Wednesday, February 1, 2023


RV Doctor: Quick Q & A on using RV antifreeze

Dear Gary,
I am winterizing my Hi-Lo and am wondering about putting RV antifreeze in the fresh water tank and pumping it through the system. That is what the book says to do, but I don’t know if that is safe. Can I pull off the pump inlet hose and put it directly into the jug of antifreeze and pump it through the lines? —Dave A.

Dear Dave,
You can absolutely pump the antifreeze throughout the system as you suggested, but it might be easier by pumping it backwards through a faucet spout. In fact, a backflow kit with a hand pump is available for that very purpose. You can find the kit at such places as Walmart,, RV parts stores and

But it is totally acceptable to pour the antifreeze directly into the fresh tank and use the RV’s water pump to pump it throughout the system as well. You can’t go wrong either way.

gary-736Read more from Gary Bunzer at the See Gary’s videos about RV repair and maintenance.




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Winterizing your RV this season? Amazon has a wide choice of RV antifreeze.


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3 years ago

Many people, many situations. None are correct for everyone, so I agree with.Gary.

I’m in the, “put 5 gallons of antifreeze into my fresh water tank and pump it throughout the system” camp.

I never drink from my holding tank for all the aforementioned reasons. Way to many things can grow in the tank. It’s for washing dishes and the occasional shower. And that’s only if the parks I go to shut off the water supply for who knows why. It’s just an emergency backup.

So, if you don’t boondock like I and many others NEVER do, there should be no reason to not put the antifreeze into the fresh water tank to fill the system with antifreeze. Easy peasy.

In the spring when you put the tank back into service just fill and drain a couple of times and you’re good to go.

3 years ago

There is a cheap winterizing kit (just a diverter valve) that lets your pump pull either from the fresh tank or a PVC tube you stick in the antifreeze jug… By FAR the easiest and best way to fill pipes with antifreeze. I blow mine out with air, and then pump in AF — done in a couple minutes, and uses less than a gallon each cycle on a 35′ trailer. Bypass the HWH and drain independently; do NOT fill the heater with AF. Drain the fresh tank by gravity.

Here’s a video if it helps you:

Charlie Burke
3 years ago

Gary, I am amazed that an industry professional would advocate putting RV antifreeze in a fresh water holding tank. Nearly if not all fresh tank drain from the side leaving ?gallons of water in the tank. Line 1 on most RV antifreeze is “do not dilute”. Many thanks are made using the spin molding process. This leaves a very rough surface to trap “stuff”. As Warren pointed out it is very difficult to remove the taste.

Warren Gress
3 years ago

Regarding pouring antifreeze into the fresh tank to winterize, it is very difficult to get that taste out of the tank. It’s better, and uses less antifreeze, to just draw it out of the jug by the water pump.

Mike Rodgers
3 years ago

I pump Anixter freeze through my system all the time. Connect a suction hose to the water pump. I pour 3 or 4 gallons of antifreeze into a 5 gallon bucket. Open all my faucets until it runs through including the washer and and the ice maker. I do not think it’s a good idea to put it in your freshwater tank.

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