Thanks all for your replies. It is always good to hear how other folks do things and pick up valuable info. We are fortunate to live rural and have a deep well with ultra pure spring water. It is always 48 degrees when it comes out of the faucet and has absolutely no taste.
That said when we go on long trips and we use all of our own water it is hard to drink other stuff.
I too use 1/4 cup bleach in 20 gallons of water and let it sit all night at the start of the season. I have to winterize it with the RV antifreeze and have to flush the system a few times to get that all out. When we leave here in the winter the tank will be winterized so will have to leave it that way unless I can find a spigot (I carry the hose in the wheel well area. I then carry (2) the suitcase water 2.5 gallons.
It seems like we all have similar habits on cleaning the pipes/tank. I wonder at what point the tanks need replacing ? I am probably overthinking it as usual!
Rob