The Sawyer Mini Filter

Lightweight Water Filtration Revisited

A couple of years ago I posted an article about the lightweight water filtration setup that Sandra D and I were using at the time. Up until recently we’ve been using that same kit, but with the introduction of the SP128 Sawyer Mini filter about a month ago it was clear that the time to make a change had arrived. Here’s a look at the new filter and one way that it can be used to drink directly from a Platypus reservoir.

Some Background on Sawyer Filters

Sawyer has been making lightweight water filters for years. Hikers (among others) have picked up on this and many of us have abandoned the days of using chemicals or having to pump for their water. Instead, gravity can be used (as in our previous setup), or squeezing the reservoir to force water through the filter (as in the Sawyer Squeeze setup), or simply drinking directly through the filter (which is what you’ll see below). Generally, these are simple techniques which produce great tasting water via compact filters that weigh very little.

Prior to the SP128 (“Mini”), the SP131 (“Squeeze”) was somewhat popular over the SP122 (“3-Way”) kit, which already boasted “ultralight” right on the packaging. As you might have guessed each generation has become smaller and lighter. All of these filters are 0.1 micron absolute rating, which is more than adequate for filtering from water sources in the US. For worldwide use these are adequate filters for developed countries. For under developed countries where viral contamination of drinking water can occur, these are not suitable filters. Although viral water filters are available, boiling and chemical treatment are better options. So, yeah, getting back on topic… great filters to take while recreating in the developed world.

Bloggers have been talking a lot about the new Sawyer Mini filter. John Abela of HikeLighter.com covers everything you ever wanted to know about it and then some in his comprehensive post, which I would suggest checking out for a different perspective.

I’m not going to say a whole lot about the filter. It’s light, small, inexpensive, and easy/flexible to use… it’s a water filter. If you’re shopping the options, stop now and just buy one.

The Purchased Bits

This is easy. You’ll need a Platypus Hoser 2L hydration reservoir (about $20), and the SP128 Sawyer Mini filter (about $25). By the time you are done putting this together you’ll have a water filter and hydration reservoir that weighs less than 5 ounces and cost less than $50. If you don’t like this particular setup I’ll talk about a couple other ways the filter can be used before wrapping up.

Sawyer SP128 Mini Filter
Sawyer SP128 Mini Filter
The Platypus Hoser
The Platypus Hoser

Putting it Together

There’s not much to do. Cut the drink tube a few inches up from the end that connects to the Platypus. Now attach that end to the nipple on the filter that is opposite the arrow showing direction of flow. Attach the other end of the drink tube to the nipple on the filter that the arrow points to. The arrow should be pointing towards the bite valve when put together correctly.

Platy and Mini Happily Married
Platy and Mini Happily Married

If you try this, you’ll notice it’s a very tight fit. This is good. We don’t want those tubes pulling loose inside your backpack. To get them pushed all the way onto the filter, run some hot water over the ends of the drink tube to soften it up a bit, then muscle them all the way on. When you’re all done, they’re not going to want to come back off (so getting it apart is possible but not easy… just bear that in mind).

Differences From Our Previous Setup

Previously our filtration setup was designed to be shared between two or more people. It worked fine for one, but seemed like a lot to carry, even as light as it was. Simplifying and lightening up were part of the reason for change. The other part is that Sandra D and I have been moving towards self sufficient setups rather than sharing gear. I realize that may seem odd for a married couple who hikes together; I’ll explain why I think it makes sense in another post that I’m working on. The Mini is the right size and price to make this an easy decision for us.

SP128 Mini compared to SP122 3-Way
SP128 Mini compared to SP122 3-Way

This setup has less pieces and trimmed about 8 ounces (as carried by one person) which is very good. The external dirty water reservoir is now gone, as is the dirty water tube. The quick couplings are gone too, though they could make a future re-appearance in this system. I’ll wait until that happens to elaborate. What you really want to know is: what about drinking through the filter?? It’s not bad! The extra effort required is minimal and I acclimated to it quickly. Back flushing after trips seems to be the key to maintaining flow that doesn’t require sucking the chrome off a trailer hitch… err, ok. I’m actually back flushing through the bite valve, which works just fine and hasn’t impacted my bite valve at all.

Getting water into the Platypus is done by pouring from a cup, mug, bowl, or even a freezer bag which works well as a scoop in shallow areas.

The Cons

It’s hard to come up with any cons. I mentioned in our original filtration post that membrane filters need to be protected from freezing (all of them, not just Sawyer filters) so that isn’t a specific negative, but it’s something to be aware of. There are ways to test the integrity of a membrane filter but it’s not something that can be done on the trail, and even at home nobody but really geeky people will have the goods sitting around to do it. Just don’t let it freeze and be confident that it will serve you for 100,000 gallons worth of filtered water.

Other Ways to use the Sawyer Mini Filter

  • Gravity: Temporarily remove the bite valve and hang it from a tree. It’s about as fast as the Sawyer 3-Way in gravity mode, if not faster.
  • Squeeze: The Mini filter comes with a squeeze bag. The filter itself has a female thread on the dirty side that can be attached to the squeeze bag directly.
  • Survival Straw: Yes, the filter comes with a straw also and it can be used to drink directly from a lake, river, puddle, bottle of water, or your GF’s bellly button.
  • Another Way with Platypus: Using the thread on the filter, it can be threaded onto a Platypus bladder without cutting the tube. However this would be a bit awkward in the hydration sleeve of a backpack. Also worth noting, it seems that the thread on the filter only matches well with some Platypus bladders and is leaking with others. Not so good.
Mini and Included Accessories
Mini and Included Accessories

The Bottom Line

This post was way longer than it needed to be. If you need a water filter for backpacking and prefer not to pump, stir, or use chemicals it will be hard to do better than the Sawyer Mini.

Jacob D Written by:

Jacob is the head honcho, wearer of many hats, and modern day berserker here at Hike It. Like It. When he’s not out hiking or running the trails you’ll find him operating in full capacity as a Super Dad and chipping away at a degree in Kinesiology. This guy likes to stay busy.
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20 Comments

  1. […] an aluminum non-stick pan so I could make some bread and warm up tortillas Water Filtration: Sawyer Mini Filter with squeeze bag Hydration: 2x 1 Liter bottles Trekking Poles: Cascade Mountain Tech Flick Locks […]

  2. Andy Jarman
    March 1, 2015
    Reply

    Carry a tornado tube (https://www.youtube.com/watch?v=-JD736W9zBE ), screw this onto your filter’s output end, then screw a bottle of clean water onto the other end of the tornado tube – then squeeze.

    I wrote to Sawyer and asked them why they didn’t have a threaded outlet to allow users to back flush by squeezing their clean water back through the filter like this.

    Their concern was that uninitiated might use the filter back to front and contaminate both sides of the filter.

    I use a hydrogen peroxide based solution (AO Sept) for cleaning my contact lenses, this is also excellent for disinfecting infected wounds AND can be added to your sawyer backwash at the end of the trip – thereby preventing bacteria build up in the filter in preparation for storage.

  3. David
    October 25, 2014
    Reply

    I have the Mini, but have concerns about longevity in the field. Do you think the old 3-way inline filter would be faster in gravity mode? I plan to use gravity filtration exclusively. The SP121(?) seems to be about 1 oz heavier than the Mini. Have you used the Mini on extended trips and if so, did the flow rate slow down? If you are carrying the syringe to backflush it seems you might as well bring the heavier filter to begin with, since the syringe adds back the 1 oz difference in weight.

    • October 27, 2014
      Reply

      Hi David. Good questions and good points raised.

      I have both the old 3-Way and the new Mini Sawyer filters. You’re right about the 3-way being a faster gravity filter. If you plan to exclusively gravity filter I would probably suggest the 3-way. It also seems to become obstructed less easily, probably due to it having more surface area (just a guess). I don’t really get out on “extended” trips very often and I don’t know exactly what your definition of that would be, but if you’re thinking something like 2 weeks or longer then I think I’d bring the syringe regardless of which filter you own.

      It’s worth noting that I have been trying various ways of flushing my Mini filter and have not been very satisfied. The syringe packaged with it doesn’t make a good seal against the filter itself nor the tubing that you might use along with it. After flushing directly through the bite valve a few times, the valve became leaky. Probably my fault for abusing it like that. I’ve since stopped flushing that way and have been trying various syringe tips that can fit more snugly inside the tube but haven’t got an ideal solution just yet. What I’m doing now works well enough until I find a better way.

      I really need to do an update to this post as I have since stopped drinking directly through the mini and have gone back to using it in squeeze mode. Once it becomes slightly obstructed it’s difficult to get flow through it (via sucking on a tube). Overall I still think the Mini is a nice little filter and a good value for a squeeze filter. If you can keep it clean it works decently as a gravity filter too.

      • Andrew W
        December 24, 2014
        Reply

        I have used the mini on a few mid length trips (2 wks) and I use it exclusively as a gravity filter. I can filter 2L in about 5 min. I do bring my syringe along to backflush it after each use. This might be excessive but from my experience the filter slows down after a few liters.

        • December 26, 2014
          Reply

          Thanks for the additional feedback Andrew. After using the Sawyer mini all year I would agree with you that backflushing after each use is a good idea and NOT excessive if you want to maintain good flow. Unfortunately this filter does seem to become obstructed fairly easily. I still think it can be a good choice for a gravity filter if maintained, however the 3-way is probably more practical and I would expect the 3-way to maintain good flow after years of use.

  4. Drew
    June 26, 2014
    Reply

    Hey there,

    I was wondering if you know which Platypus bladders are directly compatible with the Mini Squeeze? I would like to be able to use a Big Zip bladder (as water collection is much more convenient with the big opening) for dirty water and thread the filter directly onto the bladder. I understand that this works with the Hoser but I suspect that the Big Zip has a different thread. I’ve asked Sawyer directly but they weren’t helpful.

    Thanks

    • October 22, 2014
      Reply

      Drew,

      Sorry about the late reply, somehow I missed your question. I don’t own a Big Zip but I can tell you that it does not have a thread at all. As you mentioned, the threaded cap is replaced by the “zipper” style opening. As far as the rest of them go, the Mini should be able to thread directly onto the bladder.

  5. June 23, 2014
    Reply

    I have a question about backflow cleaning of the filter with it installed inline like that. The question being: how do you do it? It seems like having a length of hose attached to the output end of the filter would decrease the force with which the water is pumped back via the syringe (or other method of backflow), thus decreasing the effectiveness of the cleaning. Any tips or advice would be greatly appreciated!

    • June 24, 2014
      Reply

      Whoops I see you’re backflushing through the bite valve!

      • June 25, 2014
        Reply

        Hi Maia. I’ve actually stopped flushing through the bite valve after one started leaking. I just pull it off and flush through the tube. That short length of tube doesn’t cause any significant loss of pressure or flow. If for some reason it was necessary, it wouldn’t be too difficult to pull the drink tube off and flush into directly.

  6. October 23, 2013
    Reply

    I’ve used Aqua Mira drops for years carried in a two Visine one ounce containers and it’s worked well. I just want to understand why you choose a filter?

    • October 23, 2013
      Reply

      Hi! Nothing wrong with Chlorine Dioxide as far as I’m concerned. In fact, I carry a few tablets as a backup. In the long run the filter is more economical assuming it doesn’t get smashed or left to freeze. Aside from that, there’s less fiddle factor with the filter. No measuring, no mixing, no wait time (which should vary depending on the conditions of the water source). I think these are fairly minor nits, but they’re mostly the reasons why I choose a filter.

      • October 23, 2013
        Reply

        Good points. I always like to hear the reasons why people choose the gear they do and I appreciate when they have thought it thru’.

        I guess I don’t want to worry about something breaking. On a JMT trip years ago, the membrane on my filter (and it’s back-up) both failed in one day. I was left boiling water for the remainder of the trail. The drops do have a setup time, but I haven’t found that to be an impediment.

        Love your blog BTW! Check mine out.

        • October 23, 2013
          Reply

          Gear breakdown is usually in my planning without going too nuts and packing all the “what if’s”. That’s what I carry the Aqua Mira too. It’s small and light so I give myself a pass on that one 🙂 Gear redundancy is also part of the reason why my wife and I are switching to self sufficient set ups, that’s another story though.

          I checked out your blog… very nice! Lots of good trip reports. I just finished watching your Quinzhee video (cool) and reading another of your snowshoe reports. I smiled at your buddy’s Tyvek Homewrap tarp. It’s not hard to spot us UL types most of the time! I’ve learned a few lessons about going UL in the snow though and have made some adjustments to my kit.

  7. October 23, 2013
    Reply

    Thanks for the review, I have been happy with my Sawyer filter (squeeze) except that the squeeze bag developed a pinsize hole after only a few days of use. I think I will look into using it as a gravity or inline filter like you have done. Or maybe I will repurpose a platypus to use as the squeeze bag.

    • October 23, 2013
      Reply

      Hey Adam. I’ve heard lots of woes about the original Sawyer squeeze bag having some problems. This newer bag is reportedly more durable, but I’m not a squeezer (of filters anyway!) so I can’t comment with certainty. I have hiked with at least one person who used their squeeze filter inline as I have shown here.

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