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How to Prime an RV Water Pump Quickly? – 2 Methods

Written by Philip Lopez

Fact checked by Paul Lemaire

how to prime an rv water pump

Water pumps need to be properly primed before use. I made the biggest mistake of running my Shurflo water pump dry, and it caused severe damage. To protect mechanical seals and maintain an efficient flow of water, learn how to prime an RV water pump properly.

You only need a few things, like a water hose or some funnel. Simply fill the tank with water through a screened outlet or pour water on a prime line. Wait for the air to be released and build the pressure to pump water on all your water faucets.

Let’s detail the process of priming a 12 volt RV water pump below.

Method 1: Priming Through a Plumbing Fixture

water-pump-for-rv

Most RV water pumps prime themselves. All they need is a full fresh water tank. In this method, we’ll be filling water through a plumbing fixture.

What You’ll Need

  • Water hose

Step 1: Make Preparations For Priming RV Water Pump

After securing a long water hose, it’s time to perform the actual priming process. How long to prime RV water pump? It depends on your preparations.

  • Know your water pump location. The location is typically down the back or under the front bunks of your motorhome.
  • Make sure to turn off the power of your trailer water pump before priming it.
  • Find the plumbing fixture that offers access to the pump. This fixture is often closest to the water tank. It’s where you’ll pour water later.
  • Close all the water faucets inside your RV, except for the kitchen. You want to leave the kitchen faucet open to direct the water to only one source and make the priming process fast.

Step 2: Fill The Freshwater Chamber With Water

You have two ways to fill the chamber with water: through the plumbing fixture or the prime line. Before filling the pump body with water, allow it to cool thoroughly.

  • Get a water hose and run it with water for a few minutes to flush any contaminants.
  • Find the intake/local water supply valve on your RV.
  • Position the hose at the opening of this valve.
  • Spritz some water until the chamber is full.

Step 3: Test Water Pump For RV

Now, let’s test whether your pump will draw water into the water taps.

  • Turn the water pump on.
  • As the engine warms up, water pressure will feed into the pump and the faucet. You might hear some rumbling sound.
  • Once the water flows smoothly, you have been successful in priming the pump.
  • Don’t turn the faucet off just yet. Let the water run for several seconds to make sure that there’s no air trapped in it.

Method 2: Using a Prime Line

priming-rv-water-pump

If you’re in a hurry, you can install a prime line in your water pump when you need to build pressure. This process will remove the air out of your water lines and draw water in for all your taps.

What You’ll Need

  • Screwdriver
  • Rubber hose tubing or a clear hose
  • Garden hose with a nozzle or funnel and a pitcher of water

Step 1: Make The Prime Line

Instead of waiting for the RV water pump to prime itself, you can hasten the process with a dedicated prime line. Your prime line may either be a rubber hose or a clear hose that has the same size as your water line.

  • Cut the connection of your water outlet from the pump. Use a screwdriver to loosen and remove the screw from the pump’s collar.
  • Once removed, pull the water outlet hose from your pump. Be careful as some remaining water might leak out from the hose.
  • Attach the clear or rubber hose to the spout of the pump’s outlet. This hose will be your prime line where you’ll force water into.

Step 2: Pour Water

Next, we’ll be forcing water onto the prime line to get your pump working. It helps if you have a water hose with a nozzle that has a little nipple at the end.

  • Turn the pump on and the prime valve to the open position.
  • Insert the water hose nozzle into the prime line and begin pouring water. If you have no access to a hose, you can use a funnel and a pitcher of water.
  • You’re successfully priming the water pump when you hear the pump actually pumping water and water flows smoothly out of the faucet.
  • Once the prime valve is completely full, turn it to the close position to prevent any air from passing through.

Watch how to use a prime line to get your pump working again in this video.

Not Priming? Troubleshoot

Sometimes, water won’t flow through your faucet despite the priming process. Here are some troubleshooting tips when your camper water pump won’t prime.

  • Check for power. The first thing to check is the pump’s power. Some battery or wiring issues might hinder the pump from running.
  • Tighten the drain pipe. Apply several layers of thread seal to the drain pipe. This seal will help with the priming process and make the seal good. Fasten the couplers as tightly as possible.
  • Check the water lines. Find out whether there’s any leak problems leading to the fresh water tank and out of the holding tank. See if you can find any loose connections or cracks.
  • Remove blockage. A blockage in the supply line may also prevent the pump from functioning properly. Blow some light compressed air to remove the debris.
  • See if water is flowing. Try to disconnect the water line from the water pump to see if water is flowing. If you find some water in the line, all’s good. If it’s dry, the water line might be the issue.

Conclusion

That wraps up our article on how to prime an RV water pump properly. It takes a few trials to get it right as some underlying conditions might cause your faucets not to work. Always check your water pump manual to guide you on how to handle this equipment.

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