Sewer smell when draining kitchen sink

[Jimalberta]

Hi all....we get a horrible smell of sewer when we drain the kitchen sink. I have looked through this forum at other posts and find a reference to an air admittance valve. I have searched every inch of my drain pipe from the sink and there is no air admittance valve in my unit. Could this possibly be a mistake from Heartland? We generally have our outside door open with the screen door closed and I'm wondering if a gush of sink water down the drain would create enough pressure to make the roof vent spew out the smell. Anyhow its bad and we usually have to open windows and the door and turn on the fantastic fan to get rid of the smell.
We keep the tank valves closed at all times except for dumping.

Is it possible that the gray tank has a bad build up of something in it for this kind of smell to exist? If that can happen is there a good way to sanitize the gray water tank?

lots of questions....sorry

Jim

 

[cookie]

Unless someone removed it, you should have one.
It should look something like the one in the attached picture.

Peace
Dave

 

[ChopperBill]

We had a smell around out kitchen and when I went to find out about it I unscrewed that breather valve and it stunk so bad I thought I was going to vomit. Poured a bunch of bleach down the sink and the smell went away. We always put a couple of cups of bleach down it after dumping now.

 

[Noobie]

On our coach I find if I'm running the overhead fan as I'm dumping the coach gets a nasty wiff so we make sure to turn it off first

 

[Jimalberta]

Dave....I definately don't have one of those and there is no indication that one has been removed. I am baffled.

 

[Jimalberta]

ok...update. I found one of those Air Admittance valves under the bathroom sink. I followed the kitchen sinks drain all the way to the outside wall and at that point it tees and goes down and up. Right above where it goes up inside the cupboards there is a vent on the roof so I'm assuming that this is the gray water vent but they must have decided to eliminate the AAV because it apparently is not needed? I dunno.

I'm gonna get a couple of those Cyclone vents and install them.

 

[evolvingpowercat]

Those air admittance valves have a one way air valve which is supposed to let air flow in but not back out. They can fail and let vapors in the pipe leading up from the grey tank into the area under your sink. If the odor is stronger under the sink when you smell it in the RV that is likely your issue.

If so, you may need to cut that air valve off and solvent weld a new one on to get rid of your issue. If the one in your RV is on a threaded fitting you may be able to unthread the top part and buy one at Home Depot, Lowes, etc. that matches and not have to go the cut off / solvent weld new one on route.

I don't think changing the grey tank vent on the roof is going to resolve your problem.

 

[Jimalberta]

hey Randy...the only problem is I don't have an air admittance valve under the kitchen sink.

 

[ncrebel8]

Jim, you are right ypur rig does not have an air admitance valve under the kitchen sink. Supposedly, (depending on the rig's plumbing), if the roof vent is plumbed into kitchen sink drain line, you theoretically dont need an air admitance valve in the drain line.

We also have had this problem with the odor when you use the kitchen sink. I cut the drain line and installed an air admitance valve under the kitchen sink, and installed new vent caps on the roof. First the cyclone vent, then I changed it to a venturi style vent that is supposed to work better. this one> https://360productsnorthamerica.com/site/ . We still have this odor sometimes.

We usually fill the grey tanks and the black tank with clorox and water if the camper is sitting here in the yard for any length fo time. It seems that after sanitizing the tank this way the odor isnt there, but it doesnt take it long to return with use. I also would love some information from anyone who has found a way to get rid of this odor for good.

 

[kakampers]

We too own an '08 and do not have a valve under the kitchen sink....had the issue early on and put a rotating vent cap on the vent pipe on the roof...no more smells!

 

[evolvingpowercat]

ok some more trouble shooting thoughts...

- can you confirm that you still have water in the kitchen sink trap after running water down the kitchen sink drain ? It is best if the sanitary tee is no more than 2 feet from the trap. If not, then the water can siphon water from the trap giving the vapors a path into the sink.

- can you confirm that the drain pipe is fairly level. Too much slope makes for a trap that is not level and a bad joint at the tailpiece, this can lead to it not being vapor tight and can siphon the water from the trap as well.

- there might be a incomplete or missing solvent weld missing making something not air tight.

 

[porthole]

Our Cyclone has an AAV in the bath and under the galley sink.
Never any issues until this weekend. Had the "odor" while brushing my teeth, but not all the time. Turns out when the bath vent fan is on, vapors from the bath holding tank were being drawn through the AAV and the vanity door/cabinet interface right up into my nose.

New valves for both this week - or a plug..............

 

[vangoes]

Are these valves actually needed? They do seem to emit foul odors periodically, especially when the AC or fan in running.

 

[Rickhansen]

Mine was not sealing and stinking. I put a sandwich bag over it and duct taped it tightly as a test. The smell stopped and the bag is still in place. That was 3 years ago.

I don't think they are needed from the functional perspective, IMHO.

 

[JohnDar]

Is their purpose to act like a vacuum breaker when water is flowing down the drain to the tank, allowing air to be drawn in to promote flow? Just curious since most of the drain systems don't get a lot of gravity assist.

 

[danemayer]

I think the way it works is that as the water starts to drain, it leaves a vacuum in the drain pipe that slows the drain action and/or siphons the water out of the p-trap. A vent going up to the roof allows air to follow the draining water without suctioning the water out of the p-trap. If sewer odors make their way up the vent pipe, it's outside and above the rig. If you don't have a vent to the roof, the vacuum breaker allows the draining water to suction air through the vacuum breaker to do the same thing a rooftop vent would do. And if the vacuum breaker is working properly, it would not allow sewer air to flow the other way into the living area. But if it fails, that's a different story. Anyway, that's the way this non-plumber understands it.

 

[wsenecal]

I have a 2010 Cyclone 3010- for the last 2 years on and off, I'll get a horrible odor outside the rig by the door if someone is washing dishes. There is a vent on the roof which doesn't appear to be plugged, but the only way I've been able to work around this is by leaving the drain to that grey tank open when I'm on the road. This isn't ideal as I'm sure I've got gunk on the bottom of the grey tank. It doesn't always work either. To make things worse, the vent on the black tank seems to have stopped working as I get a big bubble when the toilet is flushed, combined with order from that as well. I'm ready to close the whole da** thing up and haul it to a repair center, but gotta believe there's a better answer.

 

[Rickhansen]

Wsenecal,

Welcome to the Owner forums, I see this is your first post.

Grey water stink is 20 times worse than black water. We too leave grey water gate valves open when camped. I hope "on the road" comment is figurative and not literal (Yuk). Every few weeks I close the valve, pour some Dawn dish soap and bleach in the sink and leave closed for a day or two. This helps sanitize and break down grease. When tank has a good volume of water in it, it will drain and hopefully take most of the sludge and solids with it.

As far as your Black tank vent, mud daubers and such can build nests in the cap and stack. I would remove the vent cap and inspect. You could also insert a garden hose into the roof vent and flush the line down to the tank. With your tank drained and dump valve open you should see water flowing to the sewer connection. This will test your theory and probably clear any blockage in the vent system.

 

[cookie]

When the toilet bubbles back at you it is normally a sign of a full tank or an obstruction in the drain pipe.
Use lots of water when flushing.
Try plunging the toilet or take a five gallon bucket of water and pour it down the toilet to hopefully clear a clog.

Peace
Dave

 

[danemayer]

We have a new owner-written Water Systems User Guide that has tips on many of the questions being asked in this thread.