There are different ways to winterize an RV, some of which may require less anti freeze then the four gallons I generally use, but FWIW here’s my method which I have used for well over thirty years. First of all, I highly recommend a water heater by pass plumbing job which isn’t that hard or expensive to install. If you don’t have one, when you try to run AFZ throughout the hot water piping none flows (only water) UNTIL the 6/10 gallon water heater tank has completely filled with AFZ. That’s such a waste of time and expense if you have to fill 6 gallons of AFZ into the water heater tank before it can flow out the tank and into the hot water lines. NOTE there are methods to use a pressure air line adapter to blow water out the lines, but that can end up with water still in a low point in the system, still use it if you like, it’s your RV.


1)      I first drain the fresh water holding tanks. Most have a drain valve somewhere under the RV that’s plumbed to one bottom corner of the fresh water holding tank. I find which corner that is then drive/tow the RV somewhere in the drive or yard or hill ect. so that corner of the tank is at the lowest point so almost all the water gets drained.

2)      Of course, I also open the hot water heater drain valve/cock and an inside hot water faucet (for air bleed) to drain the hot water heater completely. Once that’s done I close the drain valve and set the water heater by pass ON  so no more fresh water enters the tank, but its instead diverted to what’s normally the hot line output (such is the function of the hot water by pass system).

3)      After the fresh water holding tank is empty, I determine which other corner of the tank bottom has the line that leads to the water pump supply/input and I drive/tow the RV so that corner is now at the lowest point.

4)      I add approximately 3 gallons of AFZ to the gravity filler opening on the fresh tank top, turn on the water pump, and go to each and every faucet (hot and cold) and open them just long enough that the red AFZ flows out. At first it’s clear water that flows, but as its purged and the pump starts to supply AFZ, it will turn red. The AFZ will also flow down into the sink and lavatory drain traps which prevents them from freezing.

5)      Similar to the above, the toilet water system needs to have AFZ all throughout it, so I let it flush/run until the red AFZ appears and a bit is left in the bowl.

6)      Once ALL faucets run red with AFZ I use the final 4th gallon to add just a bit to each sink or lavatory drain and toilet to insure the traps are protected, then I add the rest again to the fresh water holding tank top gravity filler. Then I turn the hot water tank by pass OFF so water flows into the tank like normal, turn the pump on and turn on a hot water faucet which forces the remaining AFZ into the bottom of the hot water heater.

7)      I then turn the water pump off and open every faucet and put the RV to bed for the winter

8)      Finally if you want to use less AFZ then I use above, there are kits sold which you stick a hose down into the RV AFZ bottle and attach the output direct to the water pump input so it flows direct from the AFZ bottle instead of via the fresh water holding tank as I use. The expensive RV’s can have such built in. I believe other kits allow you to reverse pump AFZ into the faucet outlets but that just not my thing.


            I also air the tires to their max load at X PSI pressure,,,,,,,,,,avoid the tires being

           left on mother earth, cover tires to reduce UV damage,  either take the battery

            to a  safe  heated space or connect it to a battery maintainer,,,,,,,,,,,,,if a

           motorhome I add a good quantity of gas Stabilizer such as Sta Bil, ,,,,,change the

           oil and service filters etc. In addition at least once a month it should be started

           and driven if possible and pump the brakes and start the Generator if so equipped

          and let it run at least 30 minutes preferably with a load such as the AC fan running.



  John T in Indiana  Dry Camping Special


  2001 Chevy Four Winds 29 ft Class C

  454 Vortec with 4L80E Overdrive Tranny

  110 Gallons Fresh Water Storage, 80 Gallons gray storage

  460 Amp Hrs (4 Golf Cart) House Battery Energy Storage

  Xantrex Truecharge2 Smart Three State House battery Charger

  200 Watts of Rooftop Solar Panels and Charge Controller

  Onan 4 KW Genset

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Comment by Jim-N-Bear on November 11, 2013 at 10:23am

Thank for the info I have not had to winterize a RV since I owned a Mobile Travler in the mid to late 80's

my wife and i now own a 1976 Traveco L'Spirit and need to get it done. I printed the info And will use it

Thanks again


Comment by John "T" Nordhoff on October 13, 2013 at 9:22am

Thanks Henry, and to add to that Murphys Law dictates that if a water line does freeze and burst, it happens in the most hidden hardest to get at location in an RV like deep under a floor or inside a wall grrrrrrrrrrrr. My method takes a bit more AFZ but by golly if you get red out ALL the faucets and into the toilet bowl and you fill the drain traps with red AFZ and of course, the pumps is full of AFZ itself, you're gonna be safe......... That method whereby you use the water pump itself to pump AFZ out of a bottle saves AFZ but I like the AFZ also being in the fresh holding tank bottoms and a bit in bottom of water heater even if it costs a few more bucks.


 John T in Indiana (currently hold up in Austin texas)

Comment by henry thomason on October 13, 2013 at 9:15am

Great job I've seen in 43 years of Rving in fact..

For those who just drain or blow air through their water system..most RV commodes flush/fill valves always have water left in them that will not drain out without removing the commode and turning it up side down..

As john suggest be very sure the AF runs very very red through the commode valve. My wife and I learned this the expensive way back in 1972.



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