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Frigid Temperatures can be an issue for RVs, especially the water system. Water expands when it freezes so if there is any water in the components of the water system it may cause damage as this expansion occurs. It is wise to prepare these parts of the RV when storing the RV in a location where freezing temperatures may occur.

Rinse and Drain the Holding Tanks

  • Add water to both the sewage (black) tank and the wasterwater (gray) tank filling them both to about 1/3 full of water.
  • Completely drain the sewage and wastewater tanks in the appropriate disposal site. As usual it is good to drain the sewage tank first followed by the wastewater tank. This helps to rinse the solids from the dump outlet and hose.
  • Close the dump valves to keep the stems of the valves from rusting and replace the outlet cap to keep unwanted critters from entering through the tank outlets.
  • Add either 1/2 - 1 gallon of non-toxic antifreeze or windsheild wiper fluid to the sewage and wastewater tanks to help prevent freezing of any residual water that might remain in the these tanks. Windsheild wiper fluid can be used in these tanks because it functions as an antifreeze does not damage any of the components and is less expensive than the non-toxic antifreeze that should be used in the fresh water part of the system.

Drain the Fresh Water Side of the System

  • Level the coach so that water does not pool in the fresh water tank or other locations in the fresh water system.
  • If a purifier system is installed in the system remove the filters and follow the water purifier manufacturers instructions for winterizing these components.
  • Open all the drain valves. These can be found in various locations. Check the RV manufacturers owners manual for the location of the various drain valves. There may be drain valves for the fresh water holding tank and low point drain valves for the piping system.
  • Turn on the water pump and leave it on until all the faucets and fixtures are fully drained.
  • Open all the water valves - sink faucets, shower valves, shower head valve, exterior shower valve, toliet flush valve, and any other fresh water valves that might be located in the RV. Once the water stops flowing from all of these locations then turn off the water pump.
  • Drain the water heater tank. This is done by removing a drain plug that is usually located at the bottom or base of the tank. This will require a large socket and ratchet to remove. Open the pressure/temperature release valve which is a fitting usually located near the top of the water heater. There is often a small lever on this fitting that can be lifted or pulled. This will allow the tank to drain by providing atmoshpheric pressure relief, which allows the water to flow. Air-lock or a pressure build up may occur and not allow the water to easily flow, if there is not a way for the air pressure inside the tank to equalize with the air pressure outside the tank.

At this point, there are two methods to prepare the pipes for frigid temperatures.

Air Pressure Blow Out Method

  • Purchase a blow-out plug (also called a water purge adapter) from an RV store and connect it to the city water connection. The blow-out plug has a garden hose connection on one side and an air pressure connection on the other side. Some blow out plugs or fittings include a ball valve. The helps to keep from bursts of air pressure from initially surging through the system.
  • Allow the air to flow through the system for about 5 minutes to help remove more of the water from faucets and drains. After about 5 minutes, close the faucets one at a time until all fixtures are in the off position.
  • Operate the toilet flush valve until any remaining water is removed from the toilet.
  • Turn off the air pressure and disconnect the blow-out valve.
  • Return the cap to the city water connection to keep critters or dirt from entering the fresh water system.
  • Reopen the faucets and other internal fresh water valves to allow for any remaining water to expand.
  • Reinstall water heater drain and close the pressure/temperature relief valve.
  • If an ice maker is installed, open the valve and drain the icemaker supply tube. Also drain the hot and cold water lines of a clothes washing machine, if one is installed in the RV.
  • Pour about a cup or two of non-toxic RV antifreeze into the kitchen sink, bathroom sink, and shower drains. This will help prevent any tank odors from entering the living area.

RV Non-toxic Antifreeze Method

This method pumps RV non-toxic antifreeze into the plumping lines and fixtures. For this method to be effective there are a few items that are needed.

  • A hand pump kit to pump the RV non-toxic antifreeze into the system.
  • A water heater bypass kit will need to be installed, which is a set of valves and bypass tubing which are installed to the inlet and outlet pipes of the water heater to separate the water heater from the rest of the plumbing. If this is not used then the entire water heater tank would have to be filled with RV non-toxic antifreeze, which is cost prohibative and unnecessary.
  • RV non-toxic antifreeze. The amount depends on the RV but often 3 gallons of premixed RV non-toxic antifreeze will suffice. Concentrated RV non-toxic antifreeze may also be purchased, which will require mixing with water for the proper concentration. Directions on the bottle should be followed to acheive the correct concentration.


  1. Engage the water heater bypass valves to separate or close off the inlet and outlet piping to the water heater tank. This allows the non-toxic antifreeze to bypass the water heater tank.
  2. Connect the hand pump outlet hose to the city water connection. Insert the pump inlet hose into the container of RV non-toxic antifreeze.
  3. As the RV non-toxic antifreeze is pumped into the RV fresh water system one by one open the various faucets until about a cup of antifreeze flows through the fixture. Then close the valve on the fixture and move to the next fixture. Do this until all the water lines to each fixtures/appliances have been filled with RV non-toxic antifreeze.( Start with the fixture that has the highest elevation: kitchen sink, bathroom sink, shower, shower head, exterior shower, toilet, washing machine hot/cold valves, ice maker, etc.)
  4. Pour about a cup or two of non-toxic RV antifreeze into the kitchen sink, bathroom sink, and shower drains. This will help prevent any tank odors from entering the living area.