Water Filter systems, Sawyer Mini questions....

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Koda
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Water Filter systems, Sawyer Mini questions....

Post by Koda » February 7th, 2014, 4:41 pm

I'm shopping for a new water filter system, the new gravity/squeeze filters seem like a major jump in technology over the old pump systems. I'm about the pull the trigger on a new Sawyer Mini...

This will be a change in my hydration procedure so I have a few questions. I think I have a pretty good idea how the Sawyer works: fill up your reservoir with untreated water and place the mini in-line and drink by sucking as usual. Seems pretty simple.

1> did I get that correct? How well does that work? (ok, thats really 2 questions...)
2>can I also squeeze the reservoir to quickly fill a different container?
3>Will the tubes work with Platypus reservoirs? (already invested in Platypus...)
4>are there other filter systems/options worth investing?
5>I'm not smart enough to know... is the Sawyer a purifier as well as a filter and what does that mean?
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Lumpy
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Re: Water Filter systems, Sawyer Mini questions....

Post by Lumpy » February 7th, 2014, 8:10 pm

In order of what I think is important to cover.

The Sawyer Mini is *not* a purifier. A water purifier makes water perfectly safe to drink, in that it removes solids, bacteria, *and* viruses. Bacteria are relatively large, and it doesn't take much of a filter to stop them. Viruses are pretty darn small, and you gotta have a pretty good filter to filter them out. The Sawyer Mini advertises it filters out anything bigger than 0.1 micron. There is a .02 micron Sawyer filter, which is advertised to also filter out viruses, but it is larger than the mini, heck it's even larger than the 0.1 non-mini filter. Luckily, here in America and Canada, you don't have to be very concerned about viruses in water sources. No, really, you don't. However, if you are, carry some Aqua Mira with you, and treat filtered water with that per the label directions. There are times I filter with the Sawyer, and use the Aqua Mira because it sometimes also makes nasty tasting water taste better. YMMV.

Yes, you can squeeze the reservoir. The Sawyer bags that come with the filter for doing this are notorious for going bad quite fast from this. It is recommended that you use another reservoir bag for this job. Or just use gravity. I will hang the bag, and open the valve when I need water. It's not fast, but it works, and no squeezing.

You can put the filter in line from your reservoir and just drink as needed. Easy peasy, stroll and sip. I use it this way most of the time. Stop at water source, fill bladder, close bladder, replace in pack, stroll and sip.

If the flow slows down, you back flush it with filtered water using the syringe that comes with the filter. No scrubbing or disassembly required.

Protect it from freezing. Like all water filters, if there is water in it, and it freezes, you compromise it's ability to filter out nasties. This is also a good reason to consider carrying Aqua Mira as a lightweight and very small backup to any filter system.

I like the Sawyer filter. Light, easy to clean, no moving parts, and the mini is very low priced compared to other filter systems.
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forester
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Re: Water Filter systems, Sawyer Mini questions....

Post by forester » February 7th, 2014, 8:13 pm

I have a Sawyer inline, but not the mini. Mine is a Sawyer 3-Way, which is a mechanical filter that sorts out everything but viruses. I like it. No complaints. The flow slows a little, but it's barely noticeable and it doesn't get in the way of drinking at all. I did end up buying a new hydration bag for it because I use Osprey bags and my old one, while great, used the non-industry standard hoses. I messed around with it for a while, then just bought a new Osprey bag with the normal hoses for $35. Everything fit and was hooked up within 15 minutes. I am pretty sure that Platypus will work with Sawyers without any problem.

I don't know about using it by squeezing or as a gravity filter. I don't think mine would work by squeezing the bag. ("Squeezing the bag", by the way, is a phrase that almost hurts to type...) I've only used it as a an inline filter. I think you can use them as a gravity filter, though. Overall, it's pretty slick and well worth the relatively slight cost. I have an anti-microbial bladder that I never have to rinse and, due to the filter, I can fill it up anywhere.

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retired jerry
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Re: Water Filter systems, Sawyer Mini questions....

Post by retired jerry » February 7th, 2014, 8:30 pm

Normally, you fill a container with untreated water, screw on the mini, squeeze the container, and a stream of treated water comes out of the mini. Fill a second bottle of treated water from the stream and drink from this.

You can also do a gravity mode rather than squeeze the container. Either just set it on a rock or bench and position the treated bottle below it under the stream. Or you can get some extra hoses and hang the untreated container and run the hose down to the treated bottle.

You could also suck like you said, but that's less common?

There's a problem with some Platypus containers. The thread pitch is slightly different so it's difficult to get the mini screwed onto it without a little water dribbling past it, which can drip into the treated water bottle, contaminating it. You just have to try it, or carefully measure the pitch with a ruler.

Sawyer has some collapsible water bags you can use. Many people have reported that these bags break, but I have used mine okay, but I'm careful. Sawyer came out with a new version of the bag that is supposedly more robust. I think it's a light blue color rather than black/dark blue.

Evernew has some collapsible bags that are good, but they're a little hard to find.

I just use a hard sided soda or water bottle. You can squeeze it better and I don't think it will ever break. But it takes up more room because it doesn't collapse.

The Squeeze and Mini have this one problem, you can't let it freeze. If you do, it may cause it to fail so it no longer filters effectively. If you blow on it it and air flows through easily, it's broken. If air doesn't flow through easily, it may or may not be okay. There's no definitive test.

I have this pet pieve. There are hollow tubes in the filter. To clean it, you backflush, the hollow tubes expand, so the pores expand and any particles are dislodged. Well, if it froze, that's what would happen, the hollow tubes would get expanded by the water expanding as it freezes. So it should be fine, as long as you shake out the water on the outside of the tubes. But they don't test this, they just say not to freeze it because they haven't tested it. If they did, they may find it's okay, which is a major defect for this otherwise great product. [/soapbox]

This filter does not purify, which means all creatures are eliminated. Only creatures bigger than 0.02 microns (or whatever it is) are filtered out.

I've been using the Squeeze for about a year. Best treatment method ever! The Squeeze weighs 3 ounces. The Mini weighs 2 ounces. I don't quite feel like getting it to save 1 ounce. I used to use Kathadyn but that weighs 12 ounces and you have to pump it. There are similar pump filters. You can use chemicals, but you have to wait, like, hours for it ot be effective. And bad taste. And unhealthful?

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Koda
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Re: Water Filter systems, Sawyer Mini questions....

Post by Koda » February 7th, 2014, 9:43 pm

Thanks for the replies... I've been on the fence, I have a fairly new MSR Hyperflow filter but its a love hate relationship. The Hyperlite isnt that heavy as far a pump filters go.... When it works it works great, but its finicky to maintain and gets airlocked constantly.

I wasn't certain about the purification part. I'm not worried about viruses around here just the usual suspects. But I figured it was a bonus if it blocked the viruses.

I think the Sawyer filter is just something I'm going to have to try to decide, maybe carry both for one trip in case. For 20 bucks on Amazon its hard to complain about a filter that lasts 30x longer than my MSR and doesn't airlock.


Jerry, I imagine the amount of expansion from freezing water is much greater than any amount mechanical pressure of backflushing can produce. Just my guess.
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retired jerry
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Re: Water Filter systems, Sawyer Mini questions....

Post by retired jerry » February 7th, 2014, 10:20 pm

Buy Mini - it's so cheap - about $20

Try it at home. 1 liter soda or water bottle works good if you have enough volume in your pack. Or get a collapsible bag or hoses. Run some water through it. If you like it, there's no reason to carry extra weight of a second filter.

The filter consists of hollow tubes, that have 0.02 micron (or whatever) pores in them. The inside of the hollow tubes go to the outlet of the filter. The inlet goes to the chamber outside of the tubes.

When it filters, the water goes from inlet, to chamber, through the pores to the inside of the hollow tubes, to the outlet.

When it freezes, water expands about 10%. If the entire filter was full of water, presumably the outer case could not expand 10% so it would crack.

If the chamber was empty of water (which you can do by shaking it vigorously) but the hollow tubes had water in them (there's no way to get that water out, too small) and it froze, each of the hollow tubes would have to expand 10%. I think they do that when you backflush. If so, there would be no damage - you can freeze filter as long as you shake the water out of the chamber. That would remove the big problem with this filter.

But Sawyer just says they don't know, so discard filter if you think it might have frozen. And there's no way to test it. They say to go ahead and use it for the rest of that trip though.

Some other hollow tube filter maker says you can blow on it, and if air flows through it, it broke from freezing. When you blow on a good filter, the amount of air flow is negligible.

Okay, I'll quit complaining now :)

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Koda
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Re: Water Filter systems, Sawyer Mini questions....

Post by Koda » February 7th, 2014, 11:30 pm

retired jerry wrote:The filter consists of hollow tubes, that have 0.02 micron (or whatever) pores in them. The inside of the hollow tubes go to the outlet of the filter. The inlet goes to the chamber outside of the tubes.
retired jerry wrote:If the chamber was empty of water (which you can do by shaking it vigorously) but the hollow tubes had water in them (there's no way to get that water out, too small) and it froze, each of the hollow tubes would have to expand 10%. I think they do that when you backflush. If so, there would be no damage - you can freeze filter as long as you shake the water out of the chamber. That would remove the big problem with this filter.
here is my hypothesis...
if the inside of the tubes lead to the outlet then they would compress during backflushing. A circle is mechanically strong... The tube is round, so it can take a lot of compression before collapsing, but not so much expanding from the inside.... Then, if the filter was shaken out but still had water in the tubes it would freeze randomly at various points putting unequal pressure points on the tube inside wall.
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retired jerry
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Re: Water Filter systems, Sawyer Mini questions....

Post by retired jerry » February 8th, 2014, 6:42 am

When the filter is used, water goes from outside the tubes, through the pores, and into the tubes

When the filter is backflushed, water goes from inside the tubes, through the pores, to outside the tubes. There's a lot of pressure on the inside of the tubes, which expands them, and the pores, so any trapped particles are released and washed away.

I don't know how much they expand, but if it's like 10%, then they should withstand freezing, unless they freeze unevenly like you said

It's kind of cool how it works. I think maybe they came from the world of dyalisis.

It would be nice if there was some test solution that consisted of dyed particles that were like 0.1 micron diameter. Run them through the filter. If the output was colored, then the filter doesn't work.

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Re: Water Filter systems, Sawyer Mini questions....

Post by renegadepilgrim » February 9th, 2014, 1:49 am

I have the Mini but have not had a chance to test it out. I also have the regular Squeeze, combined with two 1.5L Evernew bags and I can't complain. They work amazingly well. I used it all of last year and love it. I'm planning to take it on my trip to Nepal, along with a SteriPen for a backup.
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Re: Water Filter systems, Sawyer Mini questions....

Post by Lumpy » February 10th, 2014, 9:18 pm

Somewhere around here I have a Sawyer Squeeze that I know has been frozen and I no longer trust it. If I find it, I'll cut it open and take some pictures, and if I can find the proper magnification, I'll try to see if there is any freezing damage.
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