Since we still w#$k, we use our rig several weekends from April into October, and a 2-week trip during the summer. I sanitize the fresh water tank in the spring using clorox - run it through the lines and let it sit a couple of days; then fill and dump a couple of times. We use the water for everything, including cooking and drinking, and have never had a problem.
After I trip I dump all the water, unless we are going to use the rig the next weekend - then I just add more as needed. We always travel with a full tank (65 gal). During our 2-week trip we might have to add more, depending on the type of hookups we get during the trip, and the water condition - some parts of the country have very bad-tasting water.
'05 NuWa 29.5 lktg HitchHiker II
'05 Chev 3500 4X4 Crew LB SRW Duramax/Alison