Sewer Smell in Bathroom

[Croaker]

We just got this new trailer and our first day using it. We ordered the nice Maxair fans which we are very happy with.

So...taking a shower on the first night, turning on the fan. So nice...except suddenly a really bad sewer gas smell comes into the trailer. This smell cannot be coming from our new trailer since neither tank has anything in it except a small amount of clean water. We wondered who was dumping that smelled so bad? We went out and walked around the trailer to see if anyone had spilled sewer or was dumping. There was no smell outside. We came back in the trailer and the smell was really, really bad. In the bathroom and back bedroom.

I finally figured what the smell was coming from. When we have full-hookups, I always open the gray water tank to drain into the dump. While taking a shower, and with all of the windows closed, the Maxair fan creates enough vacuum to suck the sewer gas past the one-way air trap under the bathroom sink.

OK. That makes sense. So, now what???. I just closed the dump valve to the gray tank and.... problem solved....except now I have to crawl down and dump every other day.

Thinking.....thinking. Why don't the RV parks have P-traps on the sewer ???

Wait for it.....wait for it....

Make my own P-trap.......problem solved.

Now I can leave the gray dump open and run the fan without sucking in that awful gas.

[beerbuggy]

Thanks for this. We had the same issue this past weekend and I couldn't figure it out. Does the knink in the sewer line cause any issues... like backing solids up? I would think so, but not an expert for sure.

[bob caldwell]

It's being used for the grey water.....

[kc5mhb]

Don't forget you also have a sewer vent that exits the top of your trailer. When you flush and have your black water tank closed and fantastic fan on; it will do the same thing. I don't always run with the black water open but seeing the photo, I just might try that. So yeah, with the tank closed and fan running, when you flush, the fan will pull air back through the vent and up through the toilet. I just tell the kids to turn the fan off and then flush.

[OldCoot]

Never leave the black tank valve open or you will end up with a brown mound. We never leave any tank valves open. We can go at least 5 days on all the tanks and sometimes a full week. Don't like venting a campground sewer system thru my trailer regardless of a having a slinky hose P trap outside.

[beerbuggy]

Originally Posted by bob caldwell

It's being used for the grey water.....

But it all goes down the same hose.

[beerbuggy]

Originally Posted by OldCoot

Never leave the black tank valve open. We never leave any tank valves open. We can go at least 5 days on all the tanks and sometimes a full week. Don't like venting a campground sewer system thru my trailer regardless of a having a slinky hose P trap outside.

I think that's a better idea. I could just dump daily or something. I closed them on our last day to build up some to help with the flush.

[Rupkin2]

Originally Posted by kc5mhb

Don't forget you also have a sewer vent that exits the top of your trailer. When you flush and have your black water tank closed and fantastic fan on; it will do the same thing. I don't always run with the black water open but seeing the photo, I just might try that. So yeah, with the tank closed and fan running, when you flush, the fan will pull air back through the vent and up through the toilet. I just tell the kids to turn the fan off and then flush.

Never, leave the black open for any length of time, you could be in a world of hurt down the road.
Even dumping the black daily is not advisable, reason being you need that water/liquid to move solids and TP out of the tank, otherwise it can stick and solidify thus creating a wall or jamming your valve.

To each their own but I really don't see the purpose in leaving the grey(s)open.
If you use lots of water when flushing the black then the tanks will roughly, I say roughly fill at the same time, therefore dump them at the same time, black first, then grey(s).

Like I say to each their own and if the P trap works for you then great, after all your doing this for your not me.

John

[KDHfan]

Originally Posted by beerbuggy

But it all goes down the same hose.

I think he meant that they use this for the gray water only. When it comes time to dump the black tank, they lift the hose, eliminating the trap.


2015 Coachmen Apex 288BHS
2014 Toyota Tundra 5.7L CrewMax

Sent from my iPad using Forest River Forums

[BamaBob]

Originally Posted by Rupkin2

To each their own but I really don't see the purpose in leaving the grey(s)open.
John

The only time you should consider leaving your gray valve open is in you have a Washer installed and are doing laundry.

Other than that, like all the others have said "Keep 'em Closed!"

[Croaker]

Originally Posted by KDHfan

I think he meant that they use this for the gray water only. When it comes time to dump the black tank, they lift the hose, eliminating the trap.


2015 Coachmen Apex 288BHS
2014 Toyota Tundra 5.7L CrewMax

Sent from my iPad using Forest River Forums

Yes. Thanks. I guess I left out that detail.
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.
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[sfsgm]

Originally Posted by kc5mhb

Don't forget you also have a sewer vent that exits the top of your trailer. When you flush and have your black water tank closed and fantastic fan on; it will do the same thing. I don't always run with the black water open but seeing the photo, I just might try that. So yeah, with the tank closed and fan running, when you flush, the fan will pull air back through the vent and up through the toilet. I just tell the kids to turn the fan off and then flush.

Yes, this is what I'd check, too. It would be odd coming from a new trailer but it's something to remember even if it isn't the problem this time.

[jrmartin67]

I also recently was told by a friend that he was getting a bad smell and discovered dirt daubers had built a nest in the vent pipe and thus plugged it up. Unplugged it and all was well.

[bob caldwell]

Don't forget about the black tank air admittance valve, usually found inside bathroom vanity, as a source of 'smells'.....

[Croaker]

It's not from the black tank, it's from the gray tank....but, yes. That is where the gas was coming in.....fixed with the "Slinky P-trap"

[Myrle]

Originally Posted by Croaker

We just got this new trailer and our first day using it. We ordered the nice Maxair fans which we are very happy with.

So...taking a shower on the first night, turning on the fan. So nice...except suddenly a really bad sewer gas smell comes into the trailer. This smell cannot be coming from our new trailer since neither tank has anything in it except a small amount of clean water. We wondered who was dumping that smelled so bad? We went out and walked around the trailer to see if anyone had spilled sewer or was dumping. There was no smell outside. We came back in the trailer and the smell was really, really bad. In the bathroom and back bedroom.

I finally figured what the smell was coming from. When we have full-hookups, I always open the gray water tank to drain into the dump. While taking a shower, and with all of the windows closed, the Maxair fan creates enough vacuum to suck the sewer gas past the one-way air trap under the bathroom sink.

OK. That makes sense. So, now what???. I just closed the dump valve to the gray tank and.... problem solved....except now I have to crawl down and dump every other day.

Thinking.....thinking. Why don't the RV parks have P-traps on the sewer ???

Wait for it.....wait for it....

Make my own P-trap.......problem solved.

Now I can leave the gray dump open and run the fan without sucking in that awful gas.

I never dump every day, I let mine get at least 3/4 full or when I am ready to leave. Reason if you leave your black tank valve open the water will drain ahead of waste and paper eventually it will build up and really be a problem getting out. Let the treatment tabs do their job and break the waste down.

[Croaker]

I don't leave the black tank valve open...just the gray....until the last day or two. Then I close it and use the water to flush the sewer hose after dumping the black water tank.

[tkarper14]

Croaker, first I want to say I think you have a good idea with the "Slinky P-Trap" and I may use your idea myself. We are seasonal campers and leave the grey tank open all the time because that is what works for us.

But, I think you may be addressing a symptom not the cause. Odor should not becoming through the air valve unless something else is wrong. Actually any negative pressure caused by the fan should be making the seal tighter and the odor should be less likely to come through. (Unless the membrane is torn or dirty.) So, while taking a shower today, I noticed a slight odor myself and I may have noticed it before but over looked it. Thinking of your comments, I checked my valves under the sink. Both valves were only screwed in about 2 threads with a minimal amount of sealant. I think it would be easy for odor to be pulled through the threads. I hand tightened them about 5 more turns and I will see what happens. If that does not work, I will try to add more sealant. It may be worth checking yours.

Anyway, thanks for the idea. You helped at least one camper.

[Croaker]

TKHarper14,

Good point !! I was thinking the negative pressure was forcing the membrane open. But you are right, it shouldn't do that.

Still could be a defective or just a cheap air admittance valve that doesn't seal....or gas escaping from somewhere else ??

Now you redirected my thinking......problem not solved.

[Wolverine 1945]

Originally Posted by KDHfan

I think he meant that they use this for the gray water only. When it comes time to dump the black tank, they lift the hose, eliminating the trap.


2015 Coachmen Apex 288BHS
2014 Toyota Tundra 5.7L CrewMax

Sent from my iPad using Forest River Forums

But would you not want a fair amount of gray water to flush your hose after you flush your black tank ???

If it were me all valves would be closed !!!