Sanitizing your RV water storage tank

All this dialogue on santitizing your water tank gets me to thinking. Due some physical issues, we have not taken our RV out in a while (several months). I have drained my RV water tank twice . I have put 1/4 cup of bleach in it every time I refill it. So my question is: How do yall sanitize you water storage tank. The other question when hooked up to shore facilities i.e. potable water bib. does that water go directly into your water storage tank then to your water faucets or does shore water stay in pipes then go to the faucets in or out of the RV?