Today's RV's are made up of many RV Systems. Whether the RV is a mororhome or a towable, there are many common systems that make the modern RV so desirable. There are 2 electrical power systems, 120 volt AV and 12 Volt DC. There are 3 water systems consisting of the Fresh, Gray, and black tanks and associated plumbing, pump(s) and hardware. There may be a hydraulic system that operates the leveling jacks and often slide out rooms. Most RV's have an LP gas system that fuels appliances such as the hot water heater, gas range and oven, forced air furnaces, and absorption refrigerators that work on gas and 12 volt electric. Diesel motorhomes will also have an air compressor system to supply compressed air to the braking system as well as to the air horn and to the air bags in the suspension system.
RV water systems comprise water flow from the inlet coming from the campground hose bib through the Fresh Water System and then through either the fresh, gray or black Water Holding Tanks. The 12 volt water pump moves the water when not connected to park water.
Please understand that water quality varies from place to place, and you must filter the water you put in your rig. I feel this is such an important subject that I devoted a separate page to it. Check out this page on RV Water Filters.
The 12 Volt RV Electrical System provides 12 volt direct current for lights, appliances, and 12 volt outlets. A motorized RV will have a separate 12 volt electrical system to start the engine and provide control power for relays and solenoids. Both these systems are supplied from batteries.
The 120 Volt RV Electrical System provides 120 volts AC to outlets throughout the RV for AC powered appliances and other accessories. This power is supplied from the campground power pedestal or from an on board inverter on RVs so equipped.
LP (Propane) is stored in an on board storage tank and routed to gas powered appliances such as furnaces, ovens, range tops, hot water heaters, and forced air furnaces. There will be a regulator to adapt the gas pressure to the requirements of these appliances.
Most motorhomes and many towable RVs have hydraulic leveling jacks as well as hydraulically operated slide out rooms. Others have electrically operated slides and jacks. Most gas rigs have power assisted hydraulic brakes.
Almost all diesel motorhomes have both air brakes and air bags as part of the suspension system. There will be an engine powered air compressor and air tanks to hold the compressed air.