OK, I've always heard the gravity filters anyway have a kind of micro somethings and if they freeze they are no good. How would you know this? And if you never had water in it and it froze, would it be wrecked.

I think you would be OK if it never had water in it before but you may want to e-mail Sawyer or any of the other manufacturers. I think you can do this via Cabelas or Amazon.

Sawyer and similar hollow tube filters use the permeable surface of the tubes as the filter medium. Water in the tubes freezing will expand and rupture the tube.
No sure way to test it at home. The broken tubes will allow water to pass unfiltered. Best to replace it.

The only home testing for filters I know of is from First Need for the type of matrix filters they use. Consisting of a solids based food dye.

butthead

If you never had water in it the filter medium should be fine. It's only if you had water in it that a rupture in the filter medium could cause you problems.

You could test it by using it and if you got the trots a short time after your trip you know it's bad. :-)

For long term storage MSR says to remove the pump from the filter and dry it out, then put into a bag and into the freezer. I would only do this to a filter that can be dried out.
This is because the filter can be taken apart down to the exposed filter member.

With the First need filters I replace after two trips. I always brought another filter cartridge with me just in case. Don’t freeze these.

With the Sawyer filters I just back flush them and they are good for a crazy long time. Don’t freeze these.

I also run a diluted solution of water and a 1/4 cup of bleach to a gallon through my filters for storage over the winter. Not sure if this is the correct thing to do, but I do know that bleach kills germs and nasties in water. After I run the bleach I flush with clean water and store away.

I’m not by no means an expert here on filters, just what I do.

Sawyer and most MSR (except the MiniWorks ceramic), filters use hollow fiber.
The FirstNeed is structured matrix (big block of synthetic fibers).
Other filters usually are solid ceramic or porous bronze. Freezing water will destroy all because of the expansion when ice crystals form.
If you think the filter froze when wet, it's best to replace it.

butthead

Savage Voyageur: "For long term storage MSR says to remove the pump from the filter and dry it out, then put into a bag and into the freezer. I would only do this to a filter that can be dried out.
This is because the filter can be taken apart down to the exposed filter member.


With the First need filters I replace after two trips. I always brought another filter cartridge with me just in case. Don’t freeze these.


With the Sawyer filters I just back flush them and they are good for a crazy long time. Don’t freeze these.


I also run a diluted solution of water and a 1/4 cup of bleach to a gallon through my filters for storage over the winter. Not sure if this is the correct thing to do, but I do know that bleach kills germs and nasties in water. After I run the bleach I flush with clean water and store away.

I’m not by no means an expert here on filters, just what I do. "

That's what I do too. Except I use vinegar to disinfect then backflush twice. No bacteria survives vinegar. Then, exposed filter component in the sunshine till dry. The dash of my truck works well as a spot to dry. Stored in ziplock till I assemble for an upcoming BWCA trip. Tip: pour some vinegar down your P-traps at home to 'sweeten' p-traps.

Here's the MSR Trailshot testing instructions:
Trailshot Integrity Test

Try a Google search to find instructions for other brands (if they exist).

arm2008: "Here's the MSR Trailshot testing instructions:
Trailshot Integrity Test


Try a Google search to find instructions for other brands (if they exist)."

That is how I backflush it but figure if the hollow fibers have been burst due to freezing the flow will go both directions in spite of the check valve. Something to look into further.

butthead

Sometimes there might be the question whether it froze or not. Or how froze? I assume a new filter never used would be OK. I bring filter on the road as a just in case. My truck never freezes inside. But gets cold sometimes.
Thanks for the input... And on the viniger, I've found out just how valuable that is.
I did send Sawyer a question on this... I'll report when I hear back.

How to tell if the filter is no good??? When you get the sheets after drinking from it :)

This message has had HTML content edited out of it.
This is what I got...



Hello Ben,

Thank you for reaching out to us and for using our filter. Unfortunately there is no easy way to test if the filter has been damaged. We do freeze damage testing as a part of our ongoing filter longevity tests, but this process costs more than replacing the unit. If your filter is ever frozen, we recommend erring on the side of caution and replacing it.

There is no threat of freeze damage with an unused filter. However, once the filter has been used it is susceptible.

Let us know if you have any other questions or comments,


Sawyer Customer Service
800.356.7811 x 15
www.sawyer.com
Facebook
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On Tue, Apr 3, 2018 at 3:18 AM, Ben Cardelli via Sawyer Products wrote:
Name: Ben Cardelli

Email: nctryben@gmail.com

Page: FAQs

QUESTION:
I understand when my Sawyer filter freezes it will ruin the micro membranes or whatever. My question is if there is question whether it froze or not. Is there a way to test it? Late or early season camping puts us in subfreezing temps. Also if dry, freezing OK?

nctry: "This is what I got...

Hello Ben,

Thank you for reaching out to us and for using our filter. Unfortunately there is no easy way to test if the filter has been damaged. We do freeze damage testing as a part of our ongoing filter longevity tests, but this process costs more than replacing the unit. If your filter is ever frozen, we recommend erring on the side of caution and replacing it.


There is no threat of freeze damage with an unused filter. However, once the filter has been used it is susceptible.


Let us know if you have any other questions or comments,
"

So basically, if you think it might have froze replace it with a Trailshot, which you can test. Sadly, mine apparently did freeze this winter as it failed when I tested it. I only used it twice, then forgot it was in my pack in the car :-(

April

"So basically, if you think it might have froze replace it with a Trailshot, which you can test."

While MSR listed a way to test the Trailshot, it uses the same style of hollow fiber filter system that Saywer said it had no reliable way to test. Choose wisely which advise to use.

butthead

butthead: ""So basically, if you think it might have froze replace it with a Trailshot, which you can test."
While MSR listed a way to test the Trailshot, it uses the same style of hollow fiber filter system that Saywer said it had no reliable way to test. Choose wisely which advise to use.
butthead "

My assumption is that it can't be tested because of the design. I could be wrong. The Trailshot gives instructions. Maybe they are blowing smoke.

This message has had HTML content edited out of it.

nctry: "This is what I got...



Hello Ben,


Thank you for reaching out to us and for using our filter. Unfortunately there is no easy way to test if the filter has been damaged. We do freeze damage testing as a part of our ongoing filter longevity tests, but this process costs more than replacing the unit. If your filter is ever frozen, we recommend erring on the side of caution and replacing it.


There is no threat of freeze damage with an unused filter. However, once the filter has been used it is susceptible.


Let us know if you have any other questions or comments,



Sawyer Customer Service
800.356.7811 x 15
www.sawyer.com
Facebook
Instagram
Twitter




On Tue, Apr 3, 2018 at 3:18 AM, Ben Cardelli via Sawyer Products wrote:
Name: Ben Cardelli


Email: nctryben@gmail.com


Page: FAQs


QUESTION:
I understand when my Sawyer filter freezes it will ruin the micro membranes or whatever. My question is if there is question whether it froze or not. Is there a way to test it? Late or early season camping puts us in subfreezing temps. Also if dry, freezing OK?




"

If your filter gas never been used it can withstand freezing. The problem is if you use it you never know if it’s completely dry so if it has any moisture in it, it can freeze and thus damage the filter. So basically if you are going to be out and there is any chance the temperatures are going to be down low enough to freeze protect your filter.

OldFingers57: "


If your filter gas never been used it can withstand freezing. The problem is if you use it you never know if it’s completely dry so if it has any moisture in it, it can freeze and thus damage the filter. So basically if you are going to be out and there is any chance the temperatures are going to be down low enough to freeze protect your filter. "

That is what we do... But there's always that time in the shoulder season where your out there in sub freezing weather where you even after taking precautions including putting it in the sleeping bag with us where you might wonder if you let it freeze. Not always I guess, but it's happened. Sometimes you wake up to much colder than you think it was supposed to get...