Sanitizing fresh water tank? Bleach?

I also use Chlorine in powder form. Leave it overnight and then flush the next day with no residual taste or smell. It will kill everything. I try to do it once/year to be safe. I have this chore setup in my Automotive Wolf car maintenance software ( www.automotivewolf.com ) on my computer to keep track of it since the program creates a great vehicle maintenance log so I have a detailed record of everything that's been done on my RV. This software makes it esy for me to keep up with the maintenance on all my vehicles.