We have a under counter cartridge for the ice maker and separate drinking faucet. It is change yearly because water sittin it with the contaminents it removed brew more of them. The silver in it destorys them but still needs to be replaced. We use one or up to three filters to the coach depending on the need. A heavy load of sediments hits the first coarse carbon block filter, and then the second carbon block with silver and other things to get metals etc ad both get chlorine. A third .09 micron filter if there is sulfur etc still getting through the other two. No bad water goes into the tank. It is filled with city water through the filter and gets rid of the chlorine and other chemicals and nasties before we leave. A good carbon block or ceramic filter with a carbon block will get a lot of lime, that is usspended in the water. Won't get the dissolved except as it goes around the trapped suspended particles it will cling to them. If the tanks go awry the under sink filter will get whatever. Save the planet and don't buy plastic bottled water and ours tast better.