if a 2016 is plumbing like my '14, then the incoming water to fill your tank goes thru the FILTER, then the PUMP, then thru the 4-Way VALVE, and then into the tank(or into the lines if you are staying on pressurized water).
While it goes thru the water pump, the pump only will be used when you have the 4-way valve turned to 'Normal', and you have the water pump switch ON, therefore drawing water FROM the water tank.
When FILLING the water tank, the same path is taken, except the 4-way valve is turned to 'FILL TANK', and the pressurized water then flow thru into the tank. When the tank is full, and you forget to shut off the incoming water, the OVERFLOW tubes allow the additional water a way out, otherwise your tank could burst. This causes no issues with your water system, though, as the tank overflow tubes are there just for that reason. They are also there so that when you use the water pump, pulling water from the tank, a VACUUM is not caused in the water tank, creating the potential for 'implosion' of the tank....AIR is generally your friend!
Now, if you are experiencing what others of us have, which is the filling of the Water Tank when you are not 'expecting' it...then you have a leak within the cartridge of the 4-way Anderson 'KantLeak' valve system. The cartridge is what you are turning when you move the Valve handle. It has 4 'directions', depending on what you are wanting to do, and each has a hole, or holes, with rubber washers. These washers can get out of alignment with the hole, or move completely out of their space, causing either an air leak in the system, or for water to flow into the water tank when you are on pressurized 'city water'.
I decided after changing out my Anderson Cartridge several times, that is would be easier in the long run to just install a standard water 'cut off' valve in the line that leads into the water tank. It works fine, as long as you remember to cut it off when you don't want the tank to 'fill', and back ON when you want to use the water pump.
I actually like it, too, as it now gives me control over filling my water tank at the same time I can use water within the coach. If we arrive at a park and I know I'll want to fill the tank before we leave, I just open the installed cut off valve, and monitor it over the next few hours, turning it off when the tank level is where I want it to be. Nice. : )
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Hiawassee, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )