Exploring some simple ways to improve the performance of my favorite lightweight water filter.
The Sawyer Squeeze is my favorite lightweight water filter. I bought one several years ago when I lived in Asheville, NC and used it for day hikes, backcountry fishing and solo backpacking trips. Just about every trip outside saw this little filter in my pack, along with a single lightweight water bottle. The squeeze would fill my water bottle in a few seconds and packed up light enough that there was never a reason to leave it behind.
As much as I love the Squeeze, I’ve always had one gripe with the system. The mylar squeeze bags are difficult to fill. In western North Carolina, most of the water I found was moving, so I could hold the pouch under a rivulet and fill it fairly easily, but when I tried to use the Squeeze a few years ago in the Boundary Waters I found filling the bag very challenging. The mylar pouches simply wouldn’t stay open well enough to fill with water when held under the surface of a lake. After a few failed attempts at swishing the pouch through the water I gave up and treated my water bottle with iodine for the rest of the trip.
A few months ago I was talking water filters with one of my wife’s coworkers and mentioned my gripe about filling Squeeze pouches. Aaron had hiked the AT and used a Squeeze to filter his water on the trail. He had a solution. As it turns out, the threads on a Sawyer Squeeze match those on a Smart Water bottle. The bottles are flexible enough to substitute for the mylar pouches that come with the Squeeze, but rigid enough that they can be filled easily in still or slow moving water. Aaron also mentioned that a 1-Liter Smart Water bottle is the best ultralight water bottle he had found for long distance hiking, and that there is a whole bunch of info to be found on the web about hacking the Squeeze.
I headed home and started digging around the web, and sure enough, there was a lot out there about optimizing this little filter. Many of the articles focused various ways to convert the Squeeze into a gravity filter and eliminate the need to squeeze water through the filter by hand. My curiosity was piqued and I decided that I’d explore a few of these ideas the next time I got a little time free for a DIY project. A couple weeks ago I dug into the project and tried to come up with some of my own hacks for my favorite water filter.
At the end of last summer I picked up a few Smart Water bottles and had been using them as water bottles on day hikes around Madison. I grabbed one of these, filled it with water, screwed it to the Squeeze and went to work. As promised, the bottle easily pushed water through the filter. Unlike the mylar bag, it can’t be rolled up to reduce volume as water is expelled, but I found that it was just as effective to “burp” the bottle halfway through filtering to fill it half way with air. I think the air behind the water actually does a better, faster job of driving water through the filter than the mylar pouches do.
The Smart bottle weighs that same as a 64 ounce Squeeze mylar pouch, which is the one I typically carriy on the trail. This means that the Squeeze and bottle, soaking wet, comes in at only 5 ounces. Given the ease of filling the Smart bottle in still water, the ease of squeezing the bottle and the equal weight I would say that, if you have a Sawyer Squeeze, there is no reason not to run out and spend a couple dollars on a bottle of water and dramatically improve the performance of your water
Playing with Gravity
The Smart Water bottle hack is the perfect solution for filtering water from lakes and slow moving rivers, but what about converting the Squeeze into a gravity filter for hands-free filtering? The filter comes equipped with 1/4″ nipples on both the inflow and outflow ends, so it should be easy to rig the thing up for gravity feed. I made a trip to the local hardware store for 1/4″ inside diameter tubing and got to work.
In my first effort I tried to mate the threads from a Smart Water bottle to a waterproof stuffsack from my gear closet. I cut down the bottle so that only the neck and a small flange remained and cut a matching hole in the center of the bottom of the stuff sack. After fitting the bottle neck through the hole I tightly wrapped the fabric around the bottle with a stout rubber band.
Once secure I replaced the cap on the bottle threads and filled the stuffsack with water to test the seal between plastic and fabric. The result was a complete fail. I had chosen an old stuff sack for the project and the seam tape had failed. Water poured out the seams at the bottom of the stuffsack. There was no way to tell if the joint between bottle neck and fabric was holding water because the whole bag was a sieve.
A couple minutes of rummaging in the gear bin produced a brand new seam taped sil-nylon stuffsack. Rather than cut into this sack right away, I gave it a quick fill test to confirm that it would hold water. The result was disappointing. The pressure of water inside the bag forced drops through the seams despite the seam tape. I briefly considered running out to buy a new bag but then thought better of it. The stuff-sack-gravity-feed would go on the shelf as a possible option for future experiments.
In my next attempt I used a 2-Liter Platypus hydration bladder as the gravity feed reservoir. This bladder is similar to the one that is provided with the Platypus GravityWorks filter system, which is my favorite for group trips and canoe camping. The bladder has a push-button connection that allows you to easily remove the outlet hose from the reservoir. I connected a short length of 1/4″ tubing to the quick release fitting and attached this to the inflow nipple on the grey stopper at the top of the Squeeze filter. For the outflow I used 3 feet of tubing and a plastic squeeze clamp salvaged from my homebrew gear.
The Platypus bladder worked flawlessly with the Squeeze filter. I filled the bladder with 2 liters of water and opened the clamp. My Smart bottle was filled in just over two minutes. Perfect solution.
Unfortunately, the Playpus filter is both heavy and expensive, and this makes it a less than ideal hack for the lightweight Squeeze filter. Filter plus hydration bladder tip the scales at about 9 ounces, which is nearly double the weight of the Squeeze and mylar bag alone. There had to be a lighter solution.
Bottles and Bags
What if I could use a Smart bottle for the reservoir instead of a bladder? That would let me carry only one “dirty side” container for the filter system and use it for both gravity feed and hand squeezing. I taped a piece of accessory cord to the bottom of a bottle and set out to find out if it would work.
I screwed a full bottle of water directly to the top of the filter, hung it from a hook and opened the clamp. Nothing happened. I gave the bottle a squeeze and that started things moving, but the flow rate was extremely slow. The bottle appeared to be too rigid to smoothly collapse as the water flowed through the filter. The same stiffness that made it easier to fill than the mylar pouch was now working against gravity. It took more than 7 minutes to filter a liter of water. Definitely a fail.
If the bottle wouldn’t work as a gravity reservoir, what about one of the mylar pouches? I punched a hole through the edge of one of my Squeeze pouches, filled the pouch with water and set the timer. Like the Platypus bag, the system worked flawlessly, filtering a liter of water in a little over two minutes. What’s better is that the mylar bag weighs less than an ounce. Bag, tubing and clamp together weigh 2 ounces, which means that adding this lightweight gravity kit to the Squeeze and Smart bottle brings the whole rig up to 7 ounces. Not bad considering the versatility you get from adding a gravity feed component.
There was still the problem of filling the pouch, which was my whole reason for digging into this topic in the first place. If the pouches are difficult to fill they don’t really offer a good solution for gravity feed.
The answer was obvious, if I was planning to carry a “dirty side” bottle AND a mylar pouch I could fill the pouch with the bottle. And it would be a lot easier to fill the pouch if I cut the top out of it.
Cutting the top out of the pouch allows it to be rapidly and repeatedly filled from anything from a cook pot to a Smart bottle. This means it can be hung on a branch and used to fill bottles for several people without interruption. This solution ticks all the boxes I was looking for in a gravity feed rig. It’s lightweight at only a couple ounces with hose and clamp, it is affordable since the Squeeze comes with several mylar pouches, it filters water quickly and it’s easy to fill.
After running through these various experiments I’ve come to a few conclusions about the Sawyer Squeeze. First off, adding a Smart Water bottle as a dirty side reservoir is an obvious choice. The bottle is easy to fill, just as light as the mylar bags that come with the Squeeze and just as effective at forcing water through the filter. There’s no reason not to buy one of these bottles to upgrade your filter.
Gravity systems are a bit more complicated. The Smart bottle definitely doesn’t serve as a reservoir for a gravity system, so that option is out. I’m still curious about mating an ultralight sil-nylon stuffsack to the Squeeze, but I’m not excited about the expense of components and not confident that the thing will hold water. The Platypus bladder works great and would be an excellent choice for canoe camping or car camping. Buying a hydration bladder to add to a Sawyer Squeeze is less expensive than buying a standalone gravity filter like the GravityWorks and seems to provide most of the utility of that system. This is a solid option if you want a gravity system that is stout and effective.
In the end, my favorite solution to the gravity filter is simply to cut the bottom out of one of the mylar bags that come with the Squeeze. The pouches are then easily filled from your dirty side bottle and packing a pouch and length of tubing only adds a couple ounces to your water filtration system. It isn’t as elegant a solution as the Platypus bag, but it’s quite a bit lighter and less bulky, which means that I’m more likely to throw it in my pack.
Buy a 1-Liter bottle of Smart Water and use it for your dirty side reservoir on the Sawyer Squeeze. Buy 3 feet of tubing and a plastic clamp. Use one of the Sawyer mylar pouches as a gravity reservoir. Simple, effective, affordable.
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