Air in your RV’s water lines is not uncommon, but if your plumbing system has this issue, you’ll want to fix it as soon as possible. While air pockets in water lines don’t present a particularly urgent issue, an RV that has air in the water pipes is a nuisance and could potentially burn out your water pump. In this post, we’ll show you how to deal with air bubbles in your water system so you’ll be well-prepared if you ever encounter them.
What Are the Symptoms of Air in a Water System?
Air in water lines can present itself in a few different ways. Let’s take a look at what might alert you to air in your rig’s water system.
Loss of Water Pressure
We’ve written about low water pressure in an RV before, but one thing we didn’t specifically mention in that post was the possibility that air in the plumbing system could be causing it. If you’ve noticed a loss of water pressure in your RV, you may have air in your water lines.
Water Hammer Noise
Air in a plumbing system often manifests as a pounding noise. This can usually be attributed to something known as “water hammer”. Water hammer can occur in any plumbing system where water-supply valves control water flow. So if you’ve got noises coming from your pipes, it’s possible that you have air in your water lines.
Sputtering Water
Air in water lines can cause water to sputter or spray from the faucet. This can have other causes (as the previous two symptoms may), but water sputtering or splashing from the faucet may indicate air in your RV’s plumbing system.
If water sprays or sputters out of the faucet, this could be symptomatic of air in your RV water lines.
What Causes Air in Water Lines?
Aside from being introduced by disconnecting and reconnecting to city water when hooking up at an RV park (or when switching between the city water source and your onboard water pump), air in your plumbing system can result from any of a few different issues.
Water System Maintenance
If someone has turned off the water supply to your plumbing system for maintenance or another issue, air may have entered the system. When the water supply is cut off, air can enter a plumbing system. This can be very easy to resolve, sometimes by simply running a faucet for a minute or so, though this is not always the case.
Leak or Hole in the Plumbing System
If there’s a leak in your RV’s hot or cold water pipes, air can enter or become trapped in the plumbing system.
Leaking or Damaged Valve
If a valve in your RV’s plumbing system is leaking or damaged, it can also cause air pockets to build up in the system. For example, this could occur if an RV’s plumbing hasn’t been properly winterized and a valve (or pipe) cracks in the cold (see our RV winterizing tips!). If springtime comes and you de-winterize your rig and your water pump keeps running, you may have a cracked, leaking, or otherwise damaged valve somewhere in the system, and this can possibly introduce air into the system (and cause water damage from a leak).
PRO TIP: If the sputtering or water hammer noise is occuring right after you’ve de-winterized your RV’s plumbing, the cause could be that you haven’t properly returned any bypass or winterizing kit valves back to their normal operating position. Check and double check all valves to be sure you’ve put them back the way they should be.
RV pipes, valves, and fittings can crack in cold weather if a rig isn’t properly winterized.
Loose Connections
Sometimes the culprit is simply a loose connection somewhere in your RV’s plumbing system. Loose connections are generally found where pipes and valves are connected.
Faulty Water Heater Thermostat
A faulty water heater thermostat can cause hot pockets to form. This can, in turn, trap air in the plumbing system. If your water is too hot and/or you hear a gurgling sound at your faucets, the issue could be a faulty water heater thermostat.
Faulty Pressure Relief Valve
There’s an outside chance that the source of air in your water lines could be related to a bad/leaky water heater pressure relief valve. If this is the cause, you’ll likely have the issue with sputtering only when running the hot water at the faucet.
In this photo, you can see the pressure relief valve noted at the top and the anode rod at the bottom. Note that this is a Suburban water heater. An Atwood RV water heater has a pressure relief valve like this one but has a drain valve/drain plug instead of an anode rod. From the outside of the hot water tank, these two items look very similar.
How to Bleed Air from RV Water Lines
There are a couple of ways to bleed the air from your RV’s plumbing system.
Using the Municipal/City Water System
If you have access to a municipal water system at your home or elsewhere, it’s the quickest way to bleed the air from your RV’s water lines.
- Connect your RV’s plumbing system to a pressurized water system such as the one at your home.
- Open the pressurized faucet (where you’ve connected the hose to your home).
- Open all of the faucets inside your RV. Don’t forget the shower(s) and any outside faucets.
- Once the water pressure returns to normal and there’s no sputtering/splashing at any of the faucets, turn them all off and then disconnect the pressurized water source.
- Turn on your RV’s water pump. The pump should prime itself and start working properly.
- Once the pump stops running, open each faucet and allow water to run, then turn it off and test the next one.
Using Water from the Freshwater Tank
If you have no choice but to use water from your freshwater tank to bleed the air out of your RV’s water lines because you can’t connect to a pressurized system, take the following steps.
- Fill your fresh water tank if possible.
- Turn on the RV’s water pump. This will pressurize the water system.
- Open the faucet in the RV that is farthest from the freshwater tank. Let the water run for a while until the water stops sputtering and flows freely. Turn off the faucet.
- Repeat with the other faucets until they each run smoothly.
Note: Try not to do this when you’re boondocking unless it’s absolutely necessary, as it can use up a lot of your precious water supply. If possible, get to a place where you can refill your fresh water tank after bleeding the system.
How Do I Bleed Air from an RV Water Pump?
If there’s air trapped in your RV’s water pump, you’ll use the same simple method noted above to bleed the air from the pump.
- Turn on the water pump and let it run for a bit to allow the water in the system to pressurize.
- Turn on the faucet that is located furthest away from the water pump.
How to Bleed an RV Water Heater
If you’ve completed all of the above and you still have air in your RV’s water system, there’s a small chance that you may have air bubbles in your water heater.
Take the following steps to bleed your RV’s water heater:
- Turn OFF your RV’s water heater.
- Wait an hour or so to allow the water in the tank to cool down.
- Shut off the main water supply.
- Open a faucet inside your RV to relieve the pressure in the system.
- Flip the pressure relief valve on your water heater and allow any water to be released.
- Close the pressure relief valve.
- Close the open faucet inside the RV.
- Turn your main water supply back on and allow your hot water tank to fill.
- Once your hot water tank is full, turn the water heater back on.
How to Flush and Clean an RV Hot Water Tank
If you’d like to watch us flush and clean our Atwood hot water tank, watch these two videos. The first video will show you the entire method, and the second video will show you a surprise!
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Terry
Sunday 12th of October 2025
It trid getting air out my line by hooking up to city water that works good all line flow good but when I try using my pump for freashwater it's still sputtering
Lea
Friday 11th of July 2025
We full time in our Thor Four Winds class c, and recently every time we hook back into city water after travel (using water pump during travel time), there's air in the lines AND the fresh water tank overfills to the point it's leaking outside.
We've recently noticed a high pitched noise when we run the water as well?
Been traveling over two years and this is new. Working to resolve it, but maybe we're missing something simple.
Thanks
TheRVgeeks
Friday 11th of July 2025
Hi @Lea... sorry to hear about your problem. We're not 100% sure about the water system in a Thor Class C... unfortunately, there can be a lot of variability in how RV manufacturers plumb their systems, so we're going based on a bunch of assumptions. But, typically, your water pump would be the only connecting point between your onboard water system (i.e. fresh water tank) and the city water supply (which pressurizes the plumbing lines instead of having to use the pump). So the fact that you're having a problem with the fresh water tank overflowing when you're connected to the city water supply leads us to believe that the check valve/backflow-preventer that's built into the water pump may have failed (could have happened at a park with high water pressure if you weren't using a pressure regulator). That would allow the pressurized water from the city water supply to backflow THROUGH the water pump back into the fresh tank. And that COULD also explain the high pitched noise you hear.
Quick, easy, cheap fix would be to install a backflow preventer inline with the water pump. If you can find your pump, look for the inlet side (that's the side that would have the water line connected to the fresh water tank so the pump can draw water in to pressurize the system). You should be able to get a backflow preventer that would screw into the plumbing BETWEEN the pump and that line from the fresh water tank (would be something like this one: https://amzn.to/4kw4F9a but you'll want to confirm the size and style of the fitting to be sure it will just screw in... you might need other fittings to make that happen).
Just be sure to install the backflow preventer the correct way, as they are one-way valves. They always have an arrow on them, so you know which way it should be installed. In this case, the arrow will point toward the water pump... since the water should flow from the tank, through the valve, and to the pump.
Hope that helps!
John
Tuesday 25th of March 2025
I have a 2018 Kodiak 338BHLS. A full timer. I am on city water. As for our regular maintenance I changed out all my outside water hoses and water filter.
After this I have perfect water flow (H&C) to our outside kitchen our inside restroom and shower. So all water valves are working fine except for our kitchen island. Both H&C do not flow.
I have tried to open all valves and still nothing but a drizzle in our kitchen.
Also our water pump from our fresh water tank doesn’t pump water either.
TheRVgeeks
Wednesday 26th of March 2025
Hi John. Sounds like there's potentially two problems going on here:
(1) For the kitchen sink, it sounds like something may have plugged up the faucet plumbing. First, we'd suggest you remove and check the aerator at the output of the faucet. Debris from the system may have accumulated there, blocking the flow. If that doesn't solve/fix the issue, then the blockage COULD be further upstream. We've read that some brands/models of faucets have check valves built into them (to prevent water from backflowing into the plumbing) that can become clogged and/or can fail. You could test to see if that's the issue by disconnecting one/both of the water lines that connect to the faucet and see if water flows out (using a bucket or something else to catch the water from the disconnected line, of course). If water flows out of the line(s), the faucet is the culprit.
(2) The water pump issue sounds like there's a valve for winterizing that isn't in the correct position to allow the pump to supply water. Our guess would be a valve used to siphon RV water system antifreeze into the plumbing, which would be in the water line between the fresh water tank and the pump itself. It should have a hose attached to it OR a spot to attach the hose that gets inserted into the jug of antifreeze. It's likely in the wrong position, so the pump can't draw water from the tank to supply the house.
Hope these two ideas get the problem solved... or, at least, get you on the right track. Let us know how you make out.
Bob Post
Wednesday 25th of December 2024
I have been struggling for several days with air in the water system. I changed the pump and it made no difference. I pressurized the system with city water and bled everything to smooth flow. Switched back to pump and tank water to find it was still pushing air into the lines. The hot water tank is an Aqua Hot and all the water valves seem to be tight and set correctly. I am stumped and cannot get to the tank, it's buried in center of coach. The only thing I can think of is a hole somewhere but no leaks. No water leaking from the coach anywhere. Tank is still full. Where else can air be drawn in? Bob 2014 Entegra Aspire 42RBQ
TheRVgeeks
Saturday 28th of December 2024
Hey Bob... sorry to hear about your issue. Tracking these kinds of things down can be a real hassle. It sounds to us like there's a valve (water heater bypass, winterizing kit, or even the outdoor shower?) that's not in the correct (or completely open/closed) position. Did you just de-winterize the coach? If so, we'd take a good look at all valves you normally touch for that... and be sure they're set correctly for normal use. Another thing to check could be the plumbing in and around the city water/tank fill valve (assuming your Entegra has one like our old Newmar did). It's possible that the backflow preventer on the city water inlet isn't working correctly and is allowing air into the system. Or the valve itself could be bad, allowing the pump to draw air in from somewhere else in the plumbing system.
Check out this video about a similar problem we had with our city water/tank fill valve (not the same symptom... we didn't have air in the lines, but our water pump kept cycling, even though no water outlets were open)... maybe it will give you some ideas: https://youtu.be/MjyU2eClPcA
Ray Davis
Saturday 2nd of November 2024
Just a quick side note regarding the T & P Valve. Pressure relief. Scale can and does build up inside the safety device that at times will not allow the valve to fully reseat, resulting in a drip that just will not stop. Always good to have some teflon and a replacement of the appropriate size and model for the water heater. Cheap Insurance.