Hello,

My sink in the main bathroom stopped draining under gravity. Maybe somebody can give me some advice...

The house is old (from 196x). There are 2 adjacent bathrooms.
Bathroom 1 has sink #1, bathtub and toilet #1.
Bathroom 2 has sink #2, shower and toilet #2.

Main sewer line runs directly to where the bathrooms are located. So the pipes from bathrooms sinks to the sewer pipe must be short. I have not inspected the pipes in the crawl space under the house, but they must be short.

1. It looks like main/sewer line is OK.
Bathtub, shower, sink #2, both toilets and kitchen sink are draining fine. I occasionally have problems with tree roots in the sewer line, but it was cleaned not too long ago and it seems to be OK.

2. Sink #1 was draining slowly and it was getting worse over the last month.
I disconnected the union in the elbow trap under the sink and cleaned the elbow and blue pipe coming from the sink. No effect.

3. I ran a 25ft snake through the elbow under the sink a couple of times. All 25ft went in.
Then I connected the elbow back and noticed the water was not draining at all. i.e. it got worse.
At this point I decided it might be a problem with the air vent.

4. I got on the roof (1 story house) and found 3 vents - about 1-1/2" or maybe 2" pipes right above the bathrooms.
One vent (lets say vent #1) is right above sink #1. I ran the same 25ft snake through all 3 vents (twice through vent #1). Every time all 25ft went in, The end of the snake was wet every time I pulled it out.
The vents are probably shared between two sinks, bath tub and shower, but I don't know exact configuration.
Cleaning the vents did not help. The water was still standing in sink #1.

5. I connected a clear hose above the elbow under sink #1.
i.e. I installed the elbow back, but did not connect the blue pipe coming down from the sink.
I connected a hose instead of the sink pipe. The other end of the hose I connected to the faucet and let cold and hot water flow. The water was draining fine under pressure for long time. i.e. the pipe after the elbow is not clogged. The water is not coming out of the roof vent so it must be flowing to the sewer.
I disconnected the clear hose from the faucet and raised it above the sink. Most of the water in the hose drained under gravity, but not all. The water in the hose stands about 10" above the sink level. If I poor more water into the hose, it drains under gravity to that level and sits there.

Any idea what is going on and what I can do to fix it?
I suspect the air vent #1 splits into two pipes. One goes to sink #1 and the other maybe to sink #2.
Maybe the vent section that goes to sink #1 is clogged. When I ran the snake through the vent on the roof, it probably went to the section that goes to another (working) sink #2.
Does it make sense?
If it is the case, I don't know how to fix it. I can pump water under pressure to any opening (elbow or vent), but if the snake goes through, then water will also take the same route and will not clean the clogged section.

Thanks,
Mike

You do not have a functioning vent for that sink since the trap weir is higher than the wall inlet. Although an S trap would still drain unless something else is happening. You might have a grease blockage that has hair and shampoo skin products forming a blob of slimmy gunk blocking the pipe and your 25' snake just poked a pencil size hole in a grease ball the size of a soda can and upon withdrawal the grease just reform a few inches further down and seals off again. What kind of snake? Did you use a drop head? What if the snake did not go down the drain but went up the vent instead not knowing how they all got connected with what kind of fittings.

ditto


onsite plumber required

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

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You do not have a functioning vent for that sink since the trap weir is higher than the wall inlet. Although an S trap would still drain unless something else is happening.

Thank you! I might need to replace the trap since it is old and the union leaks water.
If I understand correctly, I should put a P-trap there and the bend should go below the wall inlet. Unfortunately there is not much space below the wall inlet. I might need to cut an opening in the wooden cabinet shelf to have space for the U-shaped bend.

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You might have a grease blockage that has hair and shampoo skin products forming a blob of slimmy gunk blocking the pipe

It makes sense! Every time I pull out the snake, it smells like a nice shampoo. I expected a different smell from drain pipe.

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What kind of snake? Did you use a drop head?

Husky 1/4" x 25 ft Drum Auger. The tip is just a spiral of about 1/2". Not a drop head.
I will have a different powered snake and drop head attachment by this weekend.

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What if the snake did not go down the drain but went up the vent instead not knowing how they all got connected with what kind of fittings

It's possible. 25ft Snake did not come out of the vent opening on the roof, but I am not sure it went to the sewer either.
Is it common for an air vent to be shared between two sinks ?
If the vent is only connected to one sink, I should be able to clean it.
Each bathroom has a sink, a bathtub or shower and a toilet. But there are only 3 air vents on the roof above the bathrooms. So maybe they are shared.

I will try to fix it myself this weekend one more time.
I will have an inspection camera, a pressure washer with long hose and drain cleaning jet nozzles and a different snake with drop head.

Thank you!



Edited 1 times.

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Is it common for an air vent to be shared between two sinks ?
If the vent is only connected to one sink, I should be able to clean it.
Each bathroom has a sink, a bathtub or shower and a toilet. But there are only 3 air vents on the roof above the bathrooms. So maybe they are shared.

When you say "share a vent" it kind of depends on the context.

Yes it is quite common say you have a bathroom with his sink and her sink side by side, the vent could be in the middle and one sink connects to the left and one to the right. Or you may have two bathrooms and the configurations are like a mirror image so you can have sink A in bathroom A and sink B in bathroom B run to the same vent/drain. The tub/shower and other fixture can also share the same vent by running their own vent vertically up the wall, but turns and joins the sink's vent at say 48" above the floor, or even higher in the attic. You may even have a first floor fixture's vent goes up to the second floor and ties in at a point above those fixture's flood rim elevation. They are all sharing a vent in that case. There is also wet venting where the entire bathroom group is sharing one vent. No telling how your's are all connected.

Thanks a lot!
My sinks are in different bathrooms and at least 10 feet away from each other.
I will figure it out. I also have a camera now.
Thanks again!

Vents are also oftentimes combined in the Attic to lessen the number of roof penetrations.

Thanks!
It looks like in my case they are joined closer to the floor level.

I ran a powered snake 3 times through the sink drain pipe and watched on camera as it came out to the main line. No sign of debris of any kind. Unfortunately I couldn't get the camera into the sink pipe. Only to main.
Next I put the camera into the vent and the vent was completely clear all the way down to the main. However, there are two T-connections (90 degrees) in the vent and I couldn't get the camera or snake into these side connections.

Then I was thinking.. If the water is standing in the sink, it is probably also standing in the drain pipe and possibly water is touching the vent pipe (the bottom of the vent pipe), Maybe soap and hair clogged the vent opening in the drain pipe (the bottom of the vent where it meets the drain pipe),
So I bought a gallon of Drano Max Gel and forced it into the drain pipe. It worked after 30min! The problem is gone.
I don't usually use these chemicals and I never believed they actually work, but I am glad I tried this time.

sulfuric acid WILL dissolve body oils mixed with shampoo and hair

BUT

if it does NOT work you then have a pipe filled with battery acid

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638