S1 in the stream, did the squeezing to filter the water, then inverted it and squeezed to fill up my water bottle. After rolling the S1 down two times the cap popped off of the S1 and unfiltered water poured into my water bottle. I stopped using the S1 at this point, I will include more on this in the notes below.
Dec 26, 2021 Laurel Hill State Park, Pa 11.9 mi (19 km) / 1,917-2,465 ft (584-751 m) 38-41 F (3-5 C). Brisk breeze at 5-8 mph (8-13 kmph) gave a windchill of 32-38 F (0-3 C), cloudy.
I stopped by a stream at the start of the hike to fill up my water bottle (32 oz / 1 L). it wasn't easy. The S1 filled up easily from the fast-flowing stream, and squeezing the S1 to run the water through the carbon filter was easy as well, but that's where the ease ended.
Squeezing the water out of the S1 into my water bottle was hard, and the water coming out of the squeeze filter sometimes came out as drops instead of a stream. It took a lot of squeezing and crunching to get most of the water out, and it took three attempts to fill up the water bottle. Even though the S1 is supposed to hold 20 oz (0.6 L), it was just too hard to squeeze out every drop. Since I didn't have this problem on warmer hikes, I'm guessing it is harder to squeeze the silicone bottle enough to get the most out.

Additional Notes:

As I said above, the cap on the S1 popped off when I was trying to fill up my water bottle. When I got back home I contacted Sawyer about the issue, their response was to: flush bottle itself with clean water (note: tap water cannot be used because of the chemicals, so I had to use purified bottle water), then back flush the squeeze filter. After this securely fasten the cap and check prior to each use that the cap is firmly attached, then let them know if the issue occurred again. Problem is, I have never removed the cap, so it became loose on its own. I'm a bit wary about using the S1 on future backpacking trips, so I plan on carrying an alternate filtering system in case this should happen again.


What I like about the Sawyer S1 Water Filter:

  • Removes more contaminants than any other filter I have used.
  • I like being able to drink straight from the bottle, instead of having to carry a drinking bottle in addition to the filter system.

What I don't like about the Sawyer S1 Water Filter:

  • In cold weather the silicone filter bottle is hard to squeeze the water out.
  • Difficult to see how much water is in the bottle, I see this as a problem knowing when to refill.
  • Seems a bit tall for carrying in the bottle holders I have.
  • The black cap that is not supposed to be removed unscrews easily when removing the filter. Have to remember to hold the cap while removing the filter (and not the bottle).
  • The filter cap popped off of the bottle while filling my water bottle, contaminating the bottle.


This ends my Field Report, I’d like to thank Sawyer and for the opportunity to test the S1 Water Filter. Check back in a couple months for my Long Term Report.

Read more reviews of Sawyer Products gear
Read more gear reviews by Mike Lipay

Reviews > Water Treatment > Filters > Sawyer S1 Select Water Filter > Test Report by Mike Lipay

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