One of the most vulnerable parts of RV's is the plumbing system. If the plumbing lines freeze, then it could cause detrimental damage to the entire plumbing system creating a very expensive repair and in turn possibly take away from the finances and enjoyment of RV Camping.
There are many different approaches to winterizing your RV plumbing system, but ultimately the objective of each method is to clear the pipes of any kind of water or moisture. Each RV is different in its construction and build and you should consult your owners manual or RV dealer to discuss which method will work best for you if you are unsure.
The most common method of RV winterization is the RV antifreeze method. The first step in this method is to clear out all of the existing water (fresh/black/grey) with an air pump. The air pump can be connected using an adapter and an air compressor or the hand pump. Turn on the air to no more than 30 PSI of air pressure and make sure that all of the black water is pushed out of the system until you don't see it coming out anymore.
After you have drained the black water from the tank, you should now start emptying the fresh water. First drain the water from the low point drain, then open all of the faucets, showers (inside and out), and other water outlets to empty out any potential water storage. After that, drain the fresh water tank and make sure to turn off the water heater (both gas and electric). From the outside of the RV, the hot water heater cap needs to be removed and the pressure relief valve should be set to release any pressure. Once the fresh water lines and hot water heater has been drained, the bypass needs to be switched on from your hot water heater (the bypass will vary depending on the kind of RV that you have).
After the water is released from all of the lines (gray/black/fresh), a bypass hose needs to be installed on the suction side of the water pump. This suction hose will run directly into a container of RV antifreeze and pump it throughout your water system. It is VERY important that you use approved RV antifreeze because it is non-toxic, automotive antifreeze is very hazardous and should not be used in your RV waterlines.
After the bypass hose is installed, the low point drain plugs need to be tightened again and the faucets and water outlets need to be closed. Next you must turn on the water pump to circulate the antifreeze through your waterlines. Turn on the cold side of your faucets until antifreeze comes out of the water outlet followed by the hot side on all of your water outlets. For the toilet, flush it until you see antifreeze come out of it and allow one quart to go into the bottom to winterize the black tank as well as leaving some in the toilet to seal air pockets from getting in.
If your RV has a washer in it, then you need to set to fill cycle using cold water setting till anti freeze comes out of it. If your washer is removed then follow the same procedure as the other water outlets and run the cold water until anti freeze comes out followed by the hot side.
Upon finishing all of your water outlets, pour a quart of antifreeze into each of the sinks and water drainages to run through the lines and close all of the open exterior water drainages to avoid getting dirt, or bugs and animals in them.
Along with winterizing the plumbing system of your RV, its very important to keep your RV clean. Make sure that all substances are sweeped and wiped down from all food and substance exposure. Animals can easily make a winter home in your RV and possibly damage things like the interior or wiring.
If at any point you feel uncomfortable with winterizing your own RV, make sure to call your local RV dealer or pick up tips from online RV forums and tutorials. With so many different RV's and maintenance options on them, it can easily be confused and possibly done incorrectly. Winterizing your RV is a simple task that is extremely important to maintain the quality of your RV.
Make sure to winterize your RV correctly to be able to head out on RV camping trips ever summer!