Sewer Smell from Vent under RV Sink

by Al

How to Get Rid of the Sewer Smell from Your RV

How to Get Rid of the Sewer Smell from Your RV

My 2008 Salem kitchen sink does not have an outside vent. It is vented under the sink with a flapper-type vent. When I leave the gray water open, it fills the camper with a sewer smell....what is wrong, and what can I do other than keep that closed all the time. When I leave the gray water open, I don't open the black water.

ANSWER: Hi Al, the vent that is under your sink is known as an Air Admittance Valve, it is also known as an inline vent or cheater vent. It is used in some RVs and Mobile Homes in place of a roof vent.

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When you drain water out of your RV's sink, the draining water creates suction (vacuum effect) on the valve, which then opens and allows air in the pipe, which in turn allows the water to drain freely. When the water is done draining, the valve is supposed to close tightly and seal out any sewer smell or, in your case, gray water smell from coming in the RV.

Based on your description it sounds like your valve is not sealing properly and may need to be replaced. Replacing this valve is fairly simple in that in most cases the valve just screws onto the pipe. All you will need is a big pair of slip joint pliers to help unscrew your existing vent. To install it all you do is put some Teflon Plumbing Tape on the threads of the new valve and tightly screw it on.

Look at the video below to learn how these vents can start releasing a sewer smell in your RV.

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360 Siphon RV Roof Vent Cap

The odor you smell from the gray water tank is usually from decaying food particles in the gray water itself. You might want to also start using some Enzyme Holding Tank Treatment in both your grey and black water tanks. The enzymes in these treatments digest waste and work quite well to minimize holding tank odors as well as being environmentally friendly.

IMPORTANT NOTE: If you have replaced the Air Admittance Valve and you still have a sewer-like smell in your RV, you should check the compartment where your RV's House Batteries are stored. Your house batteries could be low on acid and/or boiled out from overcharging. The boil out or low acid can produce a strong sewer-like smell in your RV.

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two types of AAV vent
by: Kay

Thanks for the great video and explanation. I learned a lot from it, and we replaced both our AAV's in our fifth-wheel trailer. I just wanted to make your viewers and readers aware that the plumbing in RVs can be of two types. In general, with motor coaches, you have PVC plumbing, while in pull behind trailers they use "ABS". And the two are NOT interchangeable, not inter-mixable. PVC is thicker-walled. ABS is thin-walled. We ran around the area to RV and plumbing supply places and finally ended up ordering from the company whose name is on the actual valve. In our case "Ayrlet". Thanks again for all the help that your website provided. I appreciate it.

draining sink in kitchen
by: Anonymous

I have changed both the traps under the kitchen sink and bathroom sink and the water still does not drain well

Air admittance valve, in-line valve
by: Geo

These vents shook loose on my rig and fell out. I go a lot of miles. I recommend sticking your hands down there after 5000 miles and tightening them up regularly.They are under sinks and hiding in walls but they should all be accessible.

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