We have been traveling south with our 40' Newmar Mt. Aire for 5 years. This is the first year we have experienced a sewer smell inside the RV when the air conditioners are on. First thing we check is the gas stove, but that isn't it. My husband usually connects the sewer hose, but closes the drain on the sewer and gray water and only dumps when needed. We have done this for years without a problem. We have dumped water down the stool and drains, but hasn't helped. Also, have added some liquid smell deterent, but it doesn't help. Any idea what is going on? When the air goes off, it's gone. Why now and not before?

Did you check the air admittance valve under the sink(s)?

Have you checked/ replaced the filters on the A/C? You may have something setup that is creating a low preshure in the coach pulling air back through the traps.Bill

gbopp wrote:Did you check the air admittance valve under the sink(s)?That's the most likely answer for your situation. AAV's are readily available at home improvement stores, and don't cost a lot.

Could the AC possibly be sucking the smell out of the vent / breath pipe on the roof? Don't really see how the smell could be coming from the traps. they should be full of water. Unless one has a leak in the elbow. And the smell should not come out of the stool if it is holding water in the bowl.

Air Admittance Valves. Lowes , Home Depot about $ 6.00. Buy a couple so you have a spare.

sewer smell in rv | Good Sam Community

Ro646a
Explorer
May 14, 2018
Our former Newmar motor home had a felt like material on the floor of the fresh water tank bay. Water would condense on the outside of the tank and wet the felt material causing mildew odor.
Robt65
Explorer
May 11, 2018
I also had a really putrid smell coming from mid coach and it turned out to be a house battery that had overheated a cell and I was sure it was a dead cat or varmint of some kind that crawled into the coach and died. Replaced House batteries and no more smell.

robt65
RVER
Explorer
May 05, 2018
No P trap in my toilet and the pedal stuck in up position and I hooked up to the water at campsite and flood in Bathroom and living room and then out the stairs. SO NO Ptrap in my toilet that someone described as an overflow valve. NOT!!
Goldencrazy
Explorer
May 05, 2018
I assume you have looked underneath and there are no drips revealing a leak. In my 2016 winnebago the washer was plumbed to black tank. The entry to tank was low-too low- and it would backup leaking a bit where the hose went into the drain. Once i figured out problem-smell-the fix was easy. Never do laundry without black tank valve open. A long shot but you might open areas where a tank or pipe could leak and let your nose guide you. For me small back flow just soaked. Took a major for me to discover and then a lot of gloves, paper towel and bleach. Traded for a DP.
mtofell1
Explorer
May 04, 2018
Tinstar wrote:
mtofell1 wrote:
Tinstar wrote:
Most RV toilets have a P trap in them

Huh? Every RV toilet I've ever seen drops straight into the poo lake. This is why there are flappers that seal after you flush and we use chemicals to reduce the smell. RV sinks and tub/showers have P-traps like homes. Home toilets have P-traps built in. RV toilets? Nope, no trap. At least they don't clog :)

I've only had three different RV toilets and seen a few dozen. They all had a P trap. Granted, it's only a small plastic tube and is there as a safety overflow in case the toilet is slowly leaking water into the bowl. When it gets to the top, the water will overflow through the P trap instead of on your floor. If that plastic pipe gets dried up, the smell has a direct route to the inside of your RV. You might want to look at yours again. I believe you may find yours also has it.

What you're describing is not a P-trap. It sounds like an overflow of some type. A drain/waste trap is a slug of water sitting in a cupped section of pipe to stop the smell of sewer from getting into an area. RV toilets don't have them. Sinks and tub/showers do. For the purposes of this thread what you are talking about could be causing an odor but it's not a trap. RV toilets don't have traps.
Tinstar
Explorer
May 04, 2018
mtofell1 wrote:
Tinstar wrote:
Most RV toilets have a P trap in them

Huh? Every RV toilet I've ever seen drops straight into the poo lake. This is why there are flappers that seal after you flush and we use chemicals to reduce the smell. RV sinks and tub/showers have P-traps like homes. Home toilets have P-traps built in. RV toilets? Nope, no trap. At least they don't clog :)

I've only had three different RV toilets and seen a few dozen. They all had a P trap. Granted, it's only a small plastic tube and is there as a safety overflow in case the toilet is slowly leaking water into the bowl. When it gets to the top, the water will overflow through the P trap instead of on your floor. If that plastic pipe gets dried up, the smell has a direct route to the inside of your RV. You might want to look at yours again. I believe you may find yours also has it.
Trigger_Happy
Explorer
May 03, 2018
Did you find the problem?
Bikeboy57
Explorer
May 03, 2018
You might want to take a look at the inside coils on the ac units. They do get wet and can grow all sorts of science experiments.
mtofell1
Explorer
May 03, 2018
Tinstar wrote:
Most RV toilets have a P trap in them

Huh? Every RV toilet I've ever seen drops straight into the poo lake. This is why there are flappers that seal after you flush and we use chemicals to reduce the smell. RV sinks and tub/showers have P-traps like homes. Home toilets have P-traps built in. RV toilets? Nope, no trap. At least they don't clog :)
RVER
Explorer
May 03, 2018
WE had same and I think it was the trap in kitchen sink was emptying while driving so now we travel with a cloth in the sink drain and it keeps any odors from escaping into rig. Also put a new vent topper on that spins with the wind but do not think that helped much. For us it was the GREY water and not the Black water even though it smells like Black water. Stinks!!

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