Because most manufactured RVs are designed to be self-contained, they are equipped with a 12-volt pump to distribute water throughout the water system.

When turned on, this pump should run when water is being disbursed. If it periodically runs when water is not being disbursed then it’s likely that you are losing water pressure somewhere in your system, so check for leaks.

Also, according to RV pump manufacturers, scale buildup caused by minerals in the water can accumulate within your pump’s diaphragm as well as your system’s lines and this is the number one cause for a water pump failure. With that said, be sure to regularly clean the trap and screen located just before your water supply enters the pump. Here is an example of one of those pumps. If you need a replacement pump, be sure to read Mike’s article on the best RV water pumps.

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Cleaning your pump

To do this, turn off your water supply to your RV and be sure your pump is not turned on. Next, open a faucet to relieve any water pressure. Now, disconnect your incoming water line and then remove your trap and screen. Once you have done this, use a small brush to thoroughly clean the screen and the valve.

Priming the new pump

After you have made the repairs or installed your new pump, it may be necessary to prime the new (or old pump) to get it to properly work again. Quite often a pump won’t operate properly unless it has water within the pump. Sometimes it’s as simple as attaching your water supply line back on and simply opening up a kitchen faucet to activate the pump and draw water into the pump.

However, this may not always be the case. Occasionally, you will need to manually prime the pump before you re-attach the water supply line. To do this, use a funnel and hose and attach it the pumps intake line.

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For this type of priming you may need to enlist the help of a friend, because someone will need to open and close the faucet as well as turn on the electric pump if it is not an automatic pump. Once you have the faucet open and the pump is running, slowly pour water into the funnel until the water begins to flow out of the faucet.

Once this has been done, turn the pump off, close the faucet and immediately re-attach the intake line from your fresh-water tank or city supply line. Next, turn that outside supply line back on and you will have supplied the pump with the necessary water to keep it primed.

Now, you’ll want to turn more faucets on as well as the pump. After you’ve successfully blown the air out of the lines, your water system has been energized and you should be good to go. If you winterize your rig, this task will probably need to be done in the spring too. Just be sure to not let your pump run dry as it needs water within it to run correctly and to prevent it from seizing.