How to Blow Out RV Water Lines With Air Compressor

At the end of camping season, most people are ready to park their RV’s for the next season. While many people do still travel in the winter, it is a good habit to winterize your RV before the weather turns frosty.

This will help you keep your RV in good working order and prepare it for winter storage or winter travel depending on your preferences. Blowing out the water lines is one of the main tasks to be completed during your winterization routine, using a compressor to do it will make things simpler and quicker at the same time.

You can take your RV to a motor home repair shop or an RV maintenance center to have it winterized for you. However, if you have the tools and want to save both time and money, you can do it yourself at home. Using compression to blow out the lines is a simple way to winterize the pipe on your own. You can also use antifreeze as well to prepare your RV for the winter months.

To keep the plumbing working properly during the winter season, the plumbing system will need to have preventative maintenance performed. Blowing out the water lines, checking the gauges, and even changing the tires are all important tasks to tackle before the winter rolls around. 

If you want to avoid high repair bills and get your RV ready for winter, we have put together a helpful guide that will walk you through blowing out the water lines ahead of the cold season.

Motorhome in the winter

Why Do I Need to Blow Out RV Water Lines?

Before thinking about just how to go about winterizing your water lines by blowing them out, it is important to understand why it’s needed. When water is left in pipes and faucets during cold weather, it can freeze. While this is normal, frozen water in the pipes, faucets, drains, and water lines can cause cracking or other damage to your RV.

In addition to the water lines, standing water in the water tank can expand when it freezes which can lead to a water tank rupture. Replacing a tank is not cheap, and learning that you need to replace your tank a few days before your trip in the warmer months can put you behind schedule.

Not only are these types of issues costly to repair, but it is also often hard to pin down exactly what pipe or faucet is broken once the warmer weather runs around.

Air or Antifreeze for Winterizing RV Water Lines?

Winterizing an RV water system with compressed air is best suited if you live in an area with mild winters.

You’ll need blowout plugs  which are made of plastic or stainless steel and can be connected to the water inlet on your RV. This will help you to get rid of extra water from the pipes efficiently.

The plugs are attached to the water intake on the outside of the RV, which is then connected with an air compressor. A strong gust of air will blow out any excess water leaving your lines clear and dry thus protecting them from winter freezing. Using blowout plugs paired with compressed air to clear out your water lines makes winterizing simple and affordable.

It is also possible to use antifreeze to winterize the waterlines in your RV. This will help keep your waterlines safe even when there is no water present. This option takes a bit more work ahead of the winter and when you take your RV out of storage.

If you live in an area that has a lot of snow or long periods of freezing weather, it is worth using antifreeze to winterize your lines for maximum protection.

Both methods require a blow out plug and an air compressor. 

What PSI do I Need to Get Air Out of Water Lines?

Using the right air pressure when blowing out your RV water lines will ensure your pipes are ready for the winter and that you avoid damage. 

An ideal PSI is between 30-40, but no higher.

This will ensure that you have enough pressure to blow out stagnant water but that it is also gentle enough to prevent damaging your lines.

How To Blow Out Water Lines in RV With Air Compressor

You’ll need:

  • Blow out plug that connects to the city water inlet on your RV. 
  • Air compressor to blow out standing water from the RV water lines. A ten-gallon air compressor is usually sufficient to handle all sizes of RV.

Step 1 – Drain The Tanks & Water Lines

  • Turn off your water heater at least a day before you plan to winterize your RV.
  • Open the freshwater tanks and the reserve tanks on your RV to allow the water to drain.
  • Next, drain the grey and the black water tanks via the valve switches, which are usually located next to the fresh water tank valve. The black and grey tanks will need to be connected to a sew hose for draining while the fresh water tank can be drained on the grass.
  • Make sure the water supply is disconnected and also turn off the water pump after allowing the water to drain out of all of the valves.
  • On your water heater, open the pressure release valve or switch, remove the plug, and allow all the water to drain out. (If there is sediment in the tank, simply insert a hose to get rid of the sediment as the water drains.)
  • Turn on all the faucets in your RV to drain the water making sure you run both the hot and the cold water. Run the shower and tub faucet as well.

Step 2 – Setting Up Your Air Compressor

The size air compressor you use should be large enough to accommodate the size of your RV. A smaller RV can make do with a 2-gallon compressor, while a large one will need as much as 10 gallons. Make sure the pressure is adjustable so that you can ensure that it stays between 30 and 40 PSI for safety.

  • Put a blowout plug on the freshwater inlet and make sure it’s locked into place.
  • Once attached, set the PSI and allow the air to fill up for about 2 minutes.

Step 3 – Blow Out Excess Water

  • Start by closing all but one valve on the outlet.
  • Use the air compressor to blow two 15 second shots of air to clear the line. 
  • Close the line and move onto the next line.
  • Repeat the process until you have cleared all lines of water.

Make sure you make a checklist to avoid missing any water lines. You will need to flush the showerhead, toilet, and faucets on your RV. For hot and cold lines that run separately, make sure that you flush each line separately as well.

If you have outdoor showers or any other water lines, make sure to flush them with compressed air as part of the process.

Optional : Pour 1 c. of antifreeze into each fixture (sink and shower drains, and the toilet)  to get all water out of your plumbing system. Do this step after you’ve turned off your air compressor. 

Blowing Out RV Water Lines With Antifreeze

You’ll need:

  • Antifreeze designed for RV potable water systems (i.e. non-toxic and safe for use in drinking water systems). Camco Kit is one of the top sellers on the market RecPro is also a good choice for those looking for an eco-friendly option.
  • A bypass jug and kit for your water heater is also needed when using antifreeze for winterization.
  • Blow out plug
  • Air compressor

To blow out the water lines on your RV with antifreeze, there are few simple steps to follow.

  1. Start by removing all your inline bypass and water filters and then drain all of your water tanks. Drain water from your waterlines and even your water heater. You will need to turn on the faucets in your RV to drain out the water that may be lurking inside.
  2. Using a blowout plug, insert it into the intake value while connecting it to the air compressor. A PSI that falls between 30 and 40 is ideal.
  3. Open your valves one at a time and use the compressed air to blow out extra water, and then close the value again. Once you clear out all of your water lines with air, you can move onto the antifreeze portion of your RV winterization.
  4. Make sure you have your antifreeze on hand, one that is suitable for RV’s and also not toxic is best.  Pour the RV-specific antifreeze into the tank of the toilet and each drain in your RV.
  5. If you want to limit how much antifreeze is going into your waterlines, you can use a bypass line to the water heater. You will need to turn on the water pump to help pull the antifreeze into your system, make sure to open the valves in your RV to ensure a smooth flow. 

Final Word on Winterizing an RV Water System

Winterizing your RV is the best way to prevent it from suffering damage while in winter storage. In addition to cleaning your RV and making sure the engine is properly maintained, you will also need to winterize the water lines. This will keep the pipes, lines, and tanks from cracking or bursting regardless of how cold it may get outside. 

Also, make sure to park your RV camper in a covered storage area or a garage during the colder months to protect the exterior and other parts from weather damage. With our guide and a bit of time, you can protect your RV water lines for the winter affordably.

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