Saturday, December 3, 2022


Ask Dave: Winterizing the RV’s water system


Answers to questions about RV Repair and Maintenance from RV expert Dave Solberg, author of the RV Handbook and the managing editor of the RV Repair Club. This column appears Monday through Saturday in the RV Travel and RV Daily Tips newsletters. (Sign up for an email reminder for each new issue if you do not already receive one.) Today Dave discusses winterizing the RV’s water system.

Dear Dave,
There’s a lot of confusion over winterizing. What’s the true danger of damage from freezing pipes?
– Some just drain and blow out the water supply pipes with compressed air.
– Some add antifreeze to traps; others don’t because there’s room for water to expand in the trap.
– Some fill the water supply pipes with antifreeze after draining and/or blowing them out.

Homeowners are advised to allow faucets to drip during extremely cold weather so that pressure doesn’t build up in the pipes.

Pex is at low risk for damage from occasional freezing since it can expand a little.

It would seem that draining the system and leaving all the faucets and low point drains open would be sufficient per the “This Old House Video”.

I’m not sure about that so I also blow out the supply lines. I do it once, wait a day and do it again – in case a little water accumulated at some low point. But that seems like overkill.
(The low point drain in my Micro Minnie also drains most of the water out of my water heater.)

Filling the system with antifreeze and then rinsing it out in the spring seems like WAY WAY overkill, but that seems to be the most common practice.

What’s your opinion? —Irv

Dear Irv,
Great question and something that has been a huge topic of discussion since RVs first started having plumbing systems and heading into cold weather.

To determine the best winterizing method for your rig, it’s important to understand how the water system of your rig is designed. There are two basic systems that provide pressurized water to your faucets, shower, toilet, and other areas. One is called city water, which provides pressurized water from an outside source such as a campground faucet connected to the rig and runs through the plumbing system. The other is a fresh water tank that is filled and pressurized water is supplied by an onboard water pump.  Pressurized city water bypasses the water pump. However, after that, both systems utilize the same pipes throughout the coach.

As you indicated, there are two ways to winterize the water system: either run RV antifreeze throughout the system, or get rid of all the water by blowing it out with pressurized air.  Which method is better? It all depends on how you are using your rig. If it’s going to be stored for a long period of time, I prefer blowing out the water. Here are the two procedures and some basic “tipping points” for both.

RV antifreeze

First, drain the fresh water tank and open all the low point valves to drain all the water from the lines. Shut the valves and remove the drain plug from the water heater. If your water heater has a bypass valve, turn that to the bypass mode so you don’t need to put 6-10 gallons of RV antifreeze in your water heater. If you don’t have one… get one!

Next, close the valves and have enough RV antifreeze on hand to fill your water system.  This could be anywhere from a few gallons in your case with a Micro Minnie, to 12+ in bigger rigs. This is also why you do not want to waste 6-10 gallons filling a water heater. If you have a winterizing kit or option, you can simply insert the 1/4-inch tube into a gallon of RV antifreeze, turn on the water pump and open the faucet farthest from the pump until the pink starts to flow. Do this for all faucets, showers, toilet, and toilet sprayer.

This photo shows a service compartment with the water heater bypass and the winterizing tube. If your rig does not have a winterizing option to draw antifreeze from the jug, you will need to fill the fresh water tank with enough RV antifreeze to fill all the lines and use the onboard water pump.


With the lines filled with RV antifreeze, you can travel in and out of cold temperatures and use the toilet. You can winterize on the road without the need of an air compressor and you can reintroduce fresh water easily.


The expense of RV antifreeze.  Draining the RV antifreeze after storage. Not having a winterizing kit and needing to fill the fresh water tank.

Blowing the system out

Using an air compressor and a city water fill adapter, connect the air hose to the city water fill and adjust the pressure down to approximately 40 psi so you do not blow out the fittings and connections. Drain the fresh water tank and the water heater. Turn on the air compressor and open the faucet the farthest away from the city fill until air comes out.  Close the faucet and work your way back opening all faucets, shower, toilet and sprayer and don’t forget the outside shower. If you have an ice maker in the refrigerator, remove the filter that is typically under the sink and run the ice maker through a couple of cycles to get all the water out of the line and unit.

Run the water pump for a minute or so as you will still have water in the line, pump, and screen as the city water system bypasses this.


No water in the system and no expense.


Can’t use the system without reintroducing water throughout.

My Opinion

I personally like to blow the system out; however, I typically winterize and then put the unit in storage for the winter. We have taken a few trips to Colorado in the winter and just used a couple of gallons of water in the bathroom for the toilet. However, if you are going to be using the unit where temperatures will be in and out of the freezing range, the RV antifreeze is a better option as you can add water easily and probably do not have access to an air compressor on the road.

So both methods work and over the years I’ve learned that not everyone likes the same thing. The main idea is to keep the lines from freezing and bursting as well as the water heater. This can be an expensive repair. Plus, some owners feel more comfortable adding antifreeze because they feel all the lines are protected.

Check out the videos on RV Repair Club for both methods.

Read more from Dave here

Dave Solberg worked at Winnebago for 15 years developing the dealer training program, as marketing manager, and conducting shows. As the owner of Passport Media Creations, Dave has developed several RV dealer training programs, the RV Safety Training program for The Recreation Vehicle Safety and Education Foundation, and the accredited RV Driving Safety program being conducted at rallies and shows around the country. Dave is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club, a one-stop go-to online resource for RV enthusiasts. 


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Ray R
1 year ago

My preferred method is to take the RV south for the winter. Yes you need to run the furnace few nights. I’ve done this for 8 years now and have had no problems.

1 year ago

Don’t forget the black tank flush line, with either antifreeze or compressed air

1 year ago

A friend of mine filled his system with RV antifreeze, didn’t use it the next season and left the antifreeze for the second cold season. He ended up spending $8000 to replace his water system. Apparently the antifreeze is only good for one year.

1 year ago

I do both. I blow out the system after draining everything; remove the water heater plug, water pump screen and bowl, and water filter cartridge; and disconnect and drain the toilet foot pedal.
Then I add a small amount of antifreeze to all the p-traps, toilet bowl, and gray tank just in case there is any water left that didn’t drain. I normally use about 1/2 gallon of antifreeze each winter. And, since I always carry a 12v compressor in my RVs, I have winterized using this method in several campgrounds, and even a highway rest area, before returning to Denver after snowbirding south of I-10 (we have had snow at our house on Memorial Day!).

1 year ago

I used the pink antifreeze one year, and it took along time to get rid of the bad taste left in the lines. I blow out the lines now however, I do fill the traps with the pink.

James Starling
1 year ago
Reply to  Walt

Rinsing system out with fresh water before filling tank and lines?
Also, you can save and reuse some antifreeze with low point drains
At least reuse in traps and toilet bowl and Black tank.

Dick and Sandy near Buffalo, NY
1 year ago

Your method of winterizing can depend on the size and functions of your water system. I always use RV Antifreeze in our water system because it involves a full bath and a half, clothes washer, kitchen sinks and an ice maker. That means water lines for the shower, two toilets, two bath sinks, the washer, two kitchen sinks and the ice maker. There are way too many places where water lines are not accessible as they are installed before many cabinets and appliances are installed. The cost and time to put in a few gallons of RV Antifreeze to insure all my water lines and appliances that use water are winterized is better than trying to locate and repair any water line. Also, I save most of the RV Antifreeze that I drain out from my low water drains when I de-winterize as RV Antifreeze can be reused. I sleep better knowing my water system is fully winterized. Works for me.

Royce Hershberger
1 year ago

Used to blow mine out, but on my old Jayco I some how didn’t get a nautilus system valve blown out and it broke from freezing. Then couldn’t find the same valve to replace it with, so went back to the anti freeze no more problems.😀

1 year ago

The article mentions the disadvantage of the expense of RV antifreeze, but it’s really not much at all. After draining and by passing, I put six gallons of the pink stuff in and run the toilet and each faucet briefly, at least long enough to fill the p-traps. At $2 to $3 per gallon that’s not much of a serious maintenance expense. Less than $20 and peace of mind.

1 year ago
Reply to  Dan

The real advantage of using the antifreeze, even after blowing out the lines is it will lay in the low spots on the lines. Since you don’t know how the lines are run, the low point drains may or my not be at the actual lowest points and there could be some sags in the plumbing where the water will collect. The cost of the antifreeze is a lot less than a plumbing repair.
I also agree with installing a winterizing kit. Putting the anti freeze in the fresh water tank will leave some it laying in the bottom of the tank even after draining it. While it’s not harmful, you may be tasting it for quite a while.

1 year ago
Reply to  Bob

If the manufacturers would make the low points the actual low points, then all we’d have to do is open them and open all the faucets. But we all know they don’t……

Bob M
2 months ago
Reply to  Dan

The price of RV antifreeze depends on where you get it. Ace hardware has it on sale for 2, 1 gallon jugs for $8.00. An RV dealer in NY wants $8.99 a gallon.

Stephen Malochleb
1 year ago

I stopped using RV antifreeze years ago because I found that it attacked the orings in the faucets and toilet valve. I switched to the blow out method and have had no leak issues since. It may be just certain brands that cause this issue but got tired of changing seals.

1 year ago

Interesting…..After using the antifreeze method for years, my water heater bypass went bad. (2003 Horizon was electrical and the plumbing hard to get to behind the wet bay panel) I decided to just blow it out vs. filling up the 10 gallon tank. Issue was when I went to use it the next spring, I had three faucet gaskets that had dried out and cracked. Was a pain finding replacements. $30-$40 to fill up water heater was my future choice. (less than one night at a campsite these days)

Rock & Tina
1 year ago

Dave didn’t answer the questions asked.

1 year ago
Reply to  Dave Solberg

You also didn’t answer about the traps under the sinks.

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