Grey tank stinks really badly

[stevennlv]

(Third time the charm? I keep getting errors. Edit: OK, this asinine, it wouldn't post the first two times b/c the original title was: "Grey tank smells like feces".)

We bought a used unit less than 6 months ago. After we had been in it a while I figured out that the previous owner had not taken very good care of it and I've had to do a lot of small corrective maintenance. So this may be an issue that developed over time and started before we got the unit. We did not have this problem when we first got in to it. So, maybe it's my fault, IDK? All I can say is I've done everything I can think of to maintain my systems and one of the things I had to do was clean a stalagmite out of the black tank.

I've got a broken neck and movement is very limited, so is hand strength, lifting capacity and the ability to crab up under stuff. I'm also full-timing in a park where my wife is work camping enough to cover both of our hours and they do not allow major maintenance. So suggests like "drop the grey tank and gut half the plumbing" won't help.

FYI, I keep my grey valve closed and treat it like a holding tank. Please don't give me a bunch a flack about it. (People on the web tend to get nuts over stuff like that. I really don't need to hear it.) After a lot of reading and my own experiences I decide to do it this way. In this unit, for reasons that I don't understand, the traps do not function as I expect and smells can get from the grey tank in to the living space. Now granted, I'm not a plumber, or even all that handy, but I thought the whole point of a trap was to prevent out-gassing? (So I really don't even understand why I'm having this problem at all. Shouldn't the traps prevent the stink from getting out of the tank and in to the living space.) I've found that in this unit the out-gassing problem is way, way worse when the grey valve is open. With the grey valve open when we run water through a trap I can only compare the escaping gasses to something really disgusting like maybe taking a straight hit off a sewer pipe bong. Before the tank itself started stinking keeping the valve closed prevented sewer gasses from entering the living space. Now I'm danged if I do and danged if I don't. Open it and I get the out-gassing when the water is running. Close it and I get the out-gassing when the water is not running! But, the stink coming off the tank while pretty bad is not quite as bad as the stuff coming out the sewer with the valve open.

The problem with the tank stinking has only developed in the last few weeks and just keeps getting worse. When we first started closing the grey tank valve to prevent out-gassing while running water I was using a mix of bleach crystals, Calgon, laundry pods and black tank pods to control odor / growth in the grey tank. It worked, but we were going through a lot of money running so many chemicals through the tank b/c we end up dumping the tank about every other day. So I changed things up trying to save money and used less chemicals, but never stopped treating the tank entirely. Although I did quit adding bleach as the park asks us not to due to them employing a leach field.

I'm at my wits end here. I've tried everything I can think of. I've gone back to regularly using a lot of chemicals to treat the tank, even though it's expensive. I even used a 4x shot of bleach (enough to treat 140 gallons) and even that did not kill the smell.

I've got a jug of actual “grey tank deodorizer” on the way from Amazon.

As stated: I am no plumber at all. And b/c of my neck I've been reluctant to start ripping on the plumbing. But the problem is getting bad enough that it's time to start looking at that. The traps look OK? I mean they look like every other trap I've even seen: a pipe with a U bend in it. Could it be that they are not deep enough? Should I look at maybe swapping them out for a deeper trap? I can't get to the one under the tub. But the wife should be able to swap the ones under the sink.

The kitchen sink is the worst offender, although all three drains do it. Would cleaning the kitchen trap help? Should I maybe look at some kind of drain screens to catch food when we're washing the dishes?

I'm also worried that there maybe some cross contamination between the black and grey tanks. Ever since we bought the unit it looks to me like the plunger on the black valve will not seat completely in to its socket; meaning when the valve is “closed” there is still about 1/4” of the push rod exposed. My RV experience is very limited. But, it seems like most of the ones I've looked at expose none of the push rod when closed fully. I've done everything short of hitting it with a hammer. It is as closed as it is going to get. But, I left some as yet unused water in it the black tank and no water in the grey when we moved the unit to test my theory about it not sealing all the way. When I pulled the cap off the end of the pipe I got a big gush of water. So, obviously the black valve is not holding in water in transit and AFAIK it should. After all, a lot of black tank cleaning methods tell you to do some travelling with a little water and some cleaner in the tank. (I did that in our old unit and did not get a big gush when I pulled the end cap.) I'm wondering if I've got black water leaking and getting in to the grey tank since I use it as a holding tank. I'm not able to, nor in a place where I can, drop the black valve to replace it. Is there anything other than hitting it with a hammer that I can do to try to get it to close more fully?

Any help appreciated.

Thanks.

[korbe]

Appreciate you coming back here and posting the "before and after". Wish more folks would do that. Enjoy.

[stevennlv]

Just an update for anyone facing similar issues:

We're going to be parked for an extended period of time as I convalesce from injuries. So the vent pipe getting road rattled back down in to the tank is not an issue right now. We wrapped some duck tape around it to keep it from sliding back down. We'll see if that holds up to travel in a year or two.

I'm not going to try to tackle sealing the vent inside the tank. Beyond my abilities at the moment. But, we almost never get a whiff of stink any more. And the rare times we do it's no where near as bad.

Here are some of the things I have done to help on top of all the suggestions in this thread:

I agreed with the theory posted in this thread that the last owner had left the gray valve open letting food stick to the bottom of the tank and this was the source of the smell. I figured it was some kind of bacteria / slime growing and feeding off of that gunk. Rid-X is meant to help break up that kind of stuff (as suggested in the thread) and it did. But, as I stated earlier, I added drain screens. The reason I did that was to help "starve" whatever was growing in there. The combo of Rid-X and not supplying new food worked very, very well.

I did not use the Rid-X as directed. The bottle I bought was designed to use 1/3 of the bottle every 30 days to treat a 1500 gallon tank. My tank is 40 gallons and dumped every other day. So I just poured in about 2oz (1/4 cup) every time I cycled the tank.

After cycling the tank several times that way I started to notice some really disgusting looking thick, nasty smelling grey sludge would drain out at the very end, like it was coming out of the bottom of the tank.

I figured the Rid-X was doing it's job and I'd help things along a bit. So I pulled a hose around through the door, ran it in to the sink and went through 8 or 10 cycles of filling up the tank and draining it. And some really horribly disgusting stuff came out of the tank.

Also, with the way my plumbing runs I only had two of those vents everyone informed me of, not three. So now I have a spare. I ended up having to change the one in the bathroom too. But, I didn't get on hands and knees to see where stuff ran before I bought two more vents. It turns out that in my bathroom the sink and tub share one vent. So, make sure of how many you need before you head off to the hardware store.

And, just to help out those even newer to this than me I want to share some of the things I have learned on this project:

When I purged the tank with the 8-10 refill / flush cycles I closed the drain vent so the tank would fill. But, we don't want to overfill it and have it run back up in to the tub.

Most "standard" water hoses are just slightly larger than 1/2 inch. I always use a pressure limiter on my system to keep my systems from being over pressured.

https://www.amazon.com/Camco-40055-Brass-Pressure-Regulator/dp/B003BZD08U

So, we have a hose slightly larger than 1/2" and a pressure around 40-50 psi. According to the googles that means we will be moving about 25-30 gallons a minute. And since most grey tanks are around 35-40 gallons I would recommend timing the fill up with a watch and not letting it fill for much more than 60 seconds before opening the drain valve.

And now not only does it not stink inside anymore, but when I go out to drain the tank I don't get a blast of gross, disgusting, make you want to puke stench. It just smells like dishwater.

Hopefully some of this will help the next person.

Thanks to everybody who helped me.

[myredracer]

One solution to the tank valve is one that twists on to the existing outlet, like the Valterra #T58 in the photo. Could be just temporary until you get the original valve issue fixed. The original valve seal could need replacing or it could have something blocking it and preventing it from fully closing or it may need some lube. If you don't have an enclosed underbelly the valve is easy to get to.

Air admittance valves (AAV) are notorious for failing and is usually the first suspect. It does sound tho. like the vent pipe has dropped or is plugged. P-traps never need refilling after a dump. If the vent pipe is plugged, air will get drawn through the sink (or shower) drain and empty the traps of water during a tank dumping. I'd suggest getting a quality commercial grade AAV like an Oatey #39017 as in the photo - $15 on ebay or $30 at Lowes. We had an AAV fail on our new TT at under one season. Got a replacement and that failed soon afterwards so then got the good Oatey one and has been fine ever since.

Sounds like your tanks could do with a cleaning with an RV tank cleaning product or maybe the Geo method. Liquid Drano will work great and is safe on plastic and metal and is what our owner's manual says to use. Normally you would drive around to let the tanks slosh around so not sure how effective any cleaning product will be if stationary but should be better than doing nothing.

[GaryKH]

Whatever you do, get someone to help you with the contortionist poses! You have to treat your neck as the number one priority! I am coping and adjusting to this after my neck was missing a vertebrae , and i was in a rigid collar for 1/2 year(last year). Just 2 days ago, i went to do some job that required me to get down on my knees, and twist my head to see something. I just couldn't do it. After a curse and a prayer, i went and found someone else. They enjoyed helping me and i got to keep a relatively pain free neck!

[Community Alumni]

following

[down_home]

Anything is possible from a lot of food debris and grease and the tank not rinsed good or at all.
If it is not a vent it may be that.
We wash cloths and use softener and shower with gel and shampoo.
We do not let any grease into thee tack with exception of minute amounts, and of course dish washing soap.
I would fill it by washing clothes and showering etc about 3/4+ full, maybe add some water softener and bleach perhaps. Drive it down a long bump road and go though the fill and flush. If that don't get whatever is in there than a long wand on a power washer up the drain maybe. 🙂

[Bobbo]

stevennlv wrote:
She also reported that the grey tank vent pipe was able to be pulled up by about 1/2 an inch and that the cap for that pipe was on so tight that no air flow would be allowed.

DING DING DING!

Your vent pipe has come loose and slipped down into the tank. Its bottom is now under water and can not vent anything. It needs to be pulled back up as high as it can go and be anchored there so it can't slip down again. You probably also need to get to the place where the vent goes INTO the tank and seal around the vent pipe so odor doesn't seep out around the pipe.

[stevennlv]

OK, I misunderstood, I thought there was only one. If the problem continues I will change the ones for the bathroom sink and the shower too. (There are two access panels for the tub plumbing that are screwed shut that I haven't opened yet, hopefully the one for the tub would be behind one of them.)

But, so far, so good. I sent the wife up on the roof. She reported that both roof vents pipes were clear when she shined a flashlight down them. She also reported that the grey tank vent pipe was able to be pulled up by about 1/2 an inch and that the cap for that pipe was on so tight that no air flow would be allowed. When she pulled up the pipe for the grey tank we got a big stinky "burp" out of the tank through the kitchen sink. (No sound, just a lot of really bad smell.) When she put the cap back on she left room for airflow.

We replaced the kitchen vent. I think it was the worst offender. I haven't smelled anything since it was replaced.

I got a bottle of Rid-X with 3 months worth of standard treatments in it. I'll cycle that through the grey tank until it's gone.

I checked the p-traps. The kitchen was dry. I always fill it up after dumping the tanks, even though that was not necessarily the purpose of what I was doing. I was just running water to get deodorizers in to the tank. I haven't dumped the tank in a day or two. Since we are in Las Vegas I'm thinking that maybe b/c it's so hot/dry that trap is drying out. I'll keep an eye on it. I called the guys that make the waterless trap. As is I don't have enough room to fit one in to the existing plumbing in the kitchen. I'd have to cut some pipes and so forth to get one to fit. I'll jump off that bridge if it comes to it.

I've already had to clean a "pile" / stalagmite / whatever out of the bottom of the black tank. Just FYI, one of the guys in the park here had it done here the fast way by a service and it cost him $175 total. I went with the slow method. From reading one line, supposedly the fast way has the potential to damage your systems. I know the guy who had it done here had to sign a waiver that the company was not responsible for any damage. The slow way is not hard to do. It just takes a few weeks, some cleaners, some driving and one of those spray in to the bottom of the black tank hose pipe adapters. Total cost was less than $40 and a little time.

I really appreciate everyone's help, info and quick responses. I learned a lot.

Thanks everybody.

---

Edit:

Oh, and I added one idea of my own. I got those screen mesh drain filters for the sinks to help prevent large food particles from getting in to the grey tank to begin with.

[ScottG]

Another possibility; are you sure it's coming from under the sink?
If not, they sometimes "hide" another vent, this one for the tank, inside the fridge area. Rather than run the vent through the roof. they simply run it up to the fridges roof vent.
If you have a cabinet under the fridge you can sometimes see the pipe coming up through the floor.
I suspect a smelly tank could get through the sides of the fridge and stink the room up.

[doxiemom11]

Deleted - wrong tank

[Bobbo]

My Airstream trailer has 3. There is 1 under the kitchen sink. There is 1 under the bathroom sink. There is 1 behind the shower on the shower drain.

[coolmom42]

stevennlv wrote:
OK, I cross replied with some folks and I see now from other that this things is under the sink. I got under there and looked and we have one. I'll replace it. I'll also get some rid-x, but what about the roof vent: just check to make sure it's unobstructed?

Edit: OK, that one was answered too while I was crawling around under the sink. Thanks everybody. I'll go through the list and report back.

There will be one under the bathroom sink and also under the kitchen sink (assuming you have both.) One per sink.

[ScottG]

Those "air admittance valves" are notoriously bad. So bad that the one they normally use (like in Dutchmans post) are not allowed in your home by code. There are better ones available like this one that are allowed by code.

[sdianel_-acct_c]

We use 1 cup of Dawn Platinum dish detergent and one cup of powdered Borax dissolved in the bathroom sink full of hot water after we dump and rinse the tank. Usually no odor. We did not use our washer/dryer combo for a long while and we did get an odor coming from there. Just added water to the washer and put it on spin and no more odor.