Potable Antifreeze question

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Well-known member
May 21, 2011
Hey all,

  We just were on a trip where we had to park our RV for 4 days in below-freezing temps.  Got down to 1 Degree F. on two nights.  I used potable antifreeze and filled all the lines (from putting the  antifreeze in the fresh water tank) and even the water heater.  I now know the water heater was a mistake, but didn't at the time.

  What do you have to do to flush everything?  I cycled several full tanks of the fresh water tank, flushed the lines, ran probably 30 gallons through our 6 gallon water heater.  Is that enough?  Is there something else I should do?  I can't taste it in the water now...

Next time we go on a trip, I will fill the tanks & lines with bleach mixture, and flush the tank again before filling the final time...  Am I good?

I used 2 brands of antifreeze from WM, BOTH brands said they are intended for RV/ boat drinking water systems (1 was Prestone, the other said it was rated as "generally safe" to drink by the FDA).  Looked like they were both mostly alcohol and propolene glycol.

Thanks for your advice!
There are 3 reasons I support the DRY method (Blow the lines out with an air compressor, several times) over the pink stuff method.  You now know the biggest one.

Do a normal spring time sanatization (Bleach 1/4 cup to 15 gallons of water, pump through all the lines, then drain, flush with fresh water, then drain re-fill adding a cup to a pound of baking soda to the water, then drain, and refill and flush one mroe time, then drain and re-fill and use).

Propylene glycol is safe to place in your fresh water lines. It is a good idea to have an inline fill line so you don't have to put several gallons of the solution into the fresh water tank in order to pump antifreeze into your water lines. If you can not drain all of the water out of the freshwater tank it would be advisable to add a small amount of antifreeze to the fresh water tank in order to keep that tank from freezing. Your hot water tank should have a by-pass to the water lines that lead into and out of the tank. Drain the hot water tank (After the hot water tank has drained I run a small amount of antifreeze through the fill line, close that line and then open the by-pass valve and back flush the return line and then close the return line) then close the fill and return lines and open the by-pass line. Run enough of antifreeze through all lines (Both hot & cold) until pink solution  is seen coming from all lines. Don't forget the commode and outside shower. I then drain the water out of the black & gray tanks and run/pour some antifreeze into each drain trap. If you have a washer don't forget about those water lines and drains. I an sure that I have forgotten something, but I am sure that some of our readers will fill those in for me.

Propylene glycol is safe, but one should not drink a large amount of the solution and it has a somewhat soapy feel. A solution of two tablespoonsful of Clorox per gallon of water is a good disinfect for your fresh water tank and water lines. Clorox can react with other compounds so I would not used a Clorox solution until the propylene glycol was flushed out of the water lines. 


Here I am living on Alabama and I am talking about winterizing a motorhome. I should defer to someone from Detroit. I just did not have enough faith that I had all the water blown out of the lines. I will have to give it another try.

Frank Hurst said:

Here I am living on Alabama and I am talking about winterizing a motorhome. I should defer to someone from Detroit. I just did not have enough faith that I had all the water blown out of the lines. I will have to give it another try.


Being a Michigander also (Grand Rapids area), I can also push the compressed air method.  I do not use that method anymore.  I know what I need to do for my TT and can do it in half the time to Winterize. 
Two gallons of RV antif-freeze and a protocol.  Good to go for the Winter.  No problems for many years.

Do what is comfortable and effective for you. 
Thanks guys!

1 last question on this topic (more for my spring tank cleaning protocol):

When you say "fill and drain" do you mean run all faucets until your fresh water tanks is empty?  Probably just ignorance, but I always run the faucets for 5 min, then stop for 5...  Do I need to do this?  I.e. is it possible to overheat or wear out your water pump by letting it run for the ~20min it would take to drain a FW tank?

Or do you mean to flush the lines a little, then drain the tank with the manual gravity drain?  (outside spigot that spills outside the RV on the ground)
I usually use city water hooks-ups to flush the water lines. Partially fill the fresh water tank and drain once or twice. I usually partially fill the hot water tank and drain before refilling.


But when you flush your fresh water tank w/ bleach water, you only fill it partially?  Maybe I've been going overkill...
Hi Ho:  It really doesn't matter too much how much water in the fresh tank.  Just adjust the amount of chlorox accordingly.  The reason for partial fill is so the solution can slosh around when driving.  It gets mixed up that way.  It just takes a couple of minutes more to drain the excess if the tank is full (or nearly full), but that's also not a big deal.
Some RV's have drain valves on the tanks so you can just open them to drain the tanks.  Refill, run water thru lines and drain again.  You then don't  have run the pump as long.
When you are flushing or sanitizing be sure that you flush/sanitize with the Bypass for the Water Heater both in Bypass (winterizing) and Normal position.  You would be surprised how long that little bit of Antifreeze left in the bypass tube will affect the taste of your water especially if it is parked more than used.
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