Yeap. That is a thorough description of the Gravity Fresh Water Fill.. To test it
and as described in the Manual "How to know FWT is Full".
Connect a water hose to city water connection and turn the selector valve to FILL. Turn on the water to the connected hose, walk to the curb side of the rig, unlock that little Gravity Fill compartment and take that little cap off. Go do something else for a long time (110 gallons). If you come back and water is only coming out the Gravity Fill. All is Good.and more important your FWT is now Full
Added. Do not tell canesfan