No, I am not talking about the campers parked next to you. I am talking about odors coming from the gray water and black water tanks. In earlier posts I told how to sanitize black water and gray water tanks. However even the cleanest tanks will smell rather quickly. Most people, when at a campground, leave their gray water dump valve open. While this is an accepted practice it does allow soaps and other organic matter to collect on the bottom and sides of the tank.
As all gray water connections are protected by P-traps the only way smells from the gray water tank can get in the coach is either through a dry P-trap (found under sinks and under the shower pan) or the Foote vent becoming defective. A Foote vent is a piece of white pvc pipe with a white mesh that covers openings in the sides near the top. Inside this vent is a one way valve that allows air into the drain pipe system but will not allow air out of the pipe system. They are found under sinks where a vent stack cannot be used because of conditions in the construction of the camper. If all P-traps have water in them and the Foote valve is operating properly you might have a cracked pipe above the point where the sink drains connect. If it were below these connections you would have a water leak every time you used the sink or shower and it would be easy to find.
Gray water smell is not at all like black water smell. If you have a black water smell (you know that smell from dumping the black water tank) the toilet is probably the offender. It usually is the only thing plumbed into the black water tank. The most common part that fails on the toilet is the tank flush seal. The easiest way to see if it is still viable is to add water to the toilet ( a quart will do) and if it is still there a few hours later the seal is still good. The next area to check would be the toilet seal to the toilet floor bracket. In home toilets a wax ring is commonly used but in an RV they use a rubber seal. Because rubber will dry out and through movement there can be gaps between the seal and flange and/or toilet base this is the first thing I would replace if the tank flush seal checked out okay. I have only seen one instance where a vent pipe had separated from the tank and odors were coming into a fifth wheel this way.
I don’t sell products so I will not name any brands but there are vent stack covers you can buy from the major camping discounters that replace the flat plastic covers on the pipes currently. These new covers create a vacuum as air passes over and around them to help pull gasses out as you are traveling and will also work with a slight breeze when you are stationary. I had one camper that had a bad black water smell. We checked everything we could and it turned out wasps had built a nest in the vent for the black water tank on the roof and every time you flushed the toilet gasses would come out while the toilet valve was open. This will happen when the water drops into the tank and the air it displaces has to go somewhere. Every situation is different but this information should get you headed in the right direction. Next week I will talk about batteries….