Draining an RV Water System

March 5, 2008 by Mark Polk · 14 Comments  
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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.

 Low point water drains

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.

Fresh Water Drain

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 Camping

Mark Polk

RV Education 101

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14 Responses to “Draining an RV Water System”

  1. Mark on March 5th, 2008 4:57 am

    Great article Mark! Very easy to follow. As newbies, we appreciate all the how to information we can get. Will use this article upon our return to Canada in May. Many thanks!l

  2. Rick on March 14th, 2008 4:13 pm

    I am a newbie also, thanks for the information..

  3. Rickie on March 26th, 2008 9:56 pm

    Many Thanks! Mark you did fantastic job. Your article is very clear. I have one question. Last October we winterized our camper. Soon we will open our camper this Saturday. Do I need to do like you explain pour 1/4 cup of bleach in the fresh water holding tank? In matter of fact we never use water for drinking. We use it for shower or wash dishes.

  4. Mark Polk on March 27th, 2008 7:58 am

    Some people recommend sanitizing the water system on an annual basis and others say you only need to sanitize the water system when you notice an odor. I usually do it as part of the de-winterizing process just to be safe.

  5. Yakman on March 27th, 2008 3:04 pm

    What about a new RV. Do you need to sanitize the water system or does the dealer normally do it prior to delivery?

  6. Charles Jenkins on March 29th, 2008 2:23 pm

    Question about the hotwater tank operating when the outside temperature is below freezing but the inside temperature is keep at 70 F. The trailer is a 2007 Airstream 28 ft Safari. The water heater is located well exposed to the inside air just next to the kitchen sink. The operating manual states “The furnance on Safari models except for the 22 ft. and 23 ft. models is ducted to provide heat to tanks and plumbing to prevent freezing.”

    The statement in the manual and my observation of the water heater mounted exposed to the heated trailer air indicates, to me, that it is OK to use the hot water heater when the outside temperature is below freezing.

    The question comes up because a technician at the dealer where I purchased the Airstream and a technician from Airstream internet both told me to drain the hot water heater when the outside temperature is below freezing.

    I am new to this activity so I am cautious about going against technicians who are instructors. But this “does not compute”.

  7. Mark Polk on April 4th, 2008 6:16 am

    What the technicians were saying is not to allow water to stay in the water heater tank when you are not using the RV and temepratures are below freezing. The water can freeze and damage the tank.

    It’s okay to use the water heater in cold climates as long as you exercise caution to prevent it and other parts of the water system from freezing.

  8. Ray Wallace on April 10th, 2008 6:59 am

    I have a 2007 Coachmen Denali and I have looked high and low for low point water drains for fresh water tank and the regular lines. I found one pencil thin pipe that looks like a drain under the unit near the hot water tank location. It has an off/ on valve, but when opened the water just trickles out. Any suggestions on where these drains may be located. I looked in the owners manual but nothing found on the drains. I have been able to drain the fresh water tank and the regular lines using the water pump and empting them through the hot water heater drain. This way takes for ever and I have to watch and be sure and turn the pump off as soon as things empty.

    Thanks for any advice,

    Ray Wallace

  9. Julie Rea on June 5th, 2008 10:52 am

    I always sanitize with the bleach water, then flush, each year. What about the under-sink water filter. This filter leads only to the ice-maker, and the little faucet at kitchen sink for filtered drinking water. I do not run bleach water thru those lines, but how to sanitze them? And does the filter need to be replace EVERY year? We only use those lines (filtered water/ice-maker) about 1 month each year. Balance of time we normally boon-dock so don’t use the ice-maker. Does limited use of filter make any difference in replacing it?

  10. John Spillman on July 21st, 2008 6:52 am

    I have a 1987 Monitor 5th wheel and I don’t know where the drain for the water heater is. I don’t see a plug to remove as the newer unit have. Any ideas how I can drain the water heater?

  11. Bob pierce on August 19th, 2008 4:13 pm

    Ray, try turning on a faucet inside the unit when you open that valve by the hot water tank.

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