Winterizing Your RV’s Water System

How to safely prepare your RV for freezing temperatures

RV Winter Camping
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With summer’s end, it’s time for many RVers to put their RVs in winter storage. The main system you need to winterize is the water system. This becomes more important for storage in colder climates as freezing water can burst your pipes, break seals, and end up costing plenty to replace everything. Make sure to brush up on safety tips for storing RVs.

RV Winterizing Supplies

To prevent any residual water from freezing in your water lines, you’ll need the following supplies:

  • Two or three gallons of non-toxic antifreeze made just for RVs. You can buy this at any RV supply store. The amount will depend upon the size of your RV and the amount of plumbing you need to flush.
  • Holding tank cleaning solution and a cleaning wand for holding tanks OR Some laundry detergent and a bag of ice cubes
  • Lubricant (e.g., WD-40)
  • A water-heater bypass kit
  • Tubing for the water pump inlet
  • Tools for removing drain plugs
  • Your owner’s manual
  • A 30 to 50 psi air compressor
  • A blowout plug for the city water inlet

Read the manual carefully for all instructions and warnings about draining water lines, adding antifreeze, and other winterizing information. Different RVs might have different specific ways to do any of the required steps.

Be sure to drain all of your holding tanks and plumbing into a sewer system (as compared to your front lawn, or some open space in the desert.) Since the hot water tank will be clean water, just drain where it is safe. Don’t make mud under your RV. It’s slippery (and messy.)

How to Drain RV Water Lines

If you are going to blow the water out of your plumbing system, connect a blowout plug to the city water inlet, and then connect your air compressor. Blow air through the lines at as close to 30 psi as possible, opening one faucet or valve at a time until all have been cleared. Close the last valve and disconnect the compressor, and remove the blowout plug. This should remove water from water traps and low-level plumbing eliminating the possibility of freezing.

  • Remove the hot water tank drain plug
  • Drain the hot water tank
  • Replace the hot water plug

Alternatively, you can simply drain the tanks and plumbing, but this will leave water in water traps and low areas of plumbing.

  • Remove and bypass all inline water filters
  • Drain the fresh water holding tank
  • Drain the gray and black holding tanks
  • Flush the gray and black holding tanks

If you don’t live where temperatures drop below freezing, you won’t have to add the antifreeze to your system. But if there is any chance of freezing temperatures, any water that remains in your system can freeze, expand and damage your plumbing system.

Now, there are a few ways to clean out the black and gray tanks. One is using the wand and a cleaning solution designed for RV holding tanks, which involves manually scrubbing the inside of these tanks. The other is to pour a cup of laundry detergent into each tank then fill with about ten gallons of water. Dump the ice cubes into the toilet and flush into the black tank. Then drive about 20 miles, up and down hills and around curves, letting the ice cubes do the scrubbing for you.

  • Flush the black and gray tanks one last time.
  • Lubricate the valves with WD-40 or other lubricating oil
  • Make sure the hot water heater contents are not hot
  • Remove the hot water heater drain plug
  • Open the pressure relief valve
  • Open all faucets (hot and cold)
  • Open the toilet valve
  • Open the outside shower valves (if you have one)
  • Open and drain the hot and cold drain lines
  • Replace all the drain caps
  • Close all the faucets
  • Install the hot water heater bypass kit–this will save filling it with an unnecessary six to ten gallons of water
  • Using either a water pump converter kit or a piece of tubing attached to the inlet of the water pump, insert the other end of the tubing into a gallon of antifreeze.
  • Turn on the pump to start circulating the non-toxic antifreeze
  • Open the hot and cold water valves, starting with the one closest to the pump, and watch for antifreeze
  • Close each faucet as you go
  • Change bottles as they empty
  • Flush the toilet until you see antifreeze
  • Turn off the pump
  • Open a faucet to relieve the pressure
  • Check the outside water inlet connection: remove the filter screen and push and hold the valve open until you see antifreeze, then replace the filter
  • Now pour a cup of antifreeze down each drain, and a couple of cups into the toilet, flushing into the black tank
  • Close your faucets

It's also important to remember to turn the water heater off if it is electrically powered. And make sure to flush the RV water system when you are ready to go camping again.

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