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Old 06-16-2013, 09:57 PM   #1
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Sewer odor...sometimes

We just bought a 2005 Itasca Horizon. After sitting on our driveway for a few days while working in it, we notice a sewer odor. We thought it was coming from the kitchen sink, but now it seems that when we turn on the AC it smells throughout the coach. We don't smell it in the toilet area and we don't smell it all the time. Can anyone help?

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Old 06-16-2013, 10:22 PM   #2
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Try adding water to all drains include the sinks, showers, wash machine anything that drains into the holding tanks. The gray holding tanks can smell just as bad as the black tank. If the P traps go dry the smell can travel through them into the RV. I would also pull off the inside grill of the A/Cs to make sure they are not leaking. My A/C produces a lot of water through condensation might want to check there it is draining to.

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Old 06-16-2013, 10:24 PM   #3
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Thanks! I was just reading some of the older posts. We're going to try some things out tomorrow.
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Old 06-16-2013, 10:28 PM   #4
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So . . . have you filled the toilet stink traps with water?? i.e. via the toilet overflow holes?

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Old 06-16-2013, 11:29 PM   #5
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Xtreme Vents Odors can come in from the roof, we added some of these to our roof vents to flow air away from being returned into the MH. It happens when you run a fan or the A/C because the pressure changes slightly inside and draws odors down. These have been very effective and very durable.

Also if you have a W/D make sure the pee trap is full by running a load, odors can be draw out of the grey tank into the coach when you run A/C or a fan as well.
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Old 06-18-2013, 09:22 AM   #6
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I chased this smell earlier this year only to find out if was a battery going bad and off-gassing.

Also RVs use an anti-siphon valve in the vents. They use a spring loaded rubber flapper, if this goes bad, it will smell with all the traps full.

If you have a washer/dryer, don't forget that P-trap.
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Old 06-18-2013, 09:36 AM   #7
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Other ideas...

Could it be the battery off-gassing? If not a sealed type, it can make a rotten egg smell sort of like sewer odor if it's old and is dead or dying and the charger keeps trying to charge it. Or if it has been installed backwards like what happened to a friend of ours camping right next to us. Kept thinking someone was spilling black or grey water on the ground. Sniff around the battery. Or disconnect and see if it goes away.

Black or grey water tanks or fittings can occasionally leak because a crack has developed or something has come apart so check for water underneath or soggy feeling underbelly or insulation.

Don't forget to post what you find (or else).
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Old 06-18-2013, 09:51 AM   #8
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A dry P-trap or an anti-siphon valve is the most like offender but if your kitchen sink is in a slide, manufacturers get pretty "creative" with how to connect the moving slide to the static plumbing line. You might take a hard look at how your kitchen sink drains into the grey tank---just guessing....
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Old 06-18-2013, 10:20 AM   #9
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I just went through that and here are some ideas from my troubleshooting.

1. I had a P-trap for a previously installed Washer/dryer that I think was dry. We kind of thought the utility closet it was in was funky smelling. Added water to trap and that helped in that specific area.

2. During light winds we noticed sewer smell in different parts of the MH. I think what was happening is that the light winds directed the odors to one side or the other. When running our Fantastic fans we learned to close the windows on the opposite side of the MH from the wind.

3. Do NOT run fans in the coach if the windows are closed and you flush the toilet!

4. Even with all windows open and both Fantastic fans running, we run off the one in the bathroom when flushing...also close that window if it is open.

That has seemed to fix our problems.
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Old 06-18-2013, 10:41 AM   #10
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If you are using draining your tanks on a fairly frequent basis and still have this level of oder--something else is wrong. Suggest a thorough tank cleaning and then switching tank de-oderizers.....
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Old 06-18-2013, 11:03 AM   #11
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Our coach has a vent pipe that probably extends way too far down into the grey tank andf does not function as a vent when the tank is dumped after it has been completely full. The outgoing water has to be replaced from some source and that source of air are the bathroom sink and shower as well as the washer/dryer "P" traps.We must cycle the W/D wash the shower stall and wash hands at the sink to replace the water in the traps. We all know why the shower needs to be washed and the hand washing is manditory!
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Old 06-18-2013, 07:52 PM   #12
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I kept smelling what I thought was sewer but after some investigation I found that there was a small leak in the stove. I tightend the connections and no more odor. Propane smell is almost like sewer.
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Old 06-19-2013, 07:32 AM   #13
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Add a Cyclone vent to your outside vent pipe. I've had 3 Winnebago's and all had the same sewer smell problem until I added the Cyclone and the smell went away. Available at Camping World for $20.00 or on line.
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Old 06-19-2013, 12:50 PM   #14
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Ditto the Cyclone. The things being called anti-syphon devices are actually called under cabinet vents, and they do wear out after a while. You can get them a for a few bucks at a home improvement store. By the way, if you use your kitchen a lot and the gray water tank has been standing for a while, it can smell about as bad as the black tank. We usually put a little anti-stink chemical in the gray tank if we are going to be sitting still for a while.

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