On our Hemi 282, water tank inlet is next to the city water inlet marked, as aceinspp says, "Fresh Water Fill". There is no gravity fill, you have to use a hose with pressure.
Our tank is actually on the opposite side of the trailer by the entry door. Look underneath your trailer for the overflow and that should be where your tank is.
They put the water pumps in a variety of places, turn it on and listen for the location. Ours is under the kitchen sink.
Mark, Vicki, & Scout THE dog
2015 Hemisphere 282RK
2010 F250 Super Duty
1992 Goldwing Aspencade