Cities spend a lot of money treating your drinking water with the appropriate chemicals.  The cleanliness and type of hose you use to fill your tank with are just as important to consider as chemical treatments.  If you are uncertain of the source or water reports indicate high levels of certain contaminants, it may be more important to filter your water than to treat it with chemicals.  Unscented bleach and FDA approved water tablets will prolong the life of your source and kill any residual bacteria. Rockwell Water Systems promotes regular rotation and filtration before adding more chemicals