Sawyer Inline Water Filter and Purifier – Field Tests
I bought a Sawyer inline water purifier about a month ago, hoping it would replace my General Ecology First Need water filter which is about 12 ounces heavier. Both the Sawyer and the First Need are the only EPA approved filters on the market capable of filtering giardia, cryptosporidium, and viruses. The Sawyer (model sp125) weighs 2.9 oz. dry and 6.7 oz. when saturated with water. It has an maximum life time of 3000 gallons with regular back flushing and is designed to be compatible with gravity feed bags and hydration systems. The Sawyer uses a fast flow hollow fiber membrane to filter water. When water is drawn though the membrane, it flows through the sidewalls of fibrous tubes that have holes in them and trap any organisms or impurities greater than 2 microns in size.
I field tested the Sawyer with two different hydration systems using Platypus bladders and MSR Nalgene Wide-mouth Canteens. Unfortunately, the Sawyer did not perform well in either configuration, and I've concluded that you can't suck on a hose hard enough to draw water through a 2 micron filter. You need a pump. Period.
In my first field test, I connected the Sawyer filter about 6 inches from a 96 oz. Nalgene bladder which I filled with unpurified water. In this configuration, dirty water flows from the bladder through the inline filter where is it purified. From there, the clean water travels through about 2 feet of plastic tubing to a hydration system bite valve. Both the filter and the bladder are stored in the backpack and the hose is threaded through the backpack's hydration port. In this configuration, I was able to suck some water through the system but only enough to wet my mouth, not slack my thirst. With each draw on the hose, I also swallowed a lot of air and the entire system was marginal. Gravity filtration in this configuration was also very poor and it took about 10 minutes to filter 2 cups of water. That really sucked because I had to do it at night on top of a cold mountain.
In my second field test, I connected the Sawyer filter about 12 inches from a 3L Platypus bladder and attached the inline purifier outside of the backpack onto a shoulder strap of my pack to test the effect of having a very short tube between the clean end of the filter and my mouth. I tried this variation because I thought that placing the suction closer to the filter might improve the flow of water through it.
I filled a 3L platypus bladder with water in my kitchen and attached the Sawyer to the shoulder strap of my pack. It was a little awkward but not bad. I sucked on the tube at home and the flow was much better, so I packed up the car and drove to my local testing ground for a 9 mile hike. About a half mile into the hike, I took a sip and nothing happened. I couldn't pull any water through the filter. I stripped off the pack and checked to see if I had any kinks in the hose. Nope. So I removed the entire system from my pack and held the bladder over my head to check if I could at least get a gravity feed to work. Nothing again. I checked the filter lock, and that wasn't an issue either. So I broke down the entire system, removed the Sawyer, threw it in a mesh pocket, and continued my hike. When I got home, the Sawyer filter went into my big box of unloved, rejected hiking toys.
My conclusion after trying these two different hose configurations is that you need the pressure that can be generated by a pump-action system to push the water through a 2 micron filter if there is any distance between the water source and the bite valve. This is the reason why a filter like the Aquamira Frontier Pro, despite its ecological deficiencies and 3 micron pore size, works with a soda bottle reservoir. But if you use an inline filter with a hose-based hydration system and refuse to change, I'm convinced that you are SOL and need to stick with pump filters given the current state of the art in inline water purification.
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I don’t think the in-line filter is getting a fair shake here. For an in-line, gravity-fed filter to work there must be a column of water above the filter because it is this height that actually provides the force to push the water through the filter. The technique relies on a simple equation from physics and static fluids, p = p0+d*g*L where the pressure at the filter is p, p0 is the pressure at the top of the water column, g is gravity and d is the density of water. The difference in pressure is what produces the force to push the water into the filter. So you can’t have your hose loop around, it must be straight down and they aren’t made for sucking through.
The suggestion of using a pump type filter is irrelevant because as I see it you are trying to make a system that will work while moving but with a pump you will have to stop and manually pump so why not just use a gravity filter like it is intended, hung from a tree or you can even hold it up yourself, if you are going to stop anyways. A pump filter actually runs a little slower than a gravity one, hand pump filters are usually 0.5-1.0 L/min while a gravity filter can filter 1+ L/min. I suspect your tree system was so slow because you didn’t have an air hole in your reservoir. Think about a can of soda, if you turn it upside down it’s very difficult for the liquid to flow out smoothly because it is creating a vacuum behind the fluid, but if you puncture the other side of the can it can “breath.” Every time you got a burst of air in your system it was because the reservoir was trying to equalize the pressure in the bag. Providing an air hole will probably solve the problem but it may still be too difficult to suck through.
I’d agree with you if the Sawyer were marketed as just a gravity filter, but it’s not. It’s intended to be used as an inline filter in a bite and suck hoser system, and for that it fails miserably.
I’ve set up the Sawyer Inline water filter as a gravity fed filter connected directly under a 3L platypus Hoser (2 inches of tubing). I then connected the hose to a platypus collapsible bottle by replacing the bite valve on the 3-1/2 foot tube with a filter link connection to the other bottle. With the dirty water platypus hooked on a tree branch and the clean water bag on the ground I get at least 1L per minute filtration rate. I’m really happy with my 8 oz clean water solution. It really beats pumping. I suspect most of your issue is related to the effect of the bite valve. My filter came with a water bottle basically to use as a straw. No bite valve. Try again without the bite valve. It won’t work as you planned but you may find you pull it out of your unloved toy drawer.
I haven’t tried a gravity setup with a Camelback valve, and I probably should. The MSR bite valve I used is crap. No doubt about that. Of course, I think Platypus now has a gravity system that is even lighter than the Sawyer, but for the sake of completeness, I should try it again and write up the results.
Problem here is that I don’t want a gravity system at all. That was only a last ditch test to see if the Sawyer would work in ANY configuration after failing to work in the configuration that I was told would work – which is a direct bite and suck from a dirty bag through the sawyer and into my mouth. I did test that with a camelback bite valve and it didn’t work. See picture above.
I think you might have a defective unit, or, it may be clogged. I’ve got a Sawyer inline filter and have used it extensively without issue. Sure, there is an increase in required suction, but I’ve found that it isn’t that much more than having no filter at all. Of everyone that has tried it, none have mentioned it was harder to draw fluids, whether they knew the filter was there or not.
Ok and I can find just as many people who’ve shared my experience. Plus, I recently had the same experience with a gravity filter setup using the Aquamira Frontier Pro. I think the bottom line for me is not to trust a gravity system on a multi-day trip. I’ve been burned doing this and it won’t happen again…for a few years, at least. I want a system that works quickly 99.9% of the time, and that’s my First Need Pump Purifier.
My Sawyer Gravity System(Ripstop nylon WaterBag to MSR Dromlite works great). However, the filter is not gaper/flatlander proof. Can’t let it freeze and needs to be primed.
Is your sawyer filter backwards or was it? I own 3 of these filters and have never had an issue running it inline with any brand of hydration system. I liken the force required to drink on par with drinking a milkshake through a straw- not much more than with no filter.
I first must ask you which filter were you using, the inline filter or the inline purifier? It might be very hard to drink in an inline fashion through the sawyer inline purifier. The inline purifier is way overkill for backcountry America use (I’m guessing that’s where you are from your pictures).
The inline microfilter has a pore size of .2 microns absolute, and sawyer’s site says that it’s something on the order of .1 micron. You stated that the filter has a pore size of 2 microns, just be aware that it’s 10 times less than that. Still my previous assertions stand about the drinking force needed. I even use the flow through system for very long days on the mountain bike, and I’m able to sip enough water in a quick enough time while working hard to not be out of breath.
I was using the inline purifier. For areas with clean water free of toxic chemicals and fertizilers, I am willing to use a filter. I prefer using a Frontier Pro in those cases because it is so easy to attach to a used soda bottle or platypus bladder.
I have heard that the Sawyer purifier needs to be primed before it can be used. Priming requires faucet pressure to work. Manually forcing water through the purifier doesnt work. Once it is stored dry it needs to be primed again, meaning it needs to be packed ‘wet’ into the field.
I used a Sawyer inline for my entire Long Trail thru hike last summer with great results. My father used a Steripen and got beaver fever, my buddy used aquamira and always took twice as long to water up as I did, to say nothing of the 30 minutes he always had to wait before drinking. Occasionally the Sawyer would get slow, particularly if I let air into the system, but with careful use it is a really great solution that kept me healthy.
As another commenter mentioned, the filter pore size is 0.2 microns (two-tenths of a micron). 2 microns is too big to filter out viruses, and if you don’t understand that you are probably out of your expertise trying to evaluate a water filter.
Gents – I think we need to be more specific about model numbers here. Sawyer makes a lot of purifiers and filters. They’re not all the same\. That said, pore size is not an absolute indicator of effectiveness. REI doesn’t list pore size on their filter guides for this specifc reason – there’s of marketing bull**it out there. Also, giardia, which is commonly referred to as beaver fever is not a virus.
I didn’t mean to suggest in my post that 0.2 microns will remove viruses any more than 2 micron pores. It won’t. You need iodine or UV light or something like that to kill viruses. But the smaller the holes, the harder it will be to get water through it.
Tom – didn’t think you did. I just super picky on this topic. Must be because I’m a pisces. Purifiers remove viruses, but must be certified by an EPA approved lab to be called a purifier and not a filter. You can also kill them with chlorine dioxide and UV light, but water temperature and turbidity can effect thier effectiveness and required exposure time. Of course, not sterilizing your hands after you treat water can negate everything.
W.H.O. has some papers on water filtration. For example, search katadyn on their page. Regards.