How to Fill an RV Water Heater

How to Fill an RV Water Heater

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Filling an RV water heater is a yearly event. Prior to storing the RV for the winter, all tanks are emptied to prevent damage from freezing (see Reference 1). For those who do not empty the tanks and use water system antifreeze, the system must be flushed prior to use. Filling the RV water heater does not take long. The amount of time to fill one depends on the size of the tank. Newer, high-end RVs and motor homes may not have a water heater tank. These systems are on demand and do not require filling.

Items you will need

  • Freshwater hose

  • Land based water source

  • Rags

  • Brush or canned air

Filling an RV Water Heater

Connect the RV water supply to a land-based water hookup such as an outdoor hose connection to your home. Use the RV's freshwater hose to make the connection. Check the freshwater tank to be sure it is full. Make sure that the water filter is installed. Open the water valve connection and add water to fill the freshwater tank if necessary.

Open the panel to the water heater. Check the water connection to the water heater to ensure the connection is secure. Connect the water supply to the water heater if necessary. Examine the pressure relief valve to make sure it is closed. If it is open, close it by flipping the handle down.

Examine the water heater to be sure it is off. The pilot light should not be visible on gas units. Disconnect the propane tank if the water heater runs on gas. If the unit runs on electricity, make sure the power switch is in the off position.

Turn on the water pump and open a hot water faucet. Listen for the sound of water entering the water tank and look for water coming out of the faucet. When water starts to run in a continuous stream out of the faucet; turn it off. Observe the tank and water connections for signs of leaking. If leaks are detected, stop filling the water heater and correct the situation. Once the water pump turns off and the tank is full; turn on the water heater. Use rags to wipe up any water spills.


  • Never turn on the RV water heater until the tank is full. Doing so will cause permanent damage to the unit.


  • When opening the water heater panel, expect to see spiders and other insects. Remove them with a brush or a blast of canned air. It is important to keep the area around the water heater clean and free of dirt and debris.
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