Flush that sucker with a quart of bleach in 100 gallons. Ride down along rough road and drain fill drain. And always use a great filter, not just a good filter and certified drinking water hose, the little aluminized label is what to look for. Also if you use white translucent cheap water hose and let it lay in the sun between faucet and coach it will grow algae and other things and the inside will turn brown with it and...it will make it's way into your tank unless you have a good filter.
The Culligan fresh water chlorine add some to your tank if sitting for a few days, according to label reccomendtions not household bleach or pool chlorine.
Better still is to pay the 30.00 or so for the saantizing kit it won't leave you water tasting like clorox for a few/several days after sanitizing.