New construction basement toilet plumbing not flowing

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BDK

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Dec 6, 2019
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Location
Macomb, MI
Hi,

I'm trying to help my son finish his basement on a new house (built 1 year ago).
3 stubs were plumbed for the basement bathroom. Our initial activities:
1. Shower drain was capped (no shower being put in)
2. Sink drain was cut to place vanity (temporarily taped top until final plumbing and keep drain flies in)
3. Toilet drain was cut to install toilet after flooring. PVC was 3 inch schedule 30, so used an inside 3 inch twist in flange so floor would not need to be busted up.

Toilet was installed. First flush was great. Subsequent flushes don't go down, water just rises in bowl. Bowl water eventually goes down after several minutes.

A week later (we work on it on the weekends) we got around to finishing the plumbing for the sink.
We left toilet issue alone, as we thought it might be a venting issue, which we hoped to resolve by installing studor value on the sink for venting.

Tested toilet again and same as last time. First flush great again. Subsequent flushes don't evacuate water from bowl. Water just rises in bowl. Recedes to normal bowl water level after several minutes.

Ran water in newly plumbed sink, and after a couple minutes, sink lines back up and water begins actually rising in the toilet next to the sink.

Does this indicate a clogged line, or still a venting issue?

In another section of the basement, we installed a kitchen area with sink, and plumbed that into a floor drain. We are having no issues at all with the water draining for the kitchen sink.

Any next suggestions?
 
Snake the toilet drain all the way to main sewer or sewage sump pit.

Is there a sewage pit?
Is there even a pump installed?
 
Jeff - thanks for the response.

Tomorrow morning I am going to remove the toilet and try snaking, like you suggested.

The home is within a good size city (city water and no sewage pit). I'm assuming the plumbing in the basement just runs out to a normal sanitary sewer.

The basement has poured cement walls before we finished it. In the cement basement floor were just the 3 stubs for sink, toilet, shower. No additional vent stacks or lines visible anywhere else in the basement for these.
 
Also snake out that floor drain you tied into, as far as you can get.
If the floor drain is gone now, snake through a clean out if one exists.
 
Don't you have a vertical drop from the plumbing above?

Any idea if the basement kitchen sink drain ties into the main drain closer to where it would be exiting the house? I would think it would be, if that's running fine.

Do you know which side of the house the main drain would be exiting?

Those existing stubs with no vent doesn't sound so good. I can't wait to hear how you make out with the snaking of that line.
 
Last edited:
Yes, there has to be a vent there, for that bathroom rough-in.
Maybe you covered it in drywall and then forgot about it?
If there is no vent, everything will clog.
And the traps will get sucked dry when water runs down the drains.
 
No vertical drop from the plumbing above (not in the area for the bathroom stubs are any ways).

I'm assuming the sink drain does tie to main drain closer where it exits the house.

My plan from here is:
1. Remove toilet and try snaking from there. If that don't work...
2. Lift tile where clean out is by kitchen sink that works, and try snaking from there.

Will let you know how I do. Thanks for the feedback.
 
Post some pics close up and wide view of the bathroom area plumbing.

You might have to bust the floor and add a vent.
Even to add a cheater vent AAV, which still will be totally wrong but might work well enough.
 
Well, no shower and sink has an AAV.
The flow from the sink going into the toilets 3" line will likely have no effect on the toilet trap.
Not sure how a ventless 3" line will handle a 1.6 gallon flush.
A 3" line with 1/4" slope can handle roughly 25 gpm when only half full, so it may work out anyway.

So long as that line gets cleared and/or connects to something.
 
Are you planning to snake BACK from the kitchen cleanout? Is that possible?

So the vertical drop from the floor above may be hidden behind a finished wall?
 
Would be nice to call someone with a sewer camera while the toilet is off to inspect the line from the toilet out to the main to make sure there’s no issues
 
Definitely camera the line. It might not be tied in to anything. The whole toilet vent thing is a urban legend. Three inch pipe and for sure four inch pipe has the cross sectional area to take a 1.6 gallon flush. And, the sink and kitchen are tied in and will act as vents for the main line.
 
BDK said:
Hi,

I'm trying to help my son finish his basement on a new house (built 1 year ago).
3 stubs were plumbed for the basement bathroom. Our initial activities:
1. Shower drain was capped (no shower being put in)
2. Sink drain was cut to place vanity (temporarily taped top until final plumbing and keep drain flies in)
3. Toilet drain was cut to install toilet after flooring. PVC was 3 inch schedule 30, so used an inside 3 inch twist in flange so floor would not need to be busted up.

Toilet was installed. First flush was great. Subsequent flushes don't go down, water just rises in bowl. Bowl water eventually goes down after several minutes.

A week later (we work on it on the weekends) we got around to finishing the plumbing for the sink.
We left toilet issue alone, as we thought it might be a venting issue, which we hoped to resolve by installing studor value on the sink for venting.

Tested toilet again and same as last time. First flush great again. Subsequent flushes don't evacuate water from bowl. Water just rises in bowl. Recedes to normal bowl water level after several minutes.

Ran water in newly plumbed sink, and after a couple minutes, sink lines back up and water begins actually rising in the toilet next to the sink.

Does this indicate a clogged line, or still a venting issue?

In another section of the basement, we installed a kitchen area with sink, and plumbed that into a floor drain. We are having no issues at all with the water draining for the kitchen sink.

Any next suggestions?
Click to expand...
There should be a backwater valve installed in this drain. You should check that
 
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Diehard said:
He'll find out when he snakes it!

Why "should" there be a backwater valve?
Could that be a "may be"?
Click to expand...
If it’s a year old and was installed during the build it was required to protect it against backup
 
@turd, would it still be a basement if it is above the manhole cover?
 
@BDK, while most of the comments here are sound, you indicate that this is new construction (1 year old). In that case, the first thing I'd do before snaking, cameras, etc. is call the builder in and have him explain the venting on this. If the builder is arrogant or won't help, go to the city who issued the permits and ask the plumbing inspector; he is the one who approved this new construction and you'd like to know how the venting is supposed to work. Once that is sorted out, maybe the problem will once again fall in your lap and then these suggestions about snaking, cameras, etc. will be useful.

Just because it's new, and approved, doesn't mean it was done correctly--with or without an approval stamp. Get to the bottom of that first.
 
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