We took the Sawyer S2 Foam Filter with us on a two-week trip to Mexico, where we knew the tap water was not recommended to drink. The S2 squeezed the heck out of many liters of water and kept us healthy throughout. It is not the easiest or quickest model to use, but the fact that it is effective against viruses and other microorganisms is very comforting, and it was a no-brainer to throw in our luggage. We could bring it along with us on our daily excursions to drink from, and use it in our AirBnB to filter water into other vessels. We did notice some particles from the foam filter in our water that changed our water to a blueish color and were a bit disconcerting to drink.
Sawyer S2 Foam Review
Compare prices at 3 resellers Pros: Effective against viruses, easy to use, inexpensive
Cons: Foam particulate in our water
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Our Analysis and Test Results
The Sawyer S2 is handy to have along with you on your international travels. It protects you from viruses but does deposit debris from the foam into your drinking water.
Our favorite thing about the Sawyer S2 is that it treats everything you're afraid of - including viruses, which not every model in this review does. The Guardian purifies for viruses as well and is faster and more efficient than the S2 but is also considerably more expensive. Our main concern in this area is that when you twist and squeeze the silicone bottle the seal around the top breaks and some un-treated water leaks out and can get into your clean water bottle, contaminating it. This is a bit of a concern, and we needed to pay attention to not twisting it too hard near the seal. Other effective purifications against viruses in this review are chemical treatments like the MSR Aquatabs and Aquamira which do not filter out particulate.
We like that the S2 uses the traditional Sawyer Micro Filter for particulate along with the foam, but were surprised that some of the foam particulates continue to get in our water after about 80 uses. The amount of particulate has lessened, but the tint to our water is still a blueish purple which is a bit of a turn-off.
Ease of Use
The S2 is relatively straight-forward to use, but you need to have some squeeze strength and patience if you're trying to fill up a lot of water bottles. We think the Sawyer Mini is still easier to use as long as the filter unit is unclogged. The first few uses take a while to fill up the bottle as the foam is water repellent until it gets saturated. Then once it is wet, it is much quicker to fill up the bottle. We imagine that this bottle would be challenging to fill up at a shallow water source and don't think it's an excellent choice for using on wilderness trips for that reason. The flexible bottle is ideal for different sized sinks; it can be crushed into a smaller space for filling up. The Guardian is one of the most straightforward filters to use in this test, along with the gravity units like the Platypus GravityWorks.
The S2 is not particularly light, weighing in at 13 ounces and is usually heavier than that since the foam never entirely dries out. However, it is a bottle to hold water in as well as a filter, so it could reduce your weight if you leave another bottle at home. It seems a bit weird that the foam never dries out, but Sawyer assures the user that "the proprietary ingredients in the foam will make sure that your foam does not grow bacteria or develop an odor." The lightest filter that treats for viruses are the chemical treatments like Aquamira. The Sawyer Mini is a great lightweight backpacking choice if you're in an area that you don't need to worry about viruses in your water (anywhere in the US and Canada).
If you have a lot of water to fill, you'll need to dedicate some time out of your day to do it with the S2. The bottle is supposed to treat 20oz but it's hard to get all that water squeezed from the foam, and if you do, you're sure to get foam particulate in your water.
It has 800 uses or about 500 liters worth of water treatment - we imagine the bottle and/or seal around the lid will give out before this amount of uses. If you don't need to worry about viruses, the MSR Gravity treats up to 1500 liters in its lifetime. The Guardian treats all things including viruses and is suitable for 10,000 liters!
If you drink from the filter directly, you can get water almost instantly out of the filter unit. In theory, you can drink right from the bottle, but the long filter and having to really squeeze the bottle make it pretty awkward to do so.
It's easier to squeeze the water out into another vessel. In our timed tests, we managed to squeeze a liter's worth of water in about 2 minutes and 28 seconds. This process can feel tedious if you're filtering a day's worth of water for two people. The fastest product we tested was the Katadyn Gravity Camp at 40 seconds per liter, followed closely by the MSR Guardian at 42 seconds.
We think the S2 is a great product for international travel when you're not sure the water is safe to drink. For backpacking uses, we prefer lighter methods that can treat larger volumes of water at a time like the AutoFlow.
Retailing for $80 the Sawyer S2 is a decent value for what it is. It treats for viruses, which many products in this review do not, so if you need something that is convenient, not super bulky, and a decent value, the S2 could be it, especially if you plan only to use it in a frontcountry setting. The Guardian retails for a whopping $350, so it is a much cheaper alternative to that purifier.
The S2 does it all relatively well. If you're looking for a purifier to treat your water while overseas in a frontcountry setting this product could be for you. It's relatively easy to use and effective. It's not a great choice for backpacking trips and is unnecessary in the US or Canada.
— Jessica Haist