A 5th wheel has its RV service center on the driver side, non-curb side, of the unit. This is where you can connect your unit up to city water, disconnect the house batteries, and fill your unit’s fresh water tanks.
The RV service center has a city water connection that you can attach a hose rated for drinking water – white RV style – to it from a campground water source. Connecting the hose may be a bit difficult to put in due to the tight space, so it might be best to use a quick disconnect. The water that enters the RV service center will bypass the water pump and give pressurized water inside the unit. There is also a place where you can connect an outside hose to the RV service center, making it possible to install an outside shower.
If you want to fill your fresh water tanks through the RV service center, you can switch the valve so the city water goes directly to the fill tank. Just make sure to switch is back when done.
The RV service center also has a water heater bypass which allows you to add RV antifreeze during winterizing but not waste 6-12 gallons in the water heater. Simply drain the water heater, turn the switch to bypass, and fill the remaining water lines in the RV. Inside the compartment you will also see a red (hot) and blue (cold) water line with shut off valve.
You can easily drain the hot and cold water from the lines by opening the valve and draining to the ground. Keep in mind this might create a mess under the rig, so drain in a specified area.
There is also a black water tank cleaning system located at the service center. To operate the cleaning system attach a regular, non-drinking water hose to the unit and pressurized water will go through a wand that is inserted into the black water tank. The pressurized water will spray out, cleaning the side walls of the black water tank and especially the probes showing the level of fluid in the tank.
There is also a main battery disconnect located here, which will ensure everything with power is turned off when the unit is being stored.