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Winterizing: Part 3 – Antifreeze In Fresh Water System

| Updated Nov 23, 2021

Note: Third of four parts. In Part 1 we drained the fresh water tank and the water heater. In Part 2 we bypassed the water heater.  Also, some blow out the plumbing with compressed air.  Roadtrek Corporation advises against doing this. In this part we look at the fresh water system.  And when it comes to Roadtreks, it seems there are as many suggested ways to winterize as there are Roadtrek models. While these how-to guides refer specifically to our 1995 Dodge Roadtrek 190 Popular, most of these tips will also apply to other models. If in doubt, check your manual for your specific RV.

Pour in 1 gallon of antifreeze 2
Pour 1 gallon into the fresh water fill

We are now ready for the antifreeze. We usually buy two gallons so we have extra for flushing during winter camping, but in a pinch you can winterize with one gallon. Remember if your water heater is not bypassed, you will need 6 extra gallons of antifreeze to fill it.  You need to get RV antifreeze, it is non-toxic and can be used in drinking water systems.  We prefer to get the stuff in the rectangular bottles – just because they fit between the toilet and the wall in the bathroom.  We use antifreeze for flushing during winter camping (we use only the black tank in the winter).

You will need a funnel to get the antifreeze into your empty fresh water tank through the gravity fill port.  In Roadtreks these are usually located in the passage side front door or the rear door.  Pour one whole gallon into the tank.  Depending on the number of faucets you may need more.  Too much is fine, but too little is a problem.  Now you are ready to run the antifreeze through the plumbing lines.

Run Cold until it turns pink
Run cold until it turns pink

Turn on your water pump.  If you have already dumped your black and gray tanks prior to winterizing, use a basin to catch any of the liquid at the faucets.  This is to avoid adding the heavily diluted antifreeze into the tanks.  Once it becomes bright pink, go ahead and let it go into your gray tank.

Run Hot until it turns pink
Run hot until it turns pink

Start with the kitchen sink.  You want to do one faucet at a time.  Turn on the cold water and run until it turns pink, then shut it off.  Then turn on the hot water until it runs pink and shut it off.

If you have a bathroom sink, you will not to do the same there.

Shower - Run hot & cold until both are pink
Shower – run hot and then cold until both are pink

Then do the shower.  Turn on the cold until it runs pink and then the same with the hot.  If you have an outside shower do the same there.  If you have already dumped you can run into a bucket or basin instead of the toilet.

Toilet - Flush until pink
Toilet – Flush until pink

Next flush the toilet until the water runs pink.

Now you have that “pink stuff” in almost all of your water lines.

Can you think of what we are missing?  They are probably the most commonly missed items in winterizing (besides the macerator on newer Roadtreks).

City Water Input - until pink
City water check valve

First is the city water input in the outside compartment.  It has a check valve in it.  Disconnect any quick release connector you might have added and reach a finger up inside to push on the check valve.  Some water will come out.  Keep pushing on it until the water coming out is pink.  If you forget this and it freezes it will require replacement of the valve and potentially other plumbing parts.

Fresh Water Drain - Runs PinkSecond is the fresh water drain line.  The drain line from the fresh water tank can up opened briefly until pink stuff runs out.  Then close it back up.  You should still have adequate antifreeze in your fresh water tank to protect it.

Oh yeah, be sure to turn off your water pump.

For Older Roadtreks only.

Low Point Drain Valve Open
Low point drain valves open

For those of you with older Roadtreks, you will not have an outside shower, but you may have low point drain valves (one hot, one cold) instead.  They are very handy for draining the system, but they need to be winterized too.  They are located near the city water connection (valve shown open in the photo).

Run Low Point Drains until Pink
Run low point drains until pink

The output of these low point drain valves is in the wheel well.  Should you not have a water heater you will only have one of these valve and drain lines.

Open each valve (hot and cold) until the output runs pink.

You have now run antifreeze through all of your fresh water system.  But you still have a few items left to do – dealing with your black and gray systems.  You are ready for Part 4.

Mike Wendland

Published on 2013-10-29

Mike Wendland is a multiple Emmy-award-winning Journalist, Podcaster, YouTuber, and Blogger, who has traveled with his wife, Jennifer, all over North America in an RV, sharing adventures and reviewing RV, Camping, Outdoor, Travel and Tech Gear for the past 12 years. They are leading industry experts in RV living and have written 18 travel books.

22 Responses to “Winterizing: Part 3 – Antifreeze In Fresh Water System”

November 16, 2014at3:00 am, Michelle Hand said:

Anti-freeze in fresh water systems? Couldn’t that make us or our dogs sick, even die?

November 16, 2014at3:10 pm, Roger and Lynn Brucker said:

Michelle, that is why you use RV anti-freeze (aka the pink stuff). It is not toxic. You do not want to use the kind of anti-freeze you put in your vehicle radiator. That could kill you or your dog. Still you will want to flush your fresh water tank when you de-winterize, but you want to do that anyway to removed anything growing in there.

November 15, 2014at10:06 am, Ron Soupy Sayles said:

Already winterized the camper. Stuff works good. Don’t forget to pour some in the drains too.

October 08, 2014at7:40 pm, George D Patterson said:

4th Winter Coming Up …

October 04, 2014at6:47 pm, Jan Jorgensen said:

I just found several RV antifreeze’s with propylene glycol- alcohol to keep fluid from freezing right?

October 04, 2014at6:46 pm, Jan Jorgensen said:

Where is part about bypassing water heater?

October 04, 2014at5:03 pm, Jan Jorgensen said:

ROADTREK advises not to use compressed air in pipes

October 05, 2014at10:52 am, Steve Yorks said:

I also blow my lines out to reduce the amount of anti freeze needed.

October 04, 2014at8:48 am, Darin Bjornson said:

I never use antifreeze in my water system as it takes forever to get the taste out and it can damage the water pump. I blow my system out using an air compressor, disconnect the connections at the water pump and leave all fixtures in the open position. I do pour antifreeze in my traps.

October 04, 2014at12:02 pm, Lynn said:


As mentioned at the beginning of the article, Roadtrek advises NEVER to blow out the water lines. We have done it in the past, and have a friend who has done it every year since buying their first Roadtrek in 1991. But you do have to be very careful about the pressure. Still Roadtrek says you can damage things – particularly the water pump. We have found that using antifreeze takes less time (and equipment) than blowing out the lines. True you need to drain the fresh water tank – but there is at most a half a gallon in there. And the process of sanitizing the water system has never failed to remove the taste. Some people add a winterizing kit to feed antifreeze directly into the water pump instead of putting it in the fresh water tank. Personally I’d like to get antifreeze into the line from the fresh water tank to the pump. As for damaging water pumps, I think blowing out the lines is more likely to cause damage (clearly Roadtrek believes that) than RV antifreeze that is supposed to go through RV water pumps.

October 04, 2014at7:51 am, Carl Muise said:

Double check the ingredients on your antifreeze….. Don’t skimp and save a dollar or two a gallon….. Use anti freeze that does not have alcohol in it…. That will damage your rubber seals and gaskets….. You will need to get at a dealer probably ….. Not wal mart or auto parts stores….

October 03, 2014at12:35 pm, KT Pieper Kucken said:

We use ours in the winter but still put in anti freeze. We just dry camp at a place with pit toilets. Cold buns but fun!

October 03, 2014at9:55 am, Steven Burton said:

Why use antifreeze. Just us your motorhome all winter.

August 28, 2014at10:43 pm, Lou Ann Blackwell Vaughn said:

Just blow lines out , pour antifreeze in drains and toilet. If no water in lines…can’t freeze.
We’ve always done this way….we live in Indiana so winters brutal here too!! 🙁

August 27, 2014at7:28 am, James Wilkinson said:

This will be my first year winterizing my Lance. I’ve always paid to have if done but it’s expensive. I’m a bit apprehensive about the challenge. After all, winter can be pretty nasty in Michigan.

August 26, 2014at12:53 pm, Joffre Perreault said:

Live in Florida. No need to winterize.

October 29, 2013at6:07 pm, Marty said:

I’m so glad you mentioned the city water. I completely forgot about that when I winterized last week.
Thanks very much : )

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