. . . We just got a new to us RV & drove it cross country & filled up with some water of unknown origin ( Could not notice any ill effects ). . .Have winterized the coach( removed the inline filters, drained the hot water tank & fresh water tank & then blew out the lines with compressed air ). . .When we are ready to use the RV & BEFORE I install new water filters ( one in the bay & one under the sink ) I will put some bleach into the system & fill the water tank; then run the solution thru the lines; then let sit overnite. . .Next day I will drain & blow out lines again; install new filters & I think it will be good enough for us. . .We have public water with is chlorinated & if we always get chlorinated water I feel good about not having to do this again. . .That is what I do FYI. . . We also ALWAYS drain the water tank when we return from a trip. . .