Plumbing Winterizaton: Compressed Air Method

If you choose to winterize the plumbing system yourself, you will need a few tools and supplies and approximately 2 hours of free time.

There are two methods used to winterize an RV: compressed air or RV antifreeze. The compressed air method uses an air compressor to blow the water out of the plumbing system.


  • adaptor for connecting the air compressor to your water lines
  • 1 - 2 gallons of RV non-toxic antifreeze. DO NOT USE Automotive Anti-Freeze. Automotive anti-freeze is poisonous and not for use in potable water systems.


  1. If your RV is equipped with a black tank flush, use the adaptor and compressed air to blow out any water that is in the system. Be sure not to exceed 30 PSI air pressure.
  2. Remove the low-point drain caps for the water lines and open all the faucets and outside shower if equipped to allow the lines to drain.
  3. Open the drain valve for the fresh water tank and allow it to drain completely.
  4. Verify the water heater is turned off on both gas and electric.
  5. Remove the water heater drain plug and open the pressure relief valve to let air in the tank and allow it to drain. (If your unit is equipped with a tankless water heater, please refer to operator’s manual for the winterization procedure.)
  6. If you have a water filter, remove and discard the water filter cartridge. Drain the water from the base and reinstall. If equipped use the bypass tube for cartridge filters.
  7. Empty the waste water holding tanks at an approved waste water dump station.
  8. Turn the water heater bypass valves to the bypass position. The bypass valves are located on the water lines entering the back of the water heater. Depending on the model of RV you own, you may have to remove an access panel to reach the bypass valves.
    The easiest way to locate the by-pass valves is to locate the water heater on the outside of the RV. The by-pass valves will be located on the back side of the water heater on the inside of the unit or in the basement storage compartment.
  9. If your RV has a residential refrigerator the ice maker water line should not be winterized with antifreeze. Simply drain the line along with the rest of the water lines, but do not add antifreeze.
  10. After the water has drained from the fresh water tank, turn the water pump on for about 30 seconds to clear out any water in the suction line and pump.
  11. Using the adaptor, connect an air hose to the city water fill connection. Set the air pressure to no more than 30PSI and blow out the water lines until no water can be seen coming out of the fixtures and lines.
  12. Hold open the toilet valve until the water is cleared from the toilet supply line.
  13. Open the diverter valve on the shower faucets to clear the shower hose and head.
  14. Don’t forget the outside shower or kitchen if equipped.

If equipped with a washer hookup follow these steps:

  1. If there is a washer hooked up, turn the washing machine on to the fill cycle using a warm water setting to open both the hot and cold valves.
  2. Allow air to blow through until no more water comes through.
  3. If there is no washer hooked up, open the hot and cold valves allowing the water to clear the lines.

Pour about one quart of RV anti-freeze into each drain, p-trap, and toilet. Leave a little antifreeze in the toilet to maintain the air seal. Don’t forget the washer drain if equipped.

Once the water is removed from the water lines, water heater and fresh water tank it’s a good idea to reinstall the drain caps and plugs and close the valves to keep critters out of the fresh water system.