How do you flush out the fresh water tank?

Thank you so much. I'll check the videos. LOVE Youtube.

go to google and ask then watch the U tube. theres ways to do it, but this way you,ll get to watch

You are right about what you need to do. Use 1/4 cup bleach for every 10 gallons of water capacity, including the water heater. Pump the mixture through the lines by opening all the water outlets, hot and cold. You want to fill up the water heater with this, too.

Let it all sit for 4 hours MINIMUM. Then drain the tank, refill with potable water, and run all the water outlets until they don't smell like bleach any more. This may take a couple of tank fills.

Before sanitizing is a good time to clean out the water heater tank. Remove the drain plug, drain all the contents (if any) and flush out the sediment.
There should be a valve sticking down from the bottom of the motorhome, somewhere.

Be sure the water heater is NOT on bypass. You want to fill it up with the bleach mixture.

There are lots of good videos on how to do this. Just google "how to sanitize rv water system" or "how to flush rv water heater" and you will get tons of info.

There should be a drain sticking down below the motor home to drain the tank. The valve may be visible on the drain, or it might be up by the tank.