Saturday, May 27, 2023


Ask Dave: Can we just open RV’s drain valves to winterize?

Dear Dave,
Our RV will be stored in Myrtle Beach, South Carolina, for the winter. It has several low-point water drain valves that drain most of the water out. Do you think we still need to have it winterized to be on the safe side? I really enjoy your column; I read it every week. Thanks for any help. —Winfred, 2019 Jayco White Hawk 32KBS

Dear Winfred,
You will need to do more than just open the low-point drain valves. This will drain the tanks and lines coming from the tank or tanks. However, those drain valves do not drain the lines going to the faucets, showers and toilet completely as the closed faucets will still hold a slight vacuum and keep water in. Plus, the onboard water pump will have water in the lines to and from, as well as inside the diaphragm. And don’t forget about the water line going to the ice maker in the refrigerator, if you have one.

Ways to winterize

There are two ways to winterize: blowing all the water out with an air compressor or running RV antifreeze through the system. In either case, you will want to drain the water heater by removing the drain plug. If you have a Suburban water heater, it will have an anode rod. You will want to verify that it is not corroded and need to be replaced.

This is also a good time to flush out the bottom of the tank. The drain plug sits about 2” above the bottom of the tank, so you do not get all the water and sediment out. It’s not enough to cause an issue if frozen, as there is enough space in the tank for the water to freeze and expand. However, it sits there forever and gets skunky. I’ve been shooting video content on a 2015 Thor Challenger and the water tanks smell like the black water tank. There are flush wands designed to attach to a garden hose so you just insert it and flush out the tank until it runs clear.

I will do this first and then add 1/4 cup of bleach to a gallon of water and run it inside and let it sit for a day and then reflush. If it still is smelly, I will make a larger solution and either pump it through the fresh water tank or remove the pressure release valve on the top of the tank and fill it there.

Water heater bypass valve

You should also have a water heater bypass valve. It is typically on the incoming water line to the tank. Turning this valve isolates the water heater so you do not have to fill 6-10 gallons of RV antifreeze in the tank. This also allows you to blow out the lines without running through the tank if you are using compressed air.

Winterizing with RV antifreeze

You should have a winterizing valve that allows you to use the onboard water pump to draw RV antifreeze into the system through a tube. If not, you will need to add several gallons of RV antifreeze into the fresh water tank and draw it through the system with the onboard pump.

If you have an ice maker, shut off the water valve, typically under the sink with a filter, and remove the filter. Most refrigerator manufacturers recommend running the icemaker through enough “cycles” to get the water out of the lines and tray. Turn on the pump and go inside and open the faucet the farthest away from the pump until the pink stuff comes out. Work your way back and don’t forget the toilet and sprayer on both your inside and outside shower. I even open the icemaker water valve and run water into a bucket under the sink until it turns pink.

Winterizing with air

This is the method I typically use, as the unit is going into hibernation for about 6 months, so I don’t need to use any of the functions. I developed this handy connector that screws into the city water fill valve and has an air chuck on the other end so I can winterize it myself without needing someone to hold the air hose on the screw-in valve. Turn the compressor down to 40 psi, as most compressors will be over 100 psi and will most likely burst a pipe or fitting.

As with the RV antifreeze method, start with the farthest faucet and open until air comes out. You will want to run the onboard water pump to get any water out of the incoming line, pump itself, and outgoing line, then blow that out. After all the water is out, dump a small amount of RV antifreeze down any sink that would have a “P” trap underneath, as that will have a small amount of water.

Lippert has developed a small portable air compressor system called Floë, which is a very convenient method using compressed air to drain the lines at the touch of a button.

It is permanently mounted somewhere on the rig and plumbed into supply lines. It is available with either 12-volt power or there’s a 120-volt AC version. If you are traveling in and out of cold weather areas, this is an excellent method to winterize quickly.

 You might also enjoy this from Dave 

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.
– And some fill the water supply pipes with antifreeze after draining and/or blowing them out.

Continue reading Irv’s question and Dave’s answer here

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

Read more from Dave here


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Dave Solberg
Dave Solberg
Dave Solberg 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. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


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Bob p
5 months ago

In the first situation 100W heater for winterizing is about as much good as peeing into a hurricane. Example: hold your hand next to a 100W light bulb, you can probably get your hand within several inches before it gets even warm. I have lived from northern IL to FL and have always blown out the lines. The secret is connect the air compressor to continuously blow 40psi air until all the water is out, you can’t just shoot some air into a faucet and think you’ve cleared the water out. Also I blow the water out of the p traps and pour several ounces of antifreeze down the drain ensuring no water is in the drain to weaken the antifreeze solution. It’s worked since 1978 and never had a frozen line or drain.

Roger Marble
7 months ago

A couple areas I seldom hear mentioned is the “city water” to holding tank line and holding tank to water pump line. I have a short piece of hose I connect to the outside water connection. I pour maybe 1/2 cup antifreeze into the hose then add air pressure to ensure the back-flow valve opens and this treats the line and fittings inside the RV it only puts a small amount in the holding tank.

The suction side of the water tank to the pump can also hold water even after draining the holding tank so you need to be sure to “blow out the line from the water pump back to the holding tank. All of the above is done while I leave the holding tank low point drain open.

Steve Hericks
7 months ago

Your focus was entirely on treating water supply lines but there is another necessary point on water drains……traps in sinks and showers hold water and will break the trap if water remains. The easiest method is to pour a little antifreeze down the drain.

7 months ago
Reply to  Steve Hericks

Dave mentioned that

Bob p
5 months ago
Reply to  James

He may be a speed reader and sped right over that point. Lol

7 months ago

Does it get below freezing very much in Mrytle Beach?

Bob p
5 months ago
Reply to  Drew

Personally I have no experience with Myrtle Beach, however I live in central FL and this past weekend we saw below freezing temperatures 4 nights in a row. Looking at a map of the U.S. I see Myrtle Beach is north of central FL so I would surmise it got colder there.

7 months ago

I blowout all my lines, add antifreeze and then blow them out again so the antifreeze is not sitting in the lines. I also make sure my waste tanks are empty and after emptying them I dump about a 1/2-3/4 gallon of antifreeze in each tank and briefly pull each handle to get antifreeze around all areas of the valve. If you have a washing machine make sure you run it through a cycle to purge water out and dump a 1/2 gallon of antifreeze in the drum and then push the drain button to get it into the pump. RV Antifreeze is going for $4.00 a gallon in my area so it’s a cheap alternative then fixing a problem in the spring.

7 months ago
Reply to  Joe

Joe, great point on washers as they are hardly ever mentioned in the articles. Same with dishwashers, which aren’t as common but are out there in rigs.

I actually run my washing machine twice…one time each on hot and cold to be sure the incoming lines are completely winterized. I just start a cycle letting perhaps a half gallon of pink juice in, then cancel so the machine purges it. This ensures all incoming lines, internals in the washer, and outgoing drains are winterized.

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