How to Prime an RV Water Pump

How To Prime RV Water Pump

If you park your RV in campgrounds, even truck stops, you’ve probably connected into the water supply provided to you. That’s easy, as city water provides you with all the pressure you need to take a shower, flush your toilet, or use your sink. So, what happens when you aren’t attached to a water source?

That’s when you must rely on the water pump in your RV. The pump takes the water in your freshwater tank, and distributes it into your pipes so you can use it. Without a working water pump, the water you use will spit, dribble, or barely come out at all. One of the things you must do to keep your water pump in working order is prime it. Priming the pump is especially necessary for new water pumps, and pumps you haven’t used in quite awhile. Here are the instructions you need to do just that.

What is an RV Water Pump?

As mentioned above, an RV water pump works to send water from your tank to the rest of your RV with the appropriate amount of water pressure. To turn it on, you have to locate your water pump switch. When it works properly, you should have smooth, reliable water flow.

Most RV owners do not use their water pumps consistently. Usually, if you park at a campground, park, or truck stop you will tie into the city water supply that is provided to you. In that case, there’s no need to use your pump at all.

However, if you find yourself boondocking or dry camping, you will need a working water pump. This is when you camp without hooking up to water, sewer, or electric. 

Your water pump will run off of your RV battery, In the average RV, that will be a 12 volt battery. If you have a larger ‘tour bus style’ RV you might have a 24 volt battery. If you do, it’s important to choose a water pump that can handle that much power. Then, make sure your plumbing can handle it. You don’t want to overwhelm your plumbing with a highly pressurized rush of water.

In addition to ensuring that you have water, your pump ensures that you get your water consistently. In most recreational vehicles with rv roof coating this is at a rate of 3.5 gallons per minute for an average size vehicle, and 5.3 gallons for a larger vehicle. 

If you turn on your water, you should hear your water pump turn on. If you are hooked to city water, you won’t hear this as your system will bypass your water pump.

RV water pump

Where is The RV Water Pump Located?

Depending on your RV, you will usually find your water pump underneath one of your bench seats at the end of your RV where your water tank is located. Otherwise, it’s usually in a lower cabinet. If you can’t find it, look under your sink, and follow the water line backwards until you locate the pump.

You can also try turning the water pump switch on. You can then find the pump by following the sound it makes.

When you find your water pump, it may be behind an access panel of some sort. You should be able to remove this by simply unscrewing a few screws, and pulling away the access panel.

water pump types

Easy Steps For Priming Your RV Water Pump

Now that you have located your rv water pump, you can begin troubleshooting the issue. Once you ensure that nothing else is wrong, you can begin priming your pump.

Troubleshooting Your Water Pump

At this point, you’ve already done quite a bit of troubleshooting. You’ve realized that you aren’t getting enough water pressure. You’ve located your water pump, and you’ve removed the access panel. Now, briefly go through the following steps to make sure everything is okay.

  1. Look for kinked, pinched, or cracked water lines that could impact your water flow.
  2. Check for evidence of water leaks around your pump.
  3. Make sure your incoming and outgoing water lines are hooked up correctly.
  4. See if you need to replace your water filter.

If you are still having water flow issues, you will need to prime your pump. You should also prime your pump any time you install a new pump.

Priming Your RV Water Pump

  1. Get your equipment together. You will need a flat head screwdriver, a glass jar, rubber tubing, and some water. The rubber tubing should be the same diameter as the water line running out of your pump.
  2. Fill the glass jar with about 12 ounces of water.  You don’t have to be precise.
  3. Turn off the water pump at the switch.
  4. Disconnect the water line that runs out of the pump to the rest of your RV.
  5. To disconnect the water line, unscrew the screw in the collar around it until the line can be slipped off.
  6. Slip the collar off of the outgoing line, and onto your rubber hosing.
  7. Screw the clamp for the collar back into place so that the collar is firmly attached to your rubber hose.
  8. Now, your own rubber hosing is attached to the water pump instead of the hose that runs to your plumbing.
  9. Hold the attached hose in the air.
  10. Pour the 12 ounces of water into the hose.
  11. Place your thumb firmly over the top of the hose, and turn the water pump back on.
  12. Wait a minute for the system to pressurize.
  13. You will feel water pressing against your thumb as it tries to escape the hose.
  14. Once you feel that pressure, turn the water pump off.
  15. Disconnect the rubber tubing, and reconnect the water pump to your plumbing.
  16. Now, leave the pump off. Open up one of your faucets.
  17. Turn the pump back on again.

If everything has gone well, you should see a steady stream of water to your faucet. If you do not. Try another faucet or your rv shower head. If you still don’t get the pressure you should, something else is wrong. The issue is likely in the plumbing somewhere between your pump and your fixtures. If some most fixtures work properly but one does not, you can narrow the issue down to that fixture or the plumbing leading directly to it.

Gray And Black Water Pumps

The instructions above are for priming your freshwater pump only. You may also have a separate pump or macerator for dealing with water and waste that leaves your RV. These require different maintenance.

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Keeping Your RV Freshwater Pump in Good Repair

Unfortunately, many people realize their freshwater pump isn’t in working order just when they really need it. For example, you might pull into a stop with no available hookups. Now, you need your pump. Are you sure it will work like you need it to?

If it doesn’t you could be stuck bathing with wet wipes and bottled water. That’s not very fun. Even if you don’t use your pump regularly, you should hook it up every few months to test it out. That way you can replace or repair it before your next trip. 

If you do replace your unit, remember to purchase the best rv water pump you can. With this piece of equipment, going cheap to save money is nearly always a bad idea.

Final Thoughts

There are several steps you must take in order to prime your RV water pump. Fortunately, these steps are quite simple. Even better, you can complete the process quickly without any special tools. Remember this process in the event that you are not getting the constant water pressure that you should when you are boondocking or dry camping.

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