The fresh water system of your RV consists of many components starting with the fresh water tank and going all the way through to appliances such as on-demand water heaters, ice makers, and even the black tank flush valve. Getting all the water out of the pipes and components with either RV antifreeze or compressed air is crucial to reducing expensive repairs due to freezing conditions. There are several hidden areas that you will want to know about when winterizing your rig to keep your pipes from freezing over.
Your Fresh Water Tank
Almost every RV has a freshwater tank that can be filled to supply pressurized water by the onboard water pump. This is filled by a hose being fed into the gravity feed on the rig’s side. Typically a hose is connected to a pressurized outside source such as a campground faucet but can also be filled using a portable container in the case of boondocking. This picture shows the gravity feed at the top just above the city’s water fill.
Whether you choose to use RV antifreeze or compressed air, the first step is to drain the fresh water tank by using the drain valve located close to the tank itself. Some models have a large 1.5” drain valve attached directly to the tank. This photo shows the drain valve connected to a ½” plastic pipe coming off the tank which will take much longer to drain. Also, notice that there will still be an inch or more water standing at the bottom as the drain port on the tank is not at the very bottom which is typical and even though is water will freeze in the tank, it will not cause any damage as there is room for it to expand.
The Low Point Drain Valves
Next, locate the drain valves placed in the water lines that are at the lowest point in your rig called low point drain valves. These can be handle valves that have a ball inside with a hole like the above photo you turn the handle and it opens the line to drain. Other types have a pull-up and push-down valve with a ring at the top, and price leader units just have a hose coming out the bottom with a plug.
Keep in mind, that just opening the low-point drain valves will not get all the water out of your rig. There is still water in some of the lines that loop in and around lower cabinets, going to the ice maker, and the black tank flush valve.
The Water Heater
You will want to drain the water heater by removing the drain plug and turning the bypass valve if your rig has one. Suburban water heaters have an anode rod that should be inspected and replaced if the metal is over 50% deteriorated. This is also a good time to flush out the bottom of the water heater as there will be about 1.5” or more of standing water. The drain plug is not at the very bottom so the hard water full of calcium, rust, and lime typically sits in the bottom for several seasons if not flushed. Just replace the drain plug and let it sit.
If you have an on-demand system, check your owner’s manual for recommended procedures. The Girard system by Lippert states that even using compressed air will not remove all the water in the boiler and tubes and it is recommended to flush it with RV antifreeze. The Truma Combi claims you can drain all the water out of the system and do not require RV antifreeze. And Aqua Hot also recommends draining and then flushing with RV antifreeze.
Using Compressed Air
This is my method of choice for winterizing the water system as it is easy with the correct adapter and the unit isn’t filled with the “pink stuff”. I made an adapter that allows me to connect to the city water fill valve with a ¾” air plug that I purchased from my local home improvement store.
Connect an air compressor hose and dial the compressor down to 40 psi so you don’t blow out the fittings, then open the farthest faucet and let it run until air comes out. Do this to all the faucets, shower heads, and toilets. Don’t forget the toilet flush wand, the ice maker if your refrigerator has one, and the black tank flush valve. Most of these have a remote connecting valve in the service compartment and a hose running to the actual valve on the tank. This hose can be 6’ long and will be filled with water and freezing temperatures will create a mess that is hard to get to. Keep in mind the hose going to the onboard water pump, the pump and screen itself, and the outgoing line will also have water so you will need to turn that on to drain that water as well. Then it is a good idea to dump a cup of RV antifreeze in each sink as the “P” traps will have water in them as well. If you have an icemaker, it is best to remove the filter under the sink first, shut off the valve, and then cycle the icemaker several times to get all the water out.
Using RV Antifreeze
If you have a winterizing kit or valve, adding RV antifreeze is easy and relatively mess-free. This valve is typically located in the service compartment with a hose attached. Turning the valve to winterizing reroutes the draw from the onboard water pump from the fresh water tank to the hose which can be inserted into a gallon jug of RV antifreeze. It will take more than one gallon so I typically dump 4-5 gallons in a bucket to draw from rather than inserting the hose into 4-5 jugs and risk getting air. With everything drained as covered earlier and the water heater in the bypass mode, start the pump and open the farthest faucet until you see the pink stuff. Do this to all faucets, shower heads, toilets, sprayers, and outside showers. If you have an icemaker, it is best to remove the filter under the sink first, shut off the valve, and then cycle the icemaker several times to get all the water out rather than add RV antifreeze.
If you don’t have a winterizing valve, you will need to fill the fresh water tank with enough RV antifreeze to be drawn by the water pump and this can be a little more work cleaning it out in the spring. Don’t forget the black tank flush valve during this procedure as well.
Another option if you don’t have the valve is to use a small portable pump such as a fountain pump or small sump pump and make an adapter that comes off the pump hose with a ¾” city water fill adapter. Place the pump in a 5-gallon bucket with RV antifreeze and flush the system. This is also a good adapter to have for the black tank flush valve as it can not be supplied with pressure from the city water fill or the onboard pump so you will need to connect directly to that valve with either air or RV antifreeze. This photo shows the valve on the left next to the water filter.
Properly winterizing your RV’s fresh water system is crucial to prevent costly repairs in freezing conditions. By following these steps, your freshwater pipes will remain protected during the cold months, ready for the next season’s adventures. Stay warm and keep your RV safe!
About the author: Dave Solberg: Managing Editor, RV Repair Club
For the last 25 years, Dave has conducted RV maintenance and safety seminars, developed dealer and owner training programs, written RV safety and handyman articles authored an RV handbook reference guide, and logged over 100,000 miles on the road in an RV.
RV Repair Club is your go-to online resource for enthusiasts who want quality RV maintenance, repair and upgrade information – a community where passionate RVers can come together to gather knowledge and share their experiences.
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