Hydrogen Sulfide Smell from Drains - BH 3385RL

Jim-n-Leslie

Active Member
Since dewinterizing (I do not recall the issue last season) I have found the smell of rotten eggs - hydrogen sulfide - from my gray water tanks. :p At first it was isolated to my kitchen sink (the previous couple of trips in March and April), but now I am having the same smell from the bathroom sink and shower. :p

It typically occurs when I run water down the drains. I verified for the sinks (kitchen and bathroom) that there is a goose neck and, when removed, it appears to be full of water. I have drained and flushed the tanks three times on my current trip - a week in Orlando FL - since there are four of us vacationing in our BH 3385RL. I have added enzymatic tank stuff to counter the smell (the bottle says it is primarily for the black tank, but can be used for the gray tank). That has not helped. I am having no issues with the black tank. :)

The tanks appear to drain fine when I drain and flush them. I have looked down the vents from the roof, but see nothing. My plan when I get home is to drop a plumbing snake down the vent tubes to see if there is anything obstructing the air flow. Do I need to be aware of any check valves or other concerns that could be damaged when I run the snake down, or is it a free drop to the tank bottom? :confused:

Last, is there anything more I can do? Since the goose-necks seem to be holding water, I doubt a deeper one replacing what is there will do any different. The lingering smell anytime water goes down the drains is making the trailer untenable. :mad: Any/all suggestions are welcome. :cool:

Thanks!
Jim
 

Ray LeTourneau

Senior Member - Past Moderator
Jim, yours is the first I've ever heard with a smell of that type. I've had the sulpher smell from well water before but never from a drain. I assume by your term "goose neck", you are referring to the P-traps. They are supposed to hold water. That's what keeps tank odors from returning to the coach. One thing to check is under the kitchen sink (at least in my rig) there should be a black 1-1/2" vent pipe sticking up and on top of this pipe there should be a threaded check valve. It's supposed to allow air down into the tank but not out. Make sure this check valve is screwed down at least hand tight and that the rubber flapper is working correctly.
I would also try a good brand of drain cleaner used as insrtucted on the label down each trap. Kitchen, shower and vanity. After using the drain cleaner, run fresh water through all the drains to rinse thoroughly. I hope this helps you out.
 

cookie

Administrator
Staff member
One other place to look is under the bathroom sink. My rig has an Air Remittance Valve under the kitchen sink and under the bathroom sink.

Peace
Dave
 
Air Admittance Valves by Studor (example - RV one is likely black, different shape and not by Studor):
studor-mini-vent.jpg
How Studor® Air Admittance Valves Work
studorventing.jpg
studorsealed.jpg
When a plumbing fixture is operated and water drains out of the system, negative pressure causes the valve to open, allowing air to enter as needed to equalize the pressure and protect trap seals from siphonage. When the flow stops, gravity closes the valve, preventing the escape of sewer gases through the valve.
Link to page

Picture of valve in RV from post by jimtoo:
mailboxtractor054.jpg
 

biddo

Member
Jim, we had a very bad odor comming from the kitchen holding tank and I had thought it was the flapper valve gone bad but replacing it did not resolve the problem. Still had the foul odor every time we ran water in the kitchen sink. The odor would escape through thru flapper valve every time we ran water. The fix for us was about a half a gallon of bleach poured down the kitchen sink. Seems as though bacteria can grow and build up rather quickly in hot weather which was causing our odor problem. We add the bleach to our tank every couple of months and have not had the problem since.

Hope this helps as the odor can make yoou not want to enjoy your Big Horn

Mel
 

Ray LeTourneau

Senior Member - Past Moderator
The valve pictured in jbeletti's post is exactly the one I was referring to. Now I know the technical term for it. Thanks Dave & Jim.
 

SmokeyBare

Well-known member
Is there a chance that your flushing the drains with HOT water and could the HOT water have an odor to it? I've had in the past smell coming from the type of water I was connected too & the fact that the Anode Rod in the Hot water tank needed replaced.

Once you've cleaned the "P" Traps, checked the Air Admitance Valve for proper operation, Flushed the tanks well, and made sure the vent pipes connecting roof top vents to the holding tanks are not blocked up. You should be good to go.

Good Luck,

Marv
 

Duramax1

Well-known member
Is there a chance that your flushing the drains with HOT water and could the HOT water have an odor to it? I've had in the past smell coming from the type of water I was connected too & the fact that the Anode Rod in the Hot water tank needed replaced.


Good Luck,

Marv

That was the source of the rotten egg smell I once experienced. The solution was to sanitize the hot water tank.
 

jmgratz

Original Owners Club Member
One other thing can cause the smell and that is leaving the tank drains open. When they are open the smell can back up into the RV. Another things I have heard of is the air conditioner bringing the smell into the RV from the roof vents. Just a couple of other suggestions.
 

fhollan

Well-known member
Glad I found this, since this is the first time that I've got this problem also. And I agree that the heat wave we've been having is a contributing factor to this problem. The half gallon of bleach just might solve the problem. As far as using a drain cleaner in the P traps, might have to find one that doesn't heat up the traps and damage them. Thanks Guys!
 

Jim-n-Leslie

Active Member
Well, first I want to thank everyone for their suggestions. I looked into all of them. I do not know if I have fixed the issue, but at this point I do not have bad smells. I will note here that although there is the occasional H2S smell, what comes from the gray tanks is more like bad onions - really bad. Just the same, I also believe that the H2S smell, in addition to the heavy onion smell, is being drawn into the trailer by the AC from the near-by vent caps. More on that later...

I did clean out the p-traps. My wife poured baking soda and vinegar down the drains - no, the system does not explode like a high school volcano. We did not use that much. It did help to clear out the drains and made them smell better. The air admittance valves are pretty tight, and I was reluctant to unscrew them from the pipe, not sure of their purpose. Now that I understand what their purpose is (I guessed, but the info posted was a great help), I will tackle them next. Although the smell has subsided, I still want to ensure the air admittance valves are working properly.

I am trying to avoid the heavy bleaching approach on any of the tanks, because I use the powered enzyme (RVtrine) and it definitely does the job with the black tank. It's just the grey tanks that are presently a significant problem. Lastly, I checked the hot water tank, and it appears to be fine. No bad smell there.

So, what I did note was that the first campground we stayed in, Santee Lakes Campground in SC, was a bad choice for a 38' long and 13' high trailer. There were too many low-hanging branches and I ended up losing two mushroom vent caps and a busted but not entirely sheared mushroom vent cap. Okay, my judge of heights and proper areas to drive my trailer still sucks - but it's getting better. I'll address our campground experience under another thread.

The entire time we were in Florida, the vent caps were open to the atmosphere. I am not a vent cap educated engineer, but I learned (through my online research) that the mushroom shape contributes to crossing breezes drawing odors up the pipe and out to the atmosphere where they belong (I seem to recall a Bernoulli effect in High School many moons ago) :rolleyes:. There are a number of aerodynamic venting devices you can install on the top of your rig to enhance this effect, but they are quite unsightly. I can see why the folks who sell these campers use the mushroom vent caps - they generally work and are more aesthetically appealing.

So, there I was this past Monday after returning home, sitting on the roof of my camper with new mushroom vent caps and one with an internal fan and a small solar panel to power it. I installed the new caps and Voila! (currently) no more smell. Hopefully the issue will be gone. We camp again in three weeks up the eastern shore, so that will be the litmus test...

Sorry about the lengthy diatribe. I just thought it might be of interest to someone. If I am off base regarding the value of the vent caps and the contribution their mushroom shape may offer the tanks, let me know. I'm grasping at straws here!

Jim :cool:
 

jmgratz

Original Owners Club Member
Jim, glad you got the issue taken care of. Somehow it always seems when people post problems they fail to tell the complete story. Had you of said the vent caps were damaged we could have led you right to the problem. But anyway I am glad that yall got the problem taken care of. Good luck and BTW watch the tree branches.LOL
 

SmokeyBare

Well-known member
As for the A/C to draw air inside the RV. There would have to be places on the Air intake side of the A/C. If the A/C is sucking air from those area above the Ceiling, that air could be getting into the attic by way of the vent holes cut through the roof, where the vent pipe and vent cover is located. An open gap around the vent pipe... allowing air to be pulled down into the attic because of those possible leaks inside the intake of the A/C could be a where your smell is getting in the coach.

There is a possibility of places above the plastic ceiling grill that could be open to the Attic area of the RV. One of place could be where the power cable runs into the A/C unit. I found a few in my BigHorn. If you feel you want to explore this thought, remove the ceiling grill from the A/C and have a look around inside. Use some foil duct tape to seal any air leaks around the intake side. Just a thought...

Good Luck !
Marv
 

RoadJunkie

Well-known member
This is a timely thread as I have a mild case of the sulfur odor that is only noticed in the bedroom when the AC is running. The odor only appears when the temperature is at the highest for the day, as well. Guess I'll take the cover off and do some sealing. Thanks for your post, Marv.
 
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