I installed the water inlet and vent. Located under the stainless steel clam shell is the vent comprised of the copper pipe with screen shown earlier. I sealed all the surface joints with GE grey polyurethane sealant for windows and doors. I had to order it online from Home Depot as it was not readily available locally. The inlet has a builtin regulator that limits water pressure to 40 psi. When filling the tank I'll need to be careful not to overwhelm the vents overflow ability as the tank wasn't designed to be pressurized.
Installed the Water Tank Inlet & Vent