How To Winterize Your RV

The steps listed below will familiarize you with the process of winterizing your RV, either by blowing out all the water lines with compressed air, or by replacing the water in the lines with non-toxic antifreeze. Choose the process that works best for you. For both versions, you’ll need to drain your system first.

Draining the system

Step 1: Drain the freshwater tank

1. To find the drain, first locate the freshwater fill.
2. The freshwater tank (or) potable water tank will be inside the trailer at the point of fill.

Some RVs have subfloor water tanks, but they will always be located by the water fill location.

• If your tank is inside your RV the drain may be:
  At the base of the tank
• On the tank itself
• At the end of a short plumbing line
• On the outside of the RV below the water fill
• Under the RV on a stanchion coming down through the floor.

Note: If your tank drains slowly, you may wish to look for water line drain outs and speed up the process by opening the drains and turning on your water pump. Most pumps can move approximately three (3) gallons per minute, so you can drain a 40-gallon tank in about 13 minutes!

If the water tank is in an insulated subfloor, the drain will usually be located on the bottom of the tank under the RV. Also, some tank drains are routed out through the main frame of the RV and are hidden behind the wheels.

Step 2: Drain the Water Heater

1. Turn off the 110-volt element in your water heater. To do this, switch both the wall switch AND the switch located the water heater to the “off” position. ( Note: If you have a 1994 or newer unit, the “on-off” switch may be on the outside of the water heater, tucked under the control valve.)
2. Locate the drain plug, usually on the bottom of the tank inside the water heater access door, and on the outside of the RV.
3. Using your ½ in. ratchet drive, remove the drain plug. The drain plug will be either plastic or metal. Be sure to use the correct socket size on the drain plug because some drain plugs are very tight. If your unit has a drain cock instead of a plug, it will look like an automobile radiator drain. Turn the drain CLOCKWISE to open. Next, pull the “pop-off” valve to the straight-out position. The “pop-off” valve is the brass valve at the top of the outside face of the water heater. This will relieve the vacuum in the water heater tank and allow it to drain.

Step 3: Drain your plumbing system

1. Locate your low point drains, if your RV is so equipped, and open them. To find your low point drains, follow your plumbing lines through your RV. The drains will have pull-up “T” valves if they are inside the RV. Some RVs have low point drains outside, under the unit. These outside drains will be either two 90-degree valves, or two lines with caps or plugs.
2. Next, open all sink and shower faucets in the RV. This will allow most of the water in the system to drain. After all lines have finished draining, turn on the water pump and run it for five minutes. This will clear out the freshwater tank-to-pump pickup line.
3. Now you are ready to drain the screen housing, if your vehicle is equipped with one. Check to see if your water pump has a water pump filter screen mounted on the intake side of the pump. If it does, simply turn the screen housing counterclockwise to open.
4. After all water is removed, re-assemble the pump screen housing. If your unit has a water filter, a winterize plug was provided at the time of purchase. Remove the filter and install the plug.

Winterization with Air Supply

Supply List – What you will need:

• A compressor capable of maintaining 100 PSI maximum output
• City water inlet hose thread to air hose quick connector adapter
• ½ in. drive ratchet with long extension and sockets
• One gallon of non-toxic antifreeze
• Shop towel or rags to wipe up splattered water
• Channel Lock Pliers

Step 4: Blow out your water system

1. Connect your compressor to the city water inlet with the air-to-water hose adapter. Go through your RV and close all faucets and drains, leaving only the kitchen “cold” side open. Tip: Hang a damp wash rag or shop towel over the faucet to reduce water splattering.
2. When all water is blown out of that line, open the “hot” side of the kitchen faucet.
3. Then, with both “hot” and “cold” faucets open, close the “cold” side of that faucet.
4. Repeat this procedure for the bathroom sink, the shower, the toilet valve, and the outside shower if your unit is so equipped. Always leave at least one faucet open, so as not to build up excessive pressure in the water system. On units with single-mixer faucets, you can simply switch from “cold” to “hot” and no other faucet has to be open during that process.
5. Toilet Valve: To aid in holding the toilet valve open, simply open the flush valve and insert a short piece of 2” x 2” wood directly into the flush opening. Let the valve close on the 2” x 2”, and this will keep the water flush valve in the open position.
6. Finally, remove the water heater drain plug and blow out any water that may have collected in the bottom of the water heater. Also, re-open the low point drains and make sure no water remains down in the stanchions, aka – the main drain lines, or main pipes that run through the floor and are responsible for all drainage. Replace the water heater and drain line caps or plugs. All drain plugs should now be tightly in place.

Step 6: Prevent your drain traps from freezing

1. To keep the sink drain traps from freezing, pour three cups of non-toxic RV antifreeze down each drain.
2. Be sure to complete this process for all three drains – the kitchen and bathroom sink, and the shower drain.

Step 7: Drain the holding tanks on your RV

Now that you’ve drained all water out of your freshwater tank, now you need to drain the black and gray holding tanks at an RV dump station. The Pro RV Repair Prineville location includes a dumping station, open 24-7, and is $5 per visit. Our Bend and Vancouver facilities do not have dumping stations.

Winterization with Antifreeze

Supply List – What you will need:

• Two gallons of non-toxic RV antifreeze
• Paper towels or shop rags to wipe up small spills
• A water heater by-pass kit, on the water heater water inlet line
• A 5’ length of ½ in. tasteless water hose

Step 4:

1. Disconnect the freshwater inlet hose from the water pump. This is the supply line from the freshwater tank.
2. Connect the 5’ length of water hose to the pump where you just removed the water tank inlet line.
3. Secure the 5’ hose with the same clamp that was used on the original hose. Place the other end of the hose in one of the two gallons of antifreeze.

Step 5: Switch the water heater by-pass valve to the “by-pass” position. If you neglect this step, you will fill up your water heater with antifreeze, adding six to ten more gallons of antifreeze to your shopping list.

Step 6: Turn on your water pump. Open each faucet in the RV and let the water run until it turns the pink color of the antifreeze. When you have finished this, re-connect the water hose to its original position and switch off the water heater bypass valve.

Step 7: Prevent your drain traps from freezing

1. To keep the sink drain traps from freezing, pour three cups of non-toxic RV antifreeze down each drain.
2. Be sure to complete this process for all three drains – the kitchen and bathroom sink, and the shower drain.

Step 8: Drain the holding tanks on your RV

Now that you’ve drained all water out of your freshwater tank, now you need to drain the black and gray holding tanks at an RV dump station. The Pro RV Repair Prineville location includes a dumping station, open 24-7, and is $5 per visit. Our Bend and Vancouver facilities do not have dumping stations.

To de-winterize your RV

Simply fill your water tank and run the water pump until water has recirculated throughout the entire water system.

Don’t forget to scroll up to see the full process. 

Disclaimer: This document has been written and designed by Pro RV Repair Prineville, Oregon. These processes were written by Loren Cassidy. We don’t mind if you share it with a family, friend or neighbor, but it cannot be used for other commercial purposes without the prior authorization and consent of Pro RV Prineville.