Dear RV Doctor:

Replacing the standard motorhome sewer vent with a product such as the Xtreme Vent can help to eliminate odor when traveling.

I recently purchased a 2003 motorhome. I have emptied the black water holding tank and noticed we still get a bad odor when driving. I do not notice the odor when the unit is parked. Do you have any suggestions on how to correct this problem?
Elaine Horton, Elk Grove, California

The first thing you should do is fully flush out the holding tanks with copious amounts of fresh water. Keeping them rinsed after each evacuation will help minimize holding tank odors. You state that the tank was evacuated but do not mention whether you’re adding fresh water afterward. Also, if you’re not yet doing so, add only enzyme-based tank additives to help break up the solids in the black water holding tank.

Probably the best thing you can do to eliminate odor when traveling is to replace the existing sewer vents on the roof with a product such as Xtreme Vents, available from Coil n’ Wrap (www.coilnwrap.com). These aerodynamically designed roof vents capture the breeze when the RV is standing still and take in ram air while it is being driven. Xtreme Vents operate on the Venturi principle of air being passed over a tube. As air passes over the open end of the vent pipe, it draws air and odors from the tank. This will help eliminate odors by literally “sucking” them out of the tank. This is extremely helpful, especially when a 14-inch roof vent is located very close to the sewer vent. The Xtreme Vent should eliminate issues caused by this design that shows up on some floor plans. And remember, there are just as many odors emanating from the gray water holding tank as the black tank. I consider this vent one of the best add-on components available.