How To Blow Out RV Water Lines With An Air Compressor

Whether it’s because you’re ready to winterize your RV or you simply want to flush your water pipes and start fresh, every RV owner should know how to blow out RV water lines properly. 

Of course, this is something that you can pay a professional to do for you.

You can even bring your RV into a local repair shop and have them blow out your water lines for you, but the process is actually rather simple.

So, there’s no reason to spend the extra money on this service when you can do it yourself. 

How To Blow Out RV Water Lines?

The best and safest way to blow out your RV water lines is to use an air compressor.

By blowing air through the lines at high pressure, you can ensure that there isn’t any water left in your lines before temperatures dip below freezing and the risk of pipes cracking or bursting goes up. 

That being said, there are several safety measures you should observe before simply hooking up your air compressor and blowing air through your water lines.

Plus, you’ll need to know exactly where to plug the compressor in and you’ll need to consider where the water left in your RV’s water pipes will drain when you start the compressor. 

Here’s a step-by-step breakdown of how to blow out RV water lines with an air compressor:

  • Disconnect gas and electricity from your RV water heater
  • Open all faucets and drain toilet
  • Drain all holding tanks (fresh, grey, and black water)
  • Disconnect any aftermarket water filtration systems
  • Screw blowout plug into the exterior water inlet
  • Attach an air compressor to blowout plug
  • Set air compressor to the optimum pressure setting
  • Turn on compressor
  • Open valves to drain water lines one-by-one
  • Turn off the air compressor and disconnect the blowout plug
  • Finish winterizing by adding RV antifreeze

Steps To Blowing Out RV Water Lines

While the steps listed above will help you blow out your RV’s water lines, there are several nuances to each step that need to be considered to do so safely.

So let’s run down these steps and break them down further!

Step 1: Safety First!

disconnect the gas and electricity to your water heater in rv

Safety should come first when we’re discussing any sort of RV maintenance.

So, before doing anything else, make sure you head out to your RV and disconnect the gas and electricity to your water heater at least 24 hours before you plan on blowing out your water lines. 

Blowing out your water lines while they still contain hot water can result in burns and other damage to the external components of your RV.

That’s why we recommend turning off your water heater and allowing any water in your lines to cool for a day before you proceed. 

If you’re on a time crunch, however, you can accelerate the process by turning off the water heater and opening all of the hot water faucets inside your RV.

When the water begins to come out cool, it will be safer for you to start draining your lines. Just make sure that you don’t overflow your grey water tank during this initial step!

Step 2: Drain Tanks and Unplug Connections

RV holding tanks Drain

Before you even worry about connecting your air compressor, you’ll need to do some prep work.

Start by draining all three of your RV’s holding tanks, including freshwater, greywater, and black water.

For the latter two, you should connect a sewer hose and proceed as if you’re dumping your RV at a standard campground dump station. 

Many freshwater tanks have a manual clear out that allows you to drain the tank directly out of the bottom.

Use this to save yourself time instead of running your water pump to pull all the water out of your freshwater tank and into your grey or black water holding tanks. 

If you have an inline water filter or another type of RV water filtration system hooked up, you should also disconnect it before continuing.

From there, you should also make sure to remove any water that may be leftover inside your RV water heater or the associated water lines.

Finally, open all of the hot and cold faucets in all of your sinks to make sure that any excess water drains through and out of your holding tanks. 

Step 3: Locate Blowout Plug

Locate Blowout Plug

Your RV’s blowout plug is an accessory that connects to the water inlet either on the side of your rig or in the underneath storage compartment.

In many RVs, this water inlet will be labeled as the ‘city water connection’. And your blowout plug will typically be made of sturdy plastic material, but some RVs come with blowout plugs that are made of stainless steel with a corrosion-resistant finish. 

Attempting to blow out your RV’s water lines without a blowout plug can result in damage to the lines themselves.

So this is a very important accessory to locate and connect to your RV’s exterior water intake before hooking the other end up to an air compressor.

If you can’t seem to locate the blowout plug that came with your RV, check out this heavy-duty model from Camco

Step 4: Connect Blowout Plug and Air Compressor

Connect Blowout Plug and Air Compressor

Next, you’ll need to screw your blowout plug into your RV’s exterior water inlet.

Once you have screwed in the blowout plug tightly, you can connect the air hose from your compressor to the other side of the blowout plug.

If you need a recommendation for a quality air compressor, check out our article on the best RV air compressor!

These compressors are super useful for keeping your RV tires inflated when you’re off-roading, but they are also perfect for blowing out your RV water lines.

Just make sure to preset the PSI on your air compressor between 30 and 40 PSI to ensure that you don’t damage your lines by using too much pressure. 

Step 5: Blow Out Your RV Water Lines!

Now, you’re pretty much ready to turn on your compressor and blow strong air through your water lines.

As you do, make sure that you open up the valves to your specific water lines one at a time so that you blow each out completely.

Once you’ve finished blowing out one line, close the valve and then move on to the next. 

Remember that most RVs have at least two water lines for hot and cold water. But many also have separate lines that run through their water heaters.

So you’ll need to make sure to locate and open all valves in order to completely drain all water out of your rig. 

As you might imagine, we recommend locating all of the valves for your water lines before you reach the step of turning on your compressor.

This will help you maximize your efficiency when you do flip your compressor on and it will also help you avoid damaging your lines by accidentally closing a valve when you’re hoping to keep it open! 

Step 6: Disconnect Compressor and Blowout Plug

Once you can observe no more water exiting your RV’s holding tanks, you can turn off your air compressor and disconnect it from your blowout plug.

Because you may need access to your RV’s exterior water inlet for more winterization steps, you can also remove the blowout plug at this point.

Just be sure to store it in a safe, secure location because this RV accessory can be easy to misplace because of its small size. 

Step 7: Bypass Water Heater

Most RV water heaters use about six gallons of water at a time. But there’s really no reason that you need to pass antifreeze through the water heater and its lines if you’ve done a complete job of blowing out your RV water lines.

So, before you proceed to add antifreeze, you’ll want to install a bypass line to reduce the amount of antifreeze you need to use for the next steps. 

Step 8: Add RV Antifreeze

Antifreeze is a solution that has a much lower freezing point than plain-old water. That’s why many RV owners use it as a further fail-safe against cracked or broken water pipes.

Even if you’re not able to blow 100% of the water out of your lines using the process we’ve outlined above, the antifreeze will mix with the remaining water to lower the freezing point of the entire solution and further protect your water lines. 

That being said, this will also dilute your RV antifreeze solution and, in some cases, could make it less effective.

So, only after you’re confident that you’ve blown as much water as possible out of your lines, you can close the outlets to your RV’s holding tanks and add about 1-3 gallons of RV antifreeze solution. 

There are several ways you can add antifreeze to your RV’s water system if you’ve never done it before.

Most people, however, avoid pouring antifreeze directly into their freshwater holding tank because it will require you to use more antifreeze in order to run it through all of your water lines. 

Instead, most RVers use a hand pump to add antifreeze directly into their water lines through the exterior water inlet.

Some also purchase a more expensive water pump converter kit that essentially installs a bypass hose to the inlet side of the water pump in order to pull antifreeze directly from the bottle. 

Step 9: Turn On RV Water Pump

Whichever method you choose to add antifreeze to your water lines, your next step is to run your RV water pump for several seconds to pull that antifreeze solution through all of your water lines.

To make sure this process has proceeded completely, open all of your RV faucets until you see antifreeze flowing out. 

Also, you should open and flush your RV toilet until you see the antifreeze flowing into the bowl.

From here, you can turn off your RV water pump and then pour an additional quart of antifreeze into your sink drains and toilet in order to adequately fill the traps and keep them from freezing.

How Much PSI Do I Need To Blow Out My RV Water Lines?

Most RV manufacturers recommend setting your air compressor between 30 and 40 PSI to blow out RV water lines. This provides enough pressure to force all the remaining water out of your lines without risking damage to the lines themselves.

In addition to this recommended PSI range, most RV owners like to use an air compressor with a minimum capacity of ten gallons to blow out RV water lines.

This capacity is more likely to provide enough air to completely clear out your water lines without leaving anything leftover. 

Why Do I Need To Blow Out My RV Water Lines?

If you store your RV in a location where temperatures dip below freezing at any point, it’s recommended that you blow out your water lines before placing your rig in storage.

This is because even a small amount of water left in your pipes will expand as it freezes, and this expansion can cause your lines themselves to crack or break entirely. 

When you leave your RV in storage for months at a time you can then open it up for the summer and realize (usually the hard way!) that a more extensive repair to your entire water line system is needed.

To avoid this, you’ll need to purchase an air compressor and use it to blow all the water out of your lines before placing your rig in storage. 

While some of the best RV air compressors aren’t overly affordable, their cost is much less than you’ll inherit if the lines in your RV break.

So, in the interest of preventing larger RV damage that results from your own negligence, you’ll need to blow out your RV water lines before temperatures dip below freezing in your area. 

Conclusion

If you follow the steps we’ve outlined, we’re confident that you’ll be able to blow out your RV’s water pipes with minimal effort.

And if you want to maintain the integrity of your water lines throughout the winter season, blowing all moisture out of your water pipes is an essential step to properly winterizing your RV. 

While this process takes a little bit of time, most of these steps simply require you to open a valve and allow gravity to do the work for you.

So, the good news is that you can perform the initial steps for blowing out your RV’s water lines while you’re also winterizing other parts of your home or property. 

We hope that our simple steps above have helped to give you an easy-to-follow process for how to blow out RV water lines.

And, as the seasons shift, we hope you use your downtime to plan next season’s RV road trip itinerary!

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