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Reviews > Water Treatment > Filters > Sawyer One-Gallon Gravity System > Test Report by Richard Lyon

Test Report by Richard Lyon

Initial Report October 9, 2021
Field Report December 31, 2021
Long Term Report expected February/March 2022


Male, 75 years old  
Height: 6' 3" [1.91 m]
Weight: 205 lb [(91 kg])
Email address: Montana DOT angler AT gmail DOT com
Home: Outside Bozeman, Montana USA, in the Bridger Mountains

I've been backpacking for half a century, most often in the Rockies. I do at least one weeklong trip every summer, and often take three-day trips.  I'm usually camping in alpine terrain, at altitudes 5000 to 10000 ft [1500 - 3000 m].  I prefer base camp backpacking, a long hike in with day trips from camp.  Though always looking for ways to reduce my pack weight, I still tend to include my favorite camp conveniences. I always sleep in a floored tent and like hot meals. Backcountry trips are often planned around skiing or ski touring in the winter or fishing opportunities in warmer weather.

INITIAL REPORT - October 9, 2021

The Product

Sawyer 1
Sawyer offers its one-gallon gravity filtration System in two configurations. I shall be testing the Sawyer 1-Gallon Gravity System (SP160), which has five principal components: starting from the left in the photo, one gallon [3.78 liter] plastic water bladder, gravity hose [pictured with fittings on both ends], mini filter, cleaning plunger, and cleaning coupling. With this System I'll supply the vessels for filtered water. The Sawyer 1-Gallon Dual Bladder Gravity System (SP2160) comes with two bladders, one for "dirty" [unfiltered] water and the second for the "clean" [filtered] end product, and several additional components to facilitate water flow.

Manufacturer: Sawyer
Website: [Note: Sawyer products are not offered for sale on the website. Sawyer will direct a user to online and brick-and-mortar stores where the products may be purchased.]
Filter material: 0.1 Micron Absolute Hollow Fiber Membrane
Capacity, listed: "up to 100,000 gallons" [378,000 liters] [Using either measurement, plenty or water!]
Filter Weight, listed: 1.22 lb [550 g]
Height, listed: 12.6 in [32 cm]
Dimensions, listed: 7.25 x 2.75 in [18 x 7 cm]
Component weights, measured: bladder 3.75 oz [106 g]; gravity hose with fittings 1.25 oz [35 g]; mini filter 1.38 oz [39 g]; cleaning plunger 0.75 oz [106 g]; cleaning coupler [0.1 oz [3 g]; bladder cap 0.25 oz [7 g]; arm 0.12 oz [3 g]; spare O-ring 0.25 oz [7 g] total 7.85 oz [296 g]
Dimensions, measured: hose 26.5 in [67 cm] long; bladder 12 x 14 in [30 x 36 cm], filter with cap 5.2 in [13 cm] long
MSRP: Not available

I cannot explain the discrepancies between listed and measured items above, of which the filter weight is the most puzzling.

How It Works.

Sawyer 2A MINI, an in-line filter that Sawyer also sells as a standalone product, does the work of removing bacteria [99.99999%] and protozoa [99.9999%] from untreated water. Assembly and use are easy - fill the bladder with water, attach the gravity hose to the outlet to the bladder and the MINI, and let gravity do the work. No pumping necessary. The bladder may be hung using its handle or laid on a flat surface. Note that the plastic fittings on the ends of the hose may be removed.

Included accessories can facilitate filtration. By screwing the push-pull white cap on the MINI outlet, as shown in all photos in this Initial Report, I can easily turn the water flow on or off - useful if changing bottles for the filtered water or just for storage A simple screw-on cap for the outlet on the bladder [third from right in photo above] allows carrying water from source to camp without dripping or losing water, or for in-camp storage. The System also includes a plastic arm that clips on to the bladder outlet [second from right] to reduce the risk of crimping, and a replacement O-ring for the MINI [on the right].

The handle on the water bladder makes carrying a full gallon from stream to camp very easy. The handle also makes a more reliable hook for hanging than the small loops or rope handle I have found on other gravity filters. Another simple yet functional design feature is printing on the water bladder directions for backflushing the MINI. That's easy too - screw the coupling on the clean-water end of the MINI, fill the syringe with clean water, fit to the coupling, and press to force the water back through the filter. Sawyer recommends several doses, until the water comes out of the inlet valve clean. Sawyer also recommends frequent backflushing, a practice I heartily endorse based upon problems caused by my neglect in the past.

Trying It Out

I ran two gallons through the System, using tap water, and everything worked as advertised. For the first gallon I hung the bladder from a peg on the wall, into a three-liter water bladder and then a one-liter Nalgene. For the second gallon I laid the bladder flat on a step, draining the water into the same vessels.

Initial Likes

Wide mouth on the water bladder. Should make it easier to fill in the backcountry.
The handle. Makes carrying easy.
The MINI outlet cap. Easier to operate and more reliable than an in-line clamp.
Light weight

Initial Dislikes

No instructions included with the product or on the website. And setup was not entirely intuitive; some trials and errors were needed.
No storage bag included. Easily fixed with a two-gallon Ziploc bag for everything but the bladder, which folds up easily.
The bladder outlet is on the corner, not vertical. It takes some tipping to get the last bit of water through.

FIELD REPORT - December 31, 2021

Field Conditions

Circumstances - a gimpy knee and an on-a-whim ten-day trip to Italy - limited my use of the Sawyer System to a few overnight car camping trips to fishing holes here in Montana. I won't disclose exact locations, as one or two may have been in spots in which overnight camping was prohibited, but all were at established fishing access points here in the Treasure State. Temperatures ranged from as high as 75 F [23 C] during the day to near-freezing or slightly below at night. No precipitation and no other noteworthy meteorological conditions. I drew water from big rivers - clear and clean to the naked eye, from watercourses lined with ranches full of cows, bison, sheep, or other domestic animals, not to mention the wild critters. Nothing I'd drink straight-up except in an emergency.


Like other gravity filters I've owned, operation is easy. Set it up as described in my Initial Report and let gravity do its work. I've had a few issues to deal with, all of which I've handled fairly easily and all of which I believe will diminish after more practice. I will say that the wide mouth on the dirty water bladder makes it reasonably easy to fill it from moving water. I prefer the screw-on cap to the slider system used on other gallon bladders. Takes a bit longer to fill, but is much easier to open and close and reduces the risk of drip.

First two such issues are consequences of having to provide my own container for the filtered water. Unless that vessel is one gallon or larger, I can't walk away and let it drip unless I don't mind wasteful overflow. Often in the past I've filled gravity filters just before bedtime and awakened to a slug of potable water sufficient to accommodate breakfast and my next morning's hiking. I intend to address this matter by purchasing a second one-gallon bladder, probably from Sawyer in order to ensure that I can screw it into the Sawyer MINI. [Note that the Dual Bladder system includes the second container.] Until now I've had to mind the flow into successive one-liter containers. In this process the Outlet cap on the Mini comes in really handy. Simply screw it closed and there's no drip until the clean water container is replaced - and no splash and loss of water when an in-line clamp slips, loosens, or falls off.

The second problem is being sure that the Mini is well inside the clean water container; otherwise I risk a wind that blows the hose and filter aside. Avoiding this mini-disaster [pun intended] means finding a spot to hang the dirty water bag that allows a deep drop. Not a problem when car camping as the door handle of my car works well. When hiking I can usually find a rock of appropriate height to work, though the less-than-vertical drop, exacerbated by the corner nozzle, requires holding the bladder upright to extract the last bit of filtered water.

Even though field filtration has not included "dirty" water with algae or other debris I have backflushed the Mini after every trip, using the process I described in my Initial Report. As the flushed water came out clean after the first flush, that finished the operation.

I haven't used the filter enough to give a reliable report on durability. I can say that there's not much that can go wrong as long as I heed the simple preventive measures noted above. If the stated capacity of 100,000 gallons [>350,000 liters] be accurate, I'm unlikely to need a replacement anytime soon. And should I break something most parts - including the Mini and water bladder, which I consider the most likely to suffer injury - are available individually.


My Field Report ends here, with thanks to Sawyer and for the opportunity to test this product.

I'll post my Long Term Report in a couple of months. Check back then, won't you, for the results of winter testing.


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Reviews > Water Treatment > Filters > Sawyer One-Gallon Gravity System > Test Report by Richard Lyon

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