water filters

We have an under sink water filter. These things cost about fifty bucks for just the canister. You can't completely empty them. We use our moho for about 3-4 weeks out of the year. Cant we somehow use these again instead of throwing 50 bucks away and buying new ones just to use for a couple of weeks. Thats awful expensive filtered water. Besides with the exception of taste which is bad in some states we're not sure filtering campground water is all that necessary.We've been using rv parks( only) for several years and never caught anything from drinking their water. After all the owners drink it too.But it does help with the taste.
I've heard you can freeze them so nothing bad starts growing in them. Just thought I would ask your opinions on reusing.