Plumbing issue.

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Bugford

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Joined
Sep 15, 2018
Posts
163
Location
Hamilton Ohio
While taking a shower, our kitchen sink started filling up. The shower drain did not back up, and the grey tank was near empty. And a couple of others times while taking showers, the kitchen sink seemed to have a large bubble burst up from the drain. Also, there is a leak somewhere beneath the floor that seem to coincide with those events. There is no leak anywhere inside the trailer. Tomorrow I'm going to cut open the underbelly cloth and try to find the source of the leak. But does anyone have ideas as to what is going on? Thanks in advance.
 

JudyJB

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Jul 6, 2010
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2,191
Might be my problem, based on the large bubble. I had the same problem last January, and got it fixed. What happened was that the vent pipe had slipped farther into the grey water tank, effectively plugging it up, so that only a limited amount of water would drain out. When the shower pan would start to fill up, I could hear loud gurgling and bubbling from sink drain. Eventually, the shower would drain, but it would take hours. When I opened the grey water tank drain, water would gush into the sewer pipe, but the same thing would happen again. Luckily, I am currently in a full-hookup site so I can do this often.

The mobile technician pulled the vent pipe up a couple of inches, but did not have anything with him to fasten it in place. I have been driving in Ohio for the past few weeks on really bumpy roads, and I am now having the same problem. Going out of the country on Sunday, but when I get back, I will get someone to pull vent pipe up and screw it in place this time.
 

Jim18655

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Joined
Nov 27, 2017
Posts
222
Sink vent should only let air into the system. I think the vent is plugged and the displaced air from the grey tank is pressurizing the system and pushing the water out of the sink trap. Why not the vanity sink also is another question. Maybe that has a leaking auto vent that lets the air out slow enough so it doesn't bubble out.
 

Ex-Calif

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May 15, 2020
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3,077
Location
NorthCentral Florida
Sink vent should only let air into the system. I think the vent is plugged and the displaced air from the grey tank is pressurizing the system and pushing the water out of the sink trap. Why not the vanity sink also is another question. Maybe that has a leaking auto vent that lets the air out slow enough so it doesn't bubble out.
I like this theory that the water coming in the sink is the P trap water. I can't see the shower water getting into the sink bowl without overflowing the shower trap. The plumbing from the shower to the grey may be long enough to mask the possible venting problem.

Curious about the water leak - Is it near the shower or the galley?

It's possible the shower piping has a slip joint or other joint that is not glued and sealed. It would make sense that if the grey vent was the problem, the water would back up in the shower pipe exposing the point where there is a gap, failed joint or damaged pipe.

My wild guess is that this is likely right under the shower drain and that's why you don't see the water come up the shower drain.
 

Jim18655

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Nov 27, 2017
Posts
222
The sink to the tank pipe might not leak except under pressure. Normal gravity flow might not have enough pressure to force the water out of the joint. But if there's a leak I wouldn't think the air could pressurize the drain to push trap water up into the sink. Might be two different problems.
 

Henry J Fate

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Jun 14, 2018
Posts
1,979
Sink vent should only let air into the system. I think the vent is plugged and the displaced air from the grey tank is pressurizing the system and pushing the water out of the sink trap. Why not the vanity sink also is another question. Maybe that has a leaking auto vent that lets the air out slow enough so it doesn't bubble out.
Correct. It will allow air in so as to protect the p-trap water. The p-trap water is needed to prevent waste odors and gas from entering the living space. This protection is usually only activated during a dump of waste water if the vent is overwhelmed, clogged or possibly a full tank. The tank will start looking for alternative air intake and waste lines become victim.

Air being forced out of the tank could put enough pressure to push p-trap water into a sink which typically is about 2 feet higher than the shower/tub drain. It gets a little tricky for that to occur but very possible. The vent that protects the trap water would remain closed and the air pressure will push as far as it can.
 

Kirk

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Oct 30, 2005
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2,764
Location
Full-time , Escapee
Since the sink is physically higher than the shower pan, gravity would not account for what you have going on. I'll be very interested to heat what you find as I have never heard of your problem before.
 

Bugford

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Joined
Sep 15, 2018
Posts
163
Location
Hamilton Ohio
Okay, I've checked the vents on top for both the black and the gray tank and those are clear I'm not sure if the fresh water tank has a vent there is a vent under the sink cabinet in the kitchen that does have a vent and it looks fine to me no blockage or anything.
I've let the bottom completely drain out and dry and today I put water in the kitchen sink, and it drained easily. Then I did the same two the bathroom sink and the shower, still no leakage. anywhere.
I'm wondering if the stop valve to the pump is the problem, but I can't seem to find it. When I'm hooked up to city water it seems like I'm getting water into the fresh water tank. Do you think that could be it? Any help is appreciated.
 

Martian

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Dec 4, 2021
Posts
82
Location
Independent Republic of Horry
Seems like you have two issues. A bad check valve in the pump would let water into the fresh tank but there is no connection between the fresh tank and your drains other than what comes out of the taps and that becomes drain water. When you get the vent pipe pulled back up the easiest way to keep it there is a good stainless hose clamp. Make sure it is not too high as that might pull it right out of the tank and create another issue.
That vent under the kitchen sink cannot be looked at to determine if it functions. Remove it and test it or replace it with a true residential one.
 

CharlesinGA

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Oct 6, 2017
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1,130
Location
50 miles south of Atlanta, GA
I'm wondering if the stop valve to the pump is the problem, but I can't seem to find it. When I'm hooked up to city water it seems like I'm getting water into the fresh water tank. Do you think that could be it? Any help is appreciated.
This issue is not related to any drain stoppage or back up......... however it is extremely common, probably gets asked on here at least a couple of times a month, numerous Youtube videos on this.

Basically a check valve in the pump is not seated properly or has some amount of "trash" in it keeping it from sealing.

The usual cure is to disconnect any city water supply and with water in the fresh water tank to draw, open the faucets and turn the pump on and allow it to run continuously for a couple of minutes. After that, turn it off and NEVER turn it on when city water is connected. Re connect your city water and see if your fresh water tank fills back up, it should not. If it does, your pump is probably beyond help. 9 times out of 10 what I described fixes the problem.

Also, make sure you are using a good pressure regulator set to no more than 50 psi on your city water hose.




Charles
 
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