actually, don't add salt. Remember, water evaporates, not salt. Check your salt level after you add the water to your tank and adjust from there. Some bottled water or "distilled" water is poorly done and can have phosphates and other things in it and it could've been piped through copper pipes at the plant that can lead to a copper leach into the water. Just test it. Try to find a drinking water store and see how they process the water. R/O, DI? I have a store by my house that runs the water through 2 r/o systems, 2 carbon filters, DI and a UV sterilizer. All for $0.20 a gallon.