How to Winterize your Travel Trailer, Rv,
5th trailers, motorhomes, class c, rvs 5th wheel &
Toy hauler.

There are two generally accepted methods of winterizing an RV’s fresh water system.

  1.  (Wet) Method Uses RV approved, nontoxic, potable, anti-freeze in the system. You can put antifreeze into the fresh water tank or you can purchase a winterization kit that attaches to the water pump.  The winterization kit is the method of choice as you do not get the antifreeze task in your drinking water.

This method also reduces the amount of antifreeze used thus reducing your cost.

1.  (Dry) Method Uses compressed air to blow out any remaining water in the system after draining the system of all water. This method requires an air compressor and appropriate adapters.

We’ll cover the procedures for both methods in turn.

Many late-model RVs include a by-pass valve kit that allows the plumbing system to by pass the hot water heater, reducing the amount of anti-freeze that will be needed. 

 Without a by-pass kit installed, an additional 6 – 10 gallons of anti-freeze will be required.

Turn the 2 valves on the intake and out lines to the off position; open the valve
that runs between the lines.

Rv water bypass valve on hot water tank

Rv water bypass valve on hot water tank

If your RV doesn’t have one we recommend you install a bypass valve. The by-pass kits are available at most RV service centers for a reasonable price and can be installed easily before winterization.

RV Winterizing with Compressed Air

If using the compressed air method, a special adapter should be purchased to allow compressed air to be delivered through the city water fill. These adapters are available at most RV supply stores.

Rv anit-freeze for travel trailers

Rv anit-freeze for travel trailers

  1. Purchase 2-3 gallons of RV non-toxic anti-freeze.
  2. Drain the fresh water tank and empty the waste water holding tanks
  3. Turn water heater by-pass valve to by-pass position. (The by pass valve is located between the water heater incoming & out going water lines.
    The rear of the water heater is usually accessible behind a cabinet door but you may have to remove an access panel depending upon the design of your RV.
  4. Drain water heater (remove drain plug from on the outside of the water heater.)
  5. If installed, remove water filter from assembly and discard.
    Install diverter if included.
  6. Open all faucets, including shower head sprayer, toilet flushing device and any other water lines that are closed.  Do not forget the outside shower.
  7. Open the two low point drains under the trailer.
  8. Turn on the water pump for 30 seconds to clear out any water in the lines.
  9. Connect an air hose with an adapter to the city water fill connection.

10.  Set the pressure no greater than 30 pounds and blow out the water lines until no water can be seen coming out of the fixtures and lines.

11.  Pour RV anti-freeze into drains, p-traps, toilet, and tanks.

Winterizing Your RV Plumbing System with RV Anti-Freeze


  1. Purchase 4 -6 gallons of RV approved, non-toxic, anti-freeze.
  2. Drain all tanks, fresh water and sewage tanks
  3. Turn water heater by-pass valve to by-pass position. (The by pass valve is located near the water heater incoming lines – an access panel may have to be removed depending upon the model.)
  4. Drain water heater.  (remove drain plug from on the outside of the water heater.)
  5. If installed, remove water filter from assembly and discard. Install diverter if included.
  6. Pour an amount of RV non-toxic anti-freeze into the fresh water tank to fill the tank above minimum water pump operating level. (Use of a long funnel may be helpful) Add more, if necessary, during procedure.)
  7. The most common way is to purchase a siphon hose kit and attach it to the water pump then insert the hose into the anti-freeze jug, turn on the water pump and fill all the lines.  This way you do not get the anti-freeze in you water tank.
  8. Turn on pump switch and open the cold water side of all faucet fixtures. Leave open until the anti-freeze comes out (generally, pink in color). Repeat for hot water side.
  9. Repeat this procedure on the outside shower.

10.  Open the 2 low point drains under the trailer, allow the antifreeze to come through the lines.

11.  Turn off the water pump, then de-pressurize the system, open a cold water tap.  On the outside of your unit is the city water connection, remove the screen and press on the small valve inside until antifreeze comes out.  Make sure the valve returns to the original position after relieving the pressure

12.  Flush toilet until anti-freeze begins to flow into the bowl and then pour one gallon of anti-freeze down the toilet to winterize the black tank.

13.  Pour anti-freeze down each shower/tub, lavatory sink, and kitchen sink to fill p-traps.

14.  To winterize gray tank(s) pour one gallon down each related sink drain.

For units with ice makers and water filters:

  • Drain and remove water filter, make sure to turn off bypass
    valve if your unit has one.
  • Units with ice makers and water in the fridge:
  • Turn off the water supply, there should be a valve in the
    back of the fridge or under the sink.
  • On the back of the fridge remove both links from the
    check valve.  Lightly blow through the line going to
    the freezer compartment to remove all the water from
    this line.
  • Run anti-freeze through the bottom line.

De-Winterization / Removal of Anti-freeze

If purchasing a recreational vehicle which is winterized with RV anti-freeze, or you had you existing RV winterized before winter storage, the plumbing system must be flushed and sanitized prior to use. Do Not Attempt to turn on water heater if system is winterized.

Perform the following prior to attempting to operate the water heater or use the plumbing system.

  1. Drain all holding tanks, fresh water and sewage*
  2. Attach garden hose to fresh water fill and fill tank.
  3. Turn on pump switch and open cold water side of all faucet/ shower fixtures. Leave open until water runs clear. Repeat for hot water side.
  4. Flush toilet until clear water runs into bowl.
  5. Dump tanks again.
  6. Sanitize water system. (See page 6-3 )
  7. If a water filter is installed, drain lines, remove filter assembly, clean and reinstall with new filter.
  8. When ready to use the water heater, turn by-pass valve to open position to allow water to enter and fill the hot water heater tank.

These are proceedures do not guartantee that your unit is winterized
properly.  To make sure book your Rv into your dealership for
if you wish to have it winterized professionally.
Rvworldnews takes no responsiblility for the information shared
on this site.  It is for informational purposes only.

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Ken Hatton

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