rk911 gave you some great advice. Let me add and maybe go a different route.
I am thinking of sanitizing the water lines. Look at the water pump, hopefully you will see a extra hose coming from a valve that may have a cap on the end. This hose and valve is used for two things one to winterize by sucking the RV Pink stuff out of the gal. jug into the lines. The second is sanitizing the lines after you flush them out with fresh water. Take a gal. jug fill with fresh water and bleach (i forget the amount of bleach to water) turn on pump one faucet at a time until you smell the bleach. Leave the bleach water in the lines for a short time. Then flush with fresh water again.
I would take this time to clean out the water heater. There is a plastic wand made for that. I think walmart even carries it. The wand will go in the water heater and hopefully clean out any particles that should not be there.
Good Luck