Fresh Water Fill Question

As far as sanitizing water tank every season, if yo use your unit like we do, at least once per month, filling the tanks with our city tap water should be enough sanitation. As OP stated, the water tank has never been used. that could mean hidden bacteria in and around the tank fittings, tank, etc where air, wamr temps and moisture is availbel without the continuous disinfection process a typical municipality uses. Please for your own safety, health and well being, fill, flush and sanitize your complete system. use about one cup of bleach in the water tank, through the hose or whatever. run water in the coach to insure you can smell it in all fixtures including hot. let it sit for at least 24 hours. flush all an do it again. this process will take about 3 full days. then final flush and fill again. you should be fine. if you smell a bit of chlorine, you should be fine, may get a bit of dry skin form a shower or a little bit of the runs from chlorine, but the alternative is worse. Good Luck & Be Safe ! ! !