Last updated on January 31st, 2019
The answer is yes, it could. The water filter cartridge could freeze and become damaged as a result of freezing temperatures.
Many of us have at least one portable water filter. We might take them along while hiking, camping, on a hunting excursion, or dedicated to a survival kit, bug out bag, or other usage scenarios. Be aware of cold temperature issues!
Freezing Temperatures & Water Filter Media
Have you ever wondered if your water filter might be damaged if it gets below freezing?
Maybe you’ve not thought about it before, but you should…
Why? Because freezing temperatures may damage the water filter element –
…and you won’t even know it!
That’s right, the internal filter media (cartridge) might crack. And then when you go to use it – the filter will be inadequate, allowing contaminants to get through.
How do cold temperatures damage it?
When it freezes, ice crystals embed within the filter media. This may crack, expand, or form ‘holes’ within the water filter cartridge itself which are larger than the filter’s pore size. This will result in raw unfiltered water to flow through without being properly filtered.
How do I know if the water filter is broken?
The thing is, there is no absolute way to know if your water filter has been damaged from freezing temperatures.
You don’t want to find out by getting sick!
By the way, the ‘food coloring’ test is not definitive. It’s water soluble so it may get through the filter pores anyway indicating a false-positive. “Most dyes go into solution (molecular), not suspension (particle) form”. Note that a charcoal filter stage may absorb food coloring, but charcoal is for neutralization of odor and flavor.
You might check with the filter manufacturer website and FAQ (frequently-asked-questions) to discover whether or not your filter is susceptible to freeze damage.
Generally speaking, if the filter element has been used and therefore is wet, the water inside will freeze at temperatures below 32-degrees-F and will likely crack, damage, or destroy the filter media inside.
Note: A water filter’s internal media will remain wet for a very long time, even after draining it or not using it for awhile. In my opinion, depending on filter media this could be weeks or longer. I believe I’ve read (from Sawyer?) that once it’s used once it will never fully dry.
The Good News
Fortunately these portable water filters are not expensive.
So replacement doesn’t hurt so much.
FROZEN LIFESTRAW WATER FILTER
Here’s what they say on the LifeStraw website:
“If your LifeStraw has been used, and is then exposed to freezing temperatures, water inside can freeze and crack the filter. You may not see these cracks, so we recommend never letting it freeze once it’s been used. When camping at high elevations or freezing temperatures, be extra careful not to let it freeze.”
SAWYER FILTER & FREEZING TEMPERATURES
Here’s what they say on the Sawyer website:
Before initial wetting
Filter is safe from freezing temperatures if it has never been wetted.
After initial wetting
While there is no definitive way to tell if a filter has been damaged due to freezing, Sawyer recommends replacing your filter if you suspect that it has been frozen.
If you are in freezing temperatures, we recommend that you store your filter in your pocket or close to your person so that your body heat can prevent freezing.
Tips To Protect Water Filter From Freezing
In freezing temperatures, carry your portable water filter close to your body.
Keep it inside your jacket.
Keep your water filter in your sleeping bag at night.
Alternative Water Purification During Cold Temperatures
Boil your water
During the winter (or any time) boiling water always works in place of a filter.
How Long To Boil Drinking Water?
UV Ultra Violet
A Steripen is a good choice during very cold temperatures. The ultra violet radiation will destroy organic contaminants.
I advise that you use Lithium batteries during winter because they are excellent performers when it’s cold:
Lithium AA batteries
Use chemical water treatment instead of filter when it’s that cold: