Storage and the water filter
What to do with a water filter when the RV goes into storage.by Steve Pally
Here is advice from the VP of Rainfresh Water Filters on the subject. Information provided by Steve Pally, with permission from the author.
If a cartridge has some life left in it and therefore some monetary value, then saving it for future use makes sense. Fortunately most our our disposable cartridges are relatively inexpensive and in most cases not "worth" trying to save.
For those that do want to save a cartridge for future use, our advice has always been to take cartridges out of the housings that they are in and lay them in the sink (or shelf or other convenient location) and allow them to dry out thoroughly before freezing temperatures might freeze the water left in the cartridge and cause the cartridge to break/crack. For example it might take 7 to 10 days for the water in one of our ceramic cartridges to evaporate.
Even if the temperature is not likely to fall below freezing, we think it's a good idea to allow the cartridge to thoroughly dry out, so as to minimize/eliminate the opportunity for bacteria to grow.
Having said that, there still might be an opportunity for organics trapped in the cartridge to cause a bad taste/odour when the cartridge is reused. This should not be a health concern, more of an aesthetic situation, and should not last for any great length of time.
We do not think that cartridges should be stored with water in them, or stored in water in a bag. Either situation could result in a bacteriological growth in the cartridge which might prove to be problematic next year. And of course in freezing temperatures would most likely result in a broken cartridge.
A further note on filter housings. Most housings have an O-ring seal or two in them and when taken out of service (i.e. opened to remove cartridge(s) and drain for the winter) these seals can dry out over the period that the seals are open to circulating air and then crack when used next year, causing leaks.
Our advice is to reassemble the housings, provided you are sure that ALL of the water is out of the housing. If you can't be confident that all the water has been taken out of the housing, or that some water from the lines might not get back into the housing, then we suggest taking everything apart, removing as much water as possible and then wrapping the head (with the seals) in an airtight bag so as to minimize the opportunity for the seals to dry out. If there is some water left in the system, hopefully with the housing not reassembled there will be enough "space" for the water to freeze without cracking the head.