Did I freeze my sawyer squeeze filter to death?

Rhz,

I am guessing that it is likely that you are okay, but the only way that I can think of to test it is to find some silty water and filter it and see how it comes out.

I have filtered green looking water, which came out greenish on the otherside and drank a lot of that water and was fine.

According to the Sawyer representative that I spoke to at my local REI….happened that he was there the weekend after my trip of filtering green water….the rep said that things disolved at the molecular level will pass through the filter.

The example he gave was that if you filtered gatoraid, it would come out the other side still as gatoraide, color and all.

This is the one negative with the Sawyer….no way to really test its effectiveness.

That said, I think you should be safe because you were above freeze temperatures.

-Tony

On the web site they say they haven't tested it so to be safe, if you think you froze your filter, you should replace it.

There's no easy way to test it. Maybe if there was a test fluid of colored particles a little larger than 0.1 micron. Probably not wise to use an ad hoc test if you believe that water treatment is necesary.

Your's is a perfect example why Sawyer should resolve this. It is unreasonable to just say to replace the filter if you suspect it might have frozen. In real use, it occasionally goes below freezing and unreasonable to guarantee that it never freezes.

In Roger's article, he says when you backflush, it expands the tubes a little which helps dislodge any particles clogging the pores. Thus, they should be able to survive freezing.

I think I'm just going to ignore this. Shake the filter out vigorously if I think it might freeze so the case won't crack.

Rafi,

I suggest you call Sawyer.

When I had a flow problem they were able to solve my problem with suggestions that were not otherwise available to me. They may have some info that we don't have.

Here's one idea, however. Did you use the filter early in the morning right after the night of possible freezing? If you did and it flowed normally then it probably didn't freeze. If it didn't flow normally then it might have frozen and was possbibly still frozen when you used it.

Daryl

Thanks for the responses. The filter was not used on the trip. I'm sure it had a small amount of residual water inside, but I did shake it out vigorously prior to the trip.

I did put a call in to Sawyer. The customer service rep basically told me to replace the filter. I did leave a message for an engineer at Sawyer who will (hopefully) call me back.

If it did go beneath freezing, I'm pretty sure it was only for a short period of time. That night, the filter was inside a dry sack in my daypack in the trunk of my car.

Thanks again.

rhz

Rhz,

From a liability point of view, they have no choice but to say to replace the filter or face possible legal reprecussions if you got sick from using the filter.

What we don't know is how elastic the plastic hollow tubes are.

Would they flex/stretch enough to survive freezing and the expansion?

Too many variables to account for.

Freezing is the death of any filter, not just this one.

If your filter was full of water and then froze, then I would say that you need to buy another one.

From what you described, I think you would be okay.

Another way to check…if you filter some water and find that the rate of flow is significantly faster, then it might be a sign that some of the hollow tubes have ruptured and are just letting untreated water pass through the system.

-Tony

This might be a simple test (for the future) and for people who use the Sawyer as a gravity filter. When the filter is new, fill the upper bag with clean water (distilled? Known good tap water). Filter the water into a say, Nalgen bottle. Measure the time it takes to fill the bottle from 200 ml to 1000 ml. To check the filter (like after a freeze) run the test again (same heights, same water source, etc.). If your time is less than your original reading your filter is bad (true positive?). If it is longer, you won’t know for sure (false negative?). Hey, it’s an idea anyway. I am sure that it can be refined. My 2 cents – Jon

Contaminate water with bacteria.
Filter.
Plate filtered water and count colonies.

One problem with the flow rate test, is that the flow rate varies

Like Daryl experienced

Or, when you start running water through, the flow is lower, then it speeds up as it gets wetted

It may be difficult to differentiate between normal flow rate variation and what would happen if some of the holes were bigger or split open

I once found myself in the same situation with a Platypus Gravity filter and wasn’t sure whether the hollow fibers were damaged by freezing temperatures.

Cascade design has the following information on their FAQ website

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What about freezing?
Once you have used your CleanStream™ filter and wet the Hollow Fiber filter media, the fibers will remain wet for a very long time. Therefore, it is important to prevent it from freezing, which can permanently damage the filter media. If you are traveling in areas where you are expecting freezing or near freezing temperatures, bring the filter into your tent, or even your sleeping bag. The included, watertight hose barb covers will prevent any leakage wherever you store it. If you think your filter may have been damaged by freezing, perform a Filter Test before the next use.

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The test described in the linked PDF document is really easy to do – just blow through the filter from the clean end. If you can’t do it, the filter is OK. If you can blow air through it, it is damaged.

Assuming that the Sawyer filter uses similar hollow fibers, the same test might work for your filter.

Manfred

A few anecdotes on this subject:

Much like you, I left mine in a gear tote in the garage for a few nights about 2 months after its last use and 'shake-out', and it *may* have frozen on one of those nights. I contacted Sawyer and they told me that it needed to be replaced. I'm sure capitalism had some factor in this company statement, but I also got a decent explanation why, as outlined by above posters. Essentially the element pores get stretched out to something larger than the 0.1 micron it was created with.
FWIW, I have not replaced my 3-way, and am not sure I plan to for a 'maybe'

As for the water-in-the-filter issue, somewhere here on BPL a member posted about how they took a filter of another brand that became nonfunctional, and after a year of sitting on a shelf, cut it open for kicks to see inside. The ceramic element was, by his account, still wet. This just illustrates that a filter never *truly* dries out.

My personal opinion, if you aren't sure it got below freezing, and it was in the trunk of your car with other objects which potentially kept the trunk slightly warmer than the ambient air low temp outside the trunk, you're probably OK.
In the end, go with your gut, you're the one drinking the water.

No idea about bio-chem, but would this be possible? Could you order something per-contaminated?
"Contaminate water with bacteria.
Filter.
Plate filtered water and count colonies."

Is there some sort of indicator you could mix with the filtered solution to react with the bacteria? I would feel somewhat strange justifying a microscope purchase with "…err I need this for my backpacking gear"