An Informative Guide on How to Blow Out RV Water Lines

One of the best benefits of camping in an RV is the availability of fresh, hot water at all times. The better you upkeep the plumbing system, the better it will work.

In this guide, we’ll go over how to blow out RV water lines, why it’s important, and how to maintain your efforts. 

What Water Lines Are Used in RVs?

how to blow out rv water lines

There are essentially two types of water lines available for use in RVs:

  • Copper water lines
  • PEX or plastic water lines

Copper water lines are mostly found in older RV models. They are primarily used because the supply lines are easy to manufacture. Also, they are environmentally friendly — they don’t leave a large carbon footprint and can be recycled.

However, copper plumbing is rigid and does not fit into compact spaces. Also, it does not do well with water acidity, which means if you’re supplying water from a well nearby, the copper lines could split.

As the risks of copper plumbing outweighed the benefits, manufacturers started producing a new water line called PEX. It’s made up of two plastic tubes connected with a metal fitting, and it’s flexible enough to fit into any shape.

Also, the ABS plastic used in the PEX RV plumbing system is exceptionally durable and lasts for up to 15 years. It is lightweight too, so no level of acidity in the water can ruin the material.

PEX tubing is available in every hardware store, and it is generally recommended to keep some on hand for emergency situations.

Why Do You Need to Blow Out Water Lines in an RV?

Also known as winterizing the RV, blowing out water lines is an essential part of upkeeping your vehicle so that it is ready for travel all year round. Here are a few benefits of blowing out water lines in an RV:

Prevents Frozen Water Lines

Winterization, i.e blowing out water lines and ducts, prevents those parts from freezing when temperatures fall below 30°F. This protects the plumbing system from splitting and causing a leak. Exposure to water can also cause metal tubing to rust and leave a musty smell in the RV.

Cuts Down on Repair Costs

Properly blowing out the water lines prevents damage to the plumbing system. This helps you budget for luxuries or extra expenditures related to the RV. In fact, it is cheaper to winterize the RV (even professionally) than it is to get the whole plumbing system repaired only because it froze in storage.


Depending on how well you winterize your RV, the antifreeze procedure can keep the water lines from freezing for over 3 months, and for some parts of the RV, it can last for more than two winters. It is durable and easy to do by yourself. 

How to Blow Out RV Water Lines

There are essentially two methods you can follow to blow out RV water lines:

  • An air compressor
  • Antifreeze

Here’s the complete guide on how to blow out RV water lines using both an air compressor and antifreeze.

1. Turn Off Power

First, switch off all electric-powered motors and gas lines at least 24 hours before scheduling an RV winterization session. Also, unplug filtration systems.

2. Let Gravity Remove Water

Open up the sink, shower, and toilet drains so excess water is drawn out with the help of gravity.

3. Drain Residual Water

Connect a garden hose to a tank outlet and drain the RV black tank, grey tank, and even the freshwater tank. There shouldn’t be a drop of water left.

4. Attach a Blowout Plug

Connect a blowout plug to the specific inlet available in the RV. It’ll either be on the side where the black tank outlet is or in the underbelly of the RV.

5. Bring in the Air Compressor

Join the other end of the blowout plug to the air compressor hose and adjust the pressure between 30 psi and 40 psi. 

6. Switch on the Valves

Turn on the air compressor and, one by one, open up all the water lines including the holding tank outlets and blow air through them. Make sure to dry out all valves including lines running from the water heater so nothing is left that could freeze.

7. Unplug the Air Compressor

When the water lines have been completely blown out, i.e no water is left in any of the valves, turn off the air compressor and remove the blowout plug.

8. Coat with Antifreeze

Double check if the water lines have been completely dried off, then pour at most three gallons of antifreeze solution to eliminate any risk of plumbing damage.

Advantages of Using an Air Compressor to Blow Out RV Water Lines

Generally, an air compressor is highly recommended by experts when blowing out RV water lines. This is essentially because any contact with water can dilute antifreeze solutions and cause them to become fairly or completely ineffective.

Here are a few other benefits of using an air compressor to blow out RV water lines:

Efficient Method

Using an air compressor to blow out water lines is easier because you only need the mechanical device and some general knowledge of all the water valves present in the RV.

Eliminates the Use of Antifreeze

When winterizing with an air compressor, antifreeze is just used as a fail-safe tool to keep the toilet and washing machine tubes from freezing in the winter. Other than that, it isn’t really required. This also helps you save more money because you don’t use as much antifreeze. 

Does Not Leave an Aftertaste

To ensure the antifreeze method works, you’ll need at least 10 to 15 gallons of solution, which will inevitably leave a strong aftertaste along with a musty smell in the air of the RV. In contrast, with an air compressor, there is no lingering taste as all it does is blow air through the pipes.

How to Maintain RV Water Lines

Since water lines are a primary tool of water supply, it is important to optimize them. Some ways you could do this include:

Regulate the Water Pressure

Water lines are flexible and durable but thin, meaning high water pressure can easily split the line and cause a leak. Invest in an RV water pressure regulator to prevent this from happening.

Sanitize the Water Lines

Most RVers recommend using bleach to sanitize the RV water lines and keep them fresh and free of all obstructions.

Install a Water Plumbing Filter

As the name suggests, an RV water line filter strains out clogs and dissipates pungent odors to keep the environment pleasant.

Frequently Asked Questions

What happens if you don’t winterize an RV?

If an RV isn’t properly winterized, water will freeze in the pipelines which will cause them to split and leak water. You could spray a good amount of antifreeze if the RV is going to stay in storage when temperatures fall below 30°F. If you’re going to be traveling, use an air compressor to remove water so there’s no lingering taste of antifreeze.

Is an air compressor better than antifreeze to blow out RV water lines?

It depends on the RV you have — some work better with an air compressor and some need a heavier spray of antifreeze to flush down the buildup in the water pipes. Using an air compressor is the easiest and safest method to blow out water lines. Plus, it doesn’t leave an odor like antifreeze does.

Does antifreeze hurt RV water lines?

No, antifreeze does not hurt an RV’s water lines as long as it is specifically targeted at an RV’s plumbing system. It’ll keep residual water from freezing in the water pipes and splitting the line. However, regular automotive antifreeze can harm the septic system of an RV.

What type of air compressor do I need to winterize my RV?

Generally, most RV campers employ a hybrid winterization method in which they first open the faucets, pipes, and low-point drains so water runs out via gravity and then use a 2 to 3-gallon air compressor to remove any residual water. This cuts down on the manual work and removes the risk of water buildup in the pipelines.

What happens if RV water lines freeze?

When water lines in an RV freeze, they split and leak water inside the RV. It can be a mess to clean up, especially if there is a limited supply of cleaning rags, toilet paper, or even newspapers that would easily soak up the water.

Brief Summary

With all this knowledge on how to blow out RV water lines, you can now enjoy a steady stream of hot water in winter and clean water in the pipelines all year round!


Beau is an electrical engineer with a knack for DIY repair and construction. When he's not tinkering with his projects he's on the road travelling and enjoying an exciting lifestyle with his young family.

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