Remove offensive odors from your motorhome’s hot water tank with this do-it-yourself solution.
By Francis & Sharon Merrow, F174520
May 2003
Water, water everywhere … and so was the water’s odor. But what was causing the bad smell coming from our faucets?
As we travel through many regions, we rely on cities, campgrounds, and water districts to filter the water coming into our motorhomes. Little did we know that simply adding an external filter between the water hookup and our coach would have prevented the offensive odor from developing in our hot water tank.
An Internet forum offered various approaches to solving the problem, but the odor persisted. On further advice from forum members, we sent an e-mail query to Atwood Mobile Products. This brought an immediate response from a representative from Atwood, which said the odor may be the result of mineral deposits.
More investigation resulted in our discovery that our water heater tank had been slowly accumulating mineral deposits over the years, because we had not been using a water filter. The tank needed to be drained, filled with white vinegar, and heated through one complete cycle. After 36 hours, the tank would then need to be flushed several times with fresh water. The process would have to be repeated in a few months if the odor was still evident. Here’s how it’s done.
Photo 1. Basic tools for the job included a crescent wrench, a funnel, and approximately 3 feet of 1/4-inch clear vinyl hose, to see what was coming out of the tank. It is not necessary to disconnect the water line from the RV, but the water must be turned off at the spigot.
Photo 2. Remove the drain plug and drain the hot water tank.
Photo 3. Once the tank is empty, replace the drain plug and remove the pressure relief valve.
Photo 4. Using a funnel, pour in 4 gallons of white vinegar. My Atwood hot water tank has a 6-gallon capacity. If the hot water tank in your coach is a different size and/or made by a different manufacturer, check with the manufacturer to determine the amount of vinegar needed. Replace the pressure relief valve and heat the vinegar-filled tank through one cycle. Let the vinegar stand in the tank at least 36 hours. If you allow the vinegar to remain in the tank more than 36 hours, you should allow the unit to cycle several times. If you opt to leave it in only 24 to 36 hours, Atwood technicians advise that it is acceptable to allow the unit to cycle continuously. When finished, remove the drain plug and pressure relief valve to drain the vinegar from the tank.
Photo 5. Flush the tank several times with fresh water to remove the vinegar solution. The vinegar taste and smell will linger, but it will soon dissipate.
Following Atwood’s instructions, I was able to get about three gallons of vinegar into our tank as I had not completely drained all the water the first time. Therefore, in about three weeks, the odor returned.
Photo 6. This called for further action. A more thorough draining of the tank using a siphon hose was necessary to remove the last quart or so of water that lay below the drain outlet. After another vinegar treatment and heating cycle, I extended the length of time for it to sit from 36 to 72 hours.
To further eliminate the vinegar odor in the RV, I had to drain and siphon all of the vinegar from the tank. I reinserted the siphon hose, constantly moving it around to make contact with as much of the bottom of the tank as possible. The siphoned contents revealed sand, sea shell particles, and mineral deposits in the bucket.
Photo 7. After numerous flushes and siphoning over the next few days, there was an accumulation of more than 2 cups of debris.
The last step was to insert a 3/8-inch garden hose into the opening from which the pressure relief valve had been removed. Water was then turned on full force to give the inside of the tank a more thorough cleaning, and the process continued until no more debris was detected.
Before draining the tank, protect the side of the vehicle with plastic or something similar. Vinegar is an acid; it will attack the finish, trim, graphics, and wax on your prized possession. A little time invested now will save heartaches and money later.
Atwood’s maintenance instructions recommend that RV owners flush their water heater on a regular basis. Full-time RVers may need to flush the system with fresh water every couple of months, especially if traveling in an area with substantial amounts of minerals in the water. The average RVer should flush his or her tank twice a year. In addition, always filter the water coming into your RV! It will improve the flavor of the water and remove debris that may be in the water pipes of the campground, before it gets into your tank. Following these procedures will help to extend the life of your water heater.