Draining an RV Water System

When you return from a trip and you’re not going to use the RV for a while you need to drain the entire water system to prevent it from getting stale and musty. You can start by draining the water heater. If the water heater has an electric mode make sure it is in the “off’” position before you drain the water heater tank. It’s a good idea to turn the breaker for the water heater off, so the switch doesn’t accidentally get turned on with no water in the tank. Go to the outside compartment where the water heater is located. The drain plug, or petcock is normally located in the bottom left hand corner. Remove the plug and open the pressure relief valve on top of the water heater to assist in draining. (See Caution below)


If you have a Suburban water heater you will need to remove the anode rod with a 1 -1/16 inch socket to drain the tank. The anode rod is designed to help prevent corrosion and protect the tanks steel lining. Corrosive elements in the water will attack the rod rather than the tank. Inspect the anode rod every time you remove it to drain the tank, and replace it when 3/4 of the rod is consumed. Atwood water tanks do not require an anode rod and use a nylon drain plug because the tank is made of aluminum.

Caution: Never drain the water heater when it is hot and/or under pressure. Turn off any water going to the RV, to include the water pump, and open a hot and cold faucet to relieve water pressure. Allow sufficient time for the water in the tank to cool before draining. Draining a tank that is hot and/or under pressure can result in serious injury.

Next you need to locate the low point water line drains. It may take a while to find them. There will be one for the hot and one for the cold water lines. This is the lowest point in the water system. Open these and let the water drain out. Now locate the drain for the fresh water holding tank and drain all of the water from it.

At this point you can turn the water pump on for a moment to force any remaining water out. Do not let the pump continue to run once the water stops draining. Close all the drains. Do not make the mistake of thinking this is how you winterize the RV water system. If you do, it can be a very costly mistake next spring. All we have accomplished so far was to evacuate the majority of water from the system. If by accident you forget to drain the water system and you get that notorious stale odor all is not lost. You just need to sanitize the water system.

Start by draining all of the old water out, and then close all of the drains. Take a quarter cup of house hold bleach for every fifteen gallons of water that your fresh water tank holds. Mix the bleach, with water, into a one-gallon container and pour it into the fresh water holding tank. Fill the fresh water tank completely full of water. Turn the water pump on, open all of the hot and cold faucets and run the water until you smell the bleach at each faucet. Close the faucets and let it sit for about twelve hours. Drain the entire system and re-fill the fresh water tank with potable water. Open all of the faucets and run the water until you no longer smell any bleach. It may be necessary to repeat this process again to eliminate all signs of bleach from the water system.

Once this is done it is safe to use your water system. It’s also a good idea to use a water filter at campgrounds and to keep bottled water on hand for drinking.

Happy RV Learning,

Mark Polk
RV Education 101
RV Online Training