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Reviews > Water Treatment > Filters > Sawyer One-Gallon Gravity System > Test Report by Christie KimberSawyer One-Gallon Gravity System
October 28, 2021
Name: Christie Kimber
Height: 6’0" (183 cm)
Weight: 138 lb (63 kg)
Email address: christiekimber AT yahoo DOT com
City, Province, Country: Campbell River, British Columbia (BC), Canada
I started hiking in 2015 when I moved from Saskatchewan to Vancouver Island, British Columbia. I started with day hikes and have eventually pushed myself to weekend and even week-long excursions. I am a three-season hiker. That being said, as I gather new gear and develop skills I am pushing my limits to try out 4-season backpacking and mountaineering. Vancouver Island gets a lot of rain and has a moderate climate. I also spend time in interior British Columbia in the Rocky Mountains.
Manufacturer: Sawyer Products, Inc.
Year of manufacture: 2021
MSRP: not listed
Listed weight (all contents): 8 oz (227 g)
Actual weight: 8.2 oz (232 g)
Listed weight (filter only): 1.5 oz (43 g)
Actual weight (filter only): 1.6 oz (45 g)
Listed measurements (exactly what is being measured is not specified):
The Sawyer One-Gallon Gravity System (referred to from here on out as "Gravity System") is a portable water filtration system. It's primary use is to provide clean drinking water in the backcountry when a person does not have access to clean water. The water source is suggested to be from natural, freshwater sources. This could include areas such as lakes, rivers, and creeks. Included in the package is a one-gallon (3.78 liter) water bladder, mini filter, cleaning plunger, cleaning coupling, and gravity hose. These items are listed on the side of the original packaging. Once I opened up the package I also noted there were two caps, one for each opening on the water bladder. There was also a port that connected the bottom of the bladder to the tubing and then to the filter. Lastly, there was a black piece of plastic that was not labeled, but from looking at the pictures on the packaging it appears to be some type of hook or handle. Perhaps it could be used to keep the water bladder from sliding around while in use.
The water bladder has a wide mouth on the superior side of it where water would be filled. This is just over 2.25 inches (5.7 cm) in size. The exit port is only 1 inch (2.5 cm) in size. Both ends have screw on caps. The water bladder is made of a flexible plastic material with harder plastic reinforcing both openings, as well as an incorporated handle.
The features of this system include a 0.1-micron absolute hollow fiber membrane filter which is said to remove 100% of microplastics, 99.99999% of bacteria and 99.9999% of protozoa and cysts. This one filter can be used to filter 100, 000 gallons (378547 liters) of water. The total system is lightweight at only 8 oz (227 g), while the filter itself is only 1.5 oz. (43 g). A stated new feature with this current product is the inclusion of a dual threaded mini filter. This allows for the push pull cap to be screwed on for quick on/off functioning during filtering, according to the included packaging. It is also supposed to allow for backwashing as it is compatible with the cleaning coupling.
All Sawyer filters are tested three times according to the manufacturer and no batch testing is done.
The entire one-gallon (3.78 L) of water can be filtered with gravity alone in 7 minutes. No pumping or manual pressure is required.
There is a second version of this water filter available on the website that comes with two plastic bags, one for dirty water and one for clean water.
The Gravity System arrived in new condition. It arrived in a cardboard box, which I appreciated as most of the packaging can be recycled. The filter, plunger, coupling, and hose were in a small plastic bag, although I can appreciate a plastic wrap around a filter for transport to ensure cleanliness.
The one-gallon (3.78 L) bag initially struck me as being very large. I usually carry 1.5 to 2L (0.4 to 0.5 gallon) of water with me at any given time, so the one-gallon (3.78 L) system has about twice as much capacity as I would usually use.
The quality and construction of the water bladder and filter looked excellent. I had no concerns on initial inspection. The fibers of the filter are completely covered.
Unfortunately, no specific instructions on how to assemble and use the Gravity System were included in the package. On the back of the box it does show an undetailed picture of assembly. It also states the product can be used hanging or on a flat surface. In addition, there are care instruction printed directly on the water bladder for cleaning the bladder as well as the filter.
Although it was easy enough to figure out with a couple of minutes of trial and error, I do think a step-by-step guide would be useful for the product. There are enough included parts, including ports and coupling, that it was a bit confusing to assemble for the first time. I did watch a video to ensure I was setting it up correctly prior to trying it out with actual water. I have never used a Sawyer product, and it may be surprising, but I have actually never used a filtration system for my water. I have always used water cleaning tabs as I don't mind the taste and find them quick and easy. I have always wanted to try a filtration system, so I am excited for the opportunity. However, as a total newbie, a step-by-step guide would have been much appreciated.
One other included feature I would have liked is a small bag to store the loose components all together. I will be storing them in my own provided bag, but I think this could be included.
January 3, 2022
Alternatively, for backcountry overnight trips, as well as for large groups, I think this set up is an excellent choice. On these trips I routinely need to filter water. Being able to filter one gallon at a time means I could clean water for multiple people or multiple uses (drinking and cooking water) at once.
When it came to actually using the filter, I did find this relatively easy once I got the hang of it. As I mentioned above, it did take some time to figure out, and I think explicit instructions would have been helpful. I am glad I did not wait to figure out how to use it when I was already in the backcountry and without cell service or I would not have felt confident. However, now that I have it down I have not had any problems.
To use in short:
The wide mouth of the reservoir bag made it easy to fill. The bag also has a stiff handle which contributes to easy filling as well as easy handling once full. The caps and attachments all screw off and on easily. I did not have any difficulty attaching or detaching the tubing. I hung the bag on a tree and held it. So far I have not required the use of included small black handle. I have used a variety of secondary reservoirs to drain the water into including into a cup, pot, water bottle, and water bladder. It is easy to stop filtration midstream by capping the filter or using the in-line clamps if I needed less than one gallon of water.
In terms of flow rate, initially I got about 500 ml (16.9 oz) per one minute with gravity alone. This was slightly increased if I added a bit of pressure to the bag. My first few uses with this filter were with water that was already very clean and clear. I back flushed the filter after each use to clean it according to the instructions on the reservoir bag. After about three uses the flow rate did decrease a bit. So far, I have not had to clean any "dirty" water, which I think is helping with the back flushing and flow rate overall. I will keep an eye on this. I have also not had to clean to reservoir bag beyond rinsing it with clean water when I got home.
The taste of the water has been excellent so far, although I haven't really been putting this to the test as living in a rain forest during the fall and winter means we have access to plenty of clean, clear, fast flowing water.
Overall, I would recommend this product. I think it functions as advertised. I would not use it for day hikes, but I think for backcountry groups the size of packing the large reservoir bag and all of the required components is worth it. It is a space, not weight issue. I could also see rigging up a system where I just brought the filter and some tubing and tried to leave the bag itself at home.
February 22, 2022
During my last day hike in Kimberley, I brought the filter however I did not end up using it. It was quite cold at -13 C ( F) and I was worried about the filter freezing in my bag after use. I didn't think it was worth it at that point and must not have been thirsty enough! I have used it down to -5C (F) with no problems.
I have continued to flush the water system after each use. I did another timed test and the flow rate is now approximately 450 ml per one minute with gravity alone. This is decreased from 500 ml during my first timed test. I think this is quite reasonable, and if the filtration time remains at this rate for the duration of the filter life I will be very satisfied. I have not had any trouble back flushing the system. As my test period has been exclusively in the fall and winter months in British Columbia, the water sources I have used have been very clean and fast flowing at a baseline, so I am unable to report on how larger particulate may affect the filter.
Luckily, I have not managed to lose any parts of the system at this point. That is one concern I have had as there are several loose parts. Whenever I use it I make sure to dismantle and put it all away back into a carry bag.
The bag, connecting tubing, ports, and filter all have very little signs of wear. There are no holes or obvious breakdown points. The water bag specifically is surprisingly robust. It has also been easy to clean the reservoir bag with the wide mouth opening.
This was my first experience using any type of filtration or cleaning system for water in the backcountry. As mentioned, I was previously using chloride tabs. I really liked the taste of the water with this system, as I do find I can taste chemical treatment. However, I will reiterate my previous opinion; for this particular system, I think it is a bit too big and does not pack down well for day hikes. However, for group and multi-day trips it will definitely be coming with me! Overall, I would recommend this product to others.
This concludes my Long-Term Report. Thanks to Sawyer and BackpackGearTest.org for the opportunity to test this product.
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Reviews > Water Treatment > Filters > Sawyer One-Gallon Gravity System > Test Report by Christie Kimber