I sanitized the system before each summer trip of 3-4 months.
I drain the fresh water tank, remove the water filter, and pour Clorox bleach into the hose. (Using Mfg Ratio)
Connect the hose to the water faucet and fill the tank.
Run the faucets in all the areas until a faint odor of Clorox bleach is noticed.
Let it sit for 4 hours or more.
Drain the tank, refill and drain once more (gets rid of Clorox bleach taste.)
Put the filter back in and fill the tank to whatever capacity you wish.
Tip: if you have a short hose, hook it to the water faucet and after putting Clorox bleach in the other hose you can keep the Clorox bleach from draining by holding up both ends of the hoses and connecting.