Having remembered instructions included with a backpacking personal water filter I have, I asked "Google AI" the following question:
"do camping water filters need anything between uses?"
And the reply was:
"Yes, camping water filters need cleaning and drying between uses to prevent bacteria and algae growth. After each trip, you should flush the filter with clean water and allow it to dry completely before storing it in a cool, dry place, preferably in a sealed bag. For long-term storage, some manufacturers recommend a more thorough cleaning with a diluted bleach solution or sanitization, and it's always best to follow the specific instructions for your filter model. "
Certainly makes sense to me.
Bill