It is quite common to only use your RV at certain times of the year and your water softener could spend several months not being used. When you know that you will not be using it for a while, you should disconnect it from the water supply. There should be valves and caps to prevent leakage. Drain all of the water out and take out the filter cartridges from the unit. Let them dry completely and then bring them into your home for storage. The rest of the water softener can be left in your RV until you are ready to head out again on an adventure.