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Reviews > Water Treatment > Filters > Sawyer S3 Select Water Purifier > Test Report by Nancy Griffith

December 30, 2021



NAME: Nancy Griffith
EMAIL: bkpkrgirlATyahooDOTcom
AGE: 55
LOCATION: Garden Valley, California, USA
HEIGHT: 5' 6" (1.68 m)
WEIGHT: 130 lb (59.00 kg)

My outdoor experience began in high school with a co-ed scout group which made a 10-day canoe voyage through the Quebec wilds. I've been backpacking since college in Pennsylvania. I have hiked 1/4 of the Appalachian Trail and 2/3 of the Pacific Crest Trail. My typical trip is in the Sierra Nevada from a few days to a few weeks long. My base weight is lightweight at 15 lb (6.8 kg) while still using a tent, stove and quilt. Longer mileage summer trips are now stoveless.



S3 complete set
Complete S3 Set
ready to fill
S3 Bottle
micro squeeze
Micro Squeeze
Manufacturer: Sawyer Products, Inc.
Year of Manufacture: 2021
Manufacturer's Website:
MSRP: $79.99 US

Listed Weights:
S3 bottle: 10 oz (283 g)
Micro Squeeze Filter: 1.8 oz (51 g)

Measured Weights:
S3 Bottle: 8.0 oz (228 g)
Micro Squeeze Filter: 1.9 oz (53 g)
Plunger: 1.0 oz (27 g)
Adapter: 0.2 oz (5 g)

Listed Volume of S3 Bottle: 20 oz (0.6 L)

Listed Size: 8.5 in x 14 in x 3 in (22 cm x 36 cm x 8 cm)
Actual Size: 2.5 in x 2.5 in x 10.75 in (6 cm x 6 cm x 27 cm)


The Sawyer S3 Select Water Purifier is a two-stage water purification system. The S3 silicone bottle contains a foam purifier that is able to remove chemicals, pesticides, heavy metals and viruses. There is a cap to close off the bottle without having the filter screwed atop. The Sawyer Micro Squeeze filter on top is able to remove pathogens along with any other sediment, particulate, and microplastics.

The Micro Squeeze filter is a 0.1 micron hollow fiber filter that screws onto standard (28mm/1.1 in) bottle tops including the S3 silicone bottle. It is also sold separately and can be used separately when only filtration is needed. It is rated for 100,000 gallons of water filtration.

The S3 silicone bottle adds another level of purification when needed. It consists of a very pliable silicone bottle which is filled with a foam purifier. The foam uses adsorption to trap heavy metals, chemicals, pesticides and viruses into the membrane. The S3 Bottle is rated for 400 uses. It is also sold separately when a replacement is needed.

The whole thing works by filling the bottle with water to be treated, screwing the Micro Squeeze Filter atop, squeezing the bottle for 10 seconds and then dispensing the water into another container.

Also included is a cleaning plunger and cleaning coupling to backflush the Micro Squeeze Filter. The plunger fits into the clean side of the filter or the coupler can be used to backflush from another bottle of clean water.


initial fill
squeeze to fill
Squeeze to fill
The Sawyer S3 Select Water Purifier came as a complete set which includes the purifier bottle along with the squeeze filter and a plunger and coupler to assist with backflushing the filter. I liked seeing a written instruction sheet even though I was already online checking out the Sawyer website. My initial impression is that this product was well thought out and complete.

After I weighed the components, I followed the instructions for initial use given on the enclosed sheet. It says to fill the bottle 1/2 way, squeeze 10 times, fill to max fill, squeeze 10 times and dispense the water. I saw on the video that chlorinated tap water may reduce the life of the foam so I used bottled spring water and a measuring cup. First off, filling the bottle was slow going. After only one or two ounces, the bottle was overflowing. The foam needed to absorb water and air in the foam kept bubbling up keeping the water from flowing in. I was able to get 13-14 oz of water into the bottle before it hit max fill. It took a little searching to find the max fill line since it is embossed in small font on the bottle in the same material and color as the bottle. Now that I know where it is, I'll fill to just above the foam which is easily visible since it is dark colored and can be seen through the bottle wall.

Dispensing the water only poured out 12 oz so I'd say that ounce or two was what was normal residual held in the foam.
initial water dispense
Water from Initial Dispense
The dispensed water was grey and I could see black particles in it which is supposed to be loose particles in the foam. They are not harmful but can clog the micro-filter. This is supposed to be all that is needed before field use, but I went on.

I filled the bottle again with 20 oz of water. This time I squeezed or pushed down from the top of the bottle to compress before pouring and gradually let go of the squeeze. This allowed the bottle and foam to kind of suck the water in. It worked great and made the filling process much easier. I dispensed out all 20 oz without much effort by turning the bottle upside down and squeezing from the bottle bottom to top. Again I saw quite a bit of grey particles so I ended up repeating this process with my entire bottle of spring water which was five times in total.
residue after 5
Residue after fifth dispense
There was still a grey color with my photo showing the amount of residue left. Well, I'm hoping the micro-filter catches the residue from here on and doesn't clog up.

The alternating squeeze motion of the bottle was easy enough to do. The silicone bottle is extremely flexible but the foam inside is fairly stiff. I can feel two hard portions inside the foam that prevent a full compression when I squeeze from the sides. I can't feel them from the front and back so I'll squeeze in that direction to get a better compression on the foam. The force required was similar to using one of those foam hand exercise balls.

I didn't have enough bottled spring water to fill my sink to simulate a pond situation. I'm interested to see how easy it is to fill the S3 with standing water vs. running water. I expect that squeezing the bottle and sucking the water in will help but I need to try that out.

I'm wondering how well the bottle size will serve for treating water quickly. How long will it take to fill bottles for continuing my hike? Can my husband share the S3 with me or does he need to carry another filter? If we are in an area that requires the S3 purification with concerns of heavy metals or viruses, I suppose that we would have to accept the additional time requirement.

The size and weight of the S3 bottle make it a little bulky for backcountry packing especially since the bottle should be stored in the expanded state. However, the Micro Squeeze Filter would be adequate in most situations. In cases where I would need the extra purification of heavy metals or viruses, I think I would be happy to carry the extra weight and bulk. I probably wouldn't carry the plunger with me for the same reason but plan to use it at home. I would just carry the adapter and backflush using it if needed.


instruction sheetRegular Use Instructions were included but are also printed on the side of the bottle. How convenient is that? Step 1 is to unscrew the Micro Squeeze Filter from the top of the bottle (or just the cap if that is how it was stored) then fill the bottle to the max fill line and screw the filter back on top. Step 2 is to squeeze the bottle in alternating motion for 10 seconds. Step 3 is to dispense the water into another container by squeezing the bottle.

There was also an Initial Usage Instruction sheet which warns that the white cap is the only thing that should be removed. Trying to 'open' the black cap can break the seal and is difficult to reseal.

It also states that the bottle may be damp due to pre-activation during manufacturing. The bottle is okay to store wet and won't develop mold or bacteria or odor.

First use steps are to wash out any loose material so that I don't drink it (not particularly harmful but may taste metallic) and to avoid clogging the Micro Squeeze Filter. To do this, I simply fill the bottle halfway and squeeze ten times then add to the max fill line and squeeze ten more times. Then I force the water out (not through the Squeeze Filter) by rolling the bottle up.

The bottle should be stored fully expanded to maximize lifespan of the foam.


The S3 Select Water Purifier is a two-stage water purification and filtration system which removes bacteria, protozoa, chemicals, pesticides, viruses and heavy metals.

Initial Likes:
Removes Viruses and Heavy Metals
Includes Backflushing Plunger/Adapter
Set includes bottle (purifier) and micro squeeze (filter)

Initial Concerns:
Filling from standing water sources
Smaller volume bottle
Extra weight and bulk



10x squeeze
10x squeeze
drink squeeze
drink squeeze
Over the Field Test period, I used the Sawyer S3 on day hikes, mountain bike rides and one trail run. It allowed me to carry less water in areas where water would be available en route.

Cronan Ranch Trails, California: 5.3 mi (8.5 km); 65 to 70 F (18 to 21 C); 500 to 1,500 ft (150 to 450 m) elevation; water filtered from American River

Lower Gerle Loop in the Auburn Recreation Area, California: 3 mi (5 km); 764 to 921 ft (233 to 281 m) elevation; 45 to 54 F (7 to 12 C); dark stormy day with sun break

Mountain Biking:
Three rides in Magnolia and Cronan Ranch, California: 500 to 1,500 ft (150 to 450 m); 52 to 62 F (11 to 17 C); mostly clear; water from river

Olmstead Loop, Cool, California: 9.8 mi (16 km); 1,022 to 1,686 ft (312 to 514 m) elevation; 50 F (10 C); partly sunny; water at creek crossing

Darrington Trail, Folsom Lake, California: 8.5 mi (14 km); 470 to 613 ft (143 to 187 m) elevation; 62 F (17 C); partly sunny; water at lake


squeeze fill
squeeze to fill
squeeze dispense
squeeze dispense
The first time that I tried to unscrew the micro filter from the top of the S3 bottle, the black ring on the S3 bottle began to unscrew. I was being careful but it took no effort at all for this to happen. If the black ring is supposed to be securely attached to the S3 bottle (as it seems to indicate in the instructions) then it should be glued or welded in place or something. It appeared that there were just normal screw threads with nothing else to hold it in place. I tightened it back down and continued to be careful when unscrewing the filter with no further issues. After this, I wondered if the black lid on the S3 bottle was intact but I never had any issue with water squirting out around the black lid. Even with the squeezing force, the water only exited through the top as intended.

The process for getting water was much easier if I squeezed the bottle and sucked the water in. Even in a flowing stream, the small opening and foam kept the water from easily filling the bottle. When I squeezed it first, it wasn't as simple as filling an empty reservoir, but it worked. The 10 times of squishing back and forth wasn't a big deal in terms of ease on my hands and the time it took was okay. The problem is that the 10x squishing is just half of the process and that it only produced 20 oz (0.6 L) of drinking water. I still had to squeeze out through the microfilter as much water as I could which took some effort.

On the first hike, I drank the first bottle through the filter and then repeated the fill, squish process for a bottle for my husband. I did not dispense the water first into yet another vessel since we were thirsty. That would add another step to the process which I tried later when I needed to carry water. On that hike the filling process was similar with no issue filling if I compressed the foam first and sucked the water in. Again the 10x purifying squishing process was easy enough. This time I squeezed the purified water through the micro filter into a water bottle for carrying on the hike. It flowed easily enough with no real problem. I think that I prefer to just squeeze into another bottle when I collect the water rather than trying to drink with the filter atop the S3 bottle. It's just easier to squeeze into a wide-mouth bottle than into my mouth. And it's much easier to control the amount of water that I want to drink in one sip from my bottle.

The weight and bulk of the S3 Bottle is quite prohibitive if I'm not SURE that there would be heavy metals or pesticides to worry about filtering out. In the case where I am concerned about those impurities, I wouldn't mind carrying the extra weight since I don't know of any other easy way to eliminate them. However, I think if I was only concerned about viruses then I would probably use iodine tablets just as a weight savings over the S3 Bottle.

I discovered that a bottle cap for a typical 20 oz (0.6 L) beverage fits the S3 bottle. This made me happy because I've lost caps before that are a special size but had gotten thrown away by accident since they look just like a disposable bottle cap. Since the white cap isn't always used like when the Micro Squeeze is attached instead, the white cap could easily disappear. Yay to Sawyer for using a standard size!

I realized as I was reviewing my photos and naming them for this report that there is a lot of squeezing that is needed to use this bottle. I squeeze to fill it, squeeze to activate the purifying process, squeeze to dispense or drink the water through the filter. I didn't find the squeezing to be too difficult but there definitely is a lot of it.

I didn't really want to carry the plunger with me on every trip, so I made it a habit to backflush (using the plunger) the Micro Squeeze filter between outings.


The S3 Select Water Purifier is a two-stage water purification and filtration system which removes bacteria, protozoa, chemicals, pesticides, viruses and heavy metals.

Can carry S3 bottle when needed or just the filter
Significant purification ability
S3 bottle cap interchanges with standard disposable bottle cap

Small volume purified at once
Extra weight and bulk
Lots of squeezing

This concludes my Field Report. Check back in a few months to see how this test finishes. Thanks to Sawyer Products and for allowing me to test this product.

This report was created with the Report Writer Version 1. Copyright 2021. All rights reserved.

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Reviews > Water Treatment > Filters > Sawyer S3 Select Water Purifier > Test Report by Nancy Griffith

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