An easy way to introduce chlorine or whatever product (dry or liquid) through the entire water system is to use the Miracle-Grow or other siphon type of hose-end sprayer. Simply unscrew and remove the spray end and attach a hose which will have the other end connected to the fresh water fill on the bus. Of course the water entry end of the spray bottle will be connected with a hose to the fresh water supply. Then add the appropriate amount of chemical to the container. This will allow the diluted mixture to be introduced gradually rather than directly into the tank. This method should avoid spills and the bottle can be used for storage of the chemical for the next treatment.

Costco sells the RO systems for well under $200.00. They DO take up some space. A complete set of replacement filters are under $40. I've had two of them and they work great