New construction basement toilet plumbing not flowing

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That’s correct but you don’t find a lot of basements above the manhole
I would agree to that.

In response to if it would still be a basement...
In general, the basement designation is completely independent of the the subject requirement.
It's actually the the finished floor elevation of the level containing the lowest fixture and it's relationship to the manhole.

There are designations for basement under bldg codes for fire protection and the like.
 
@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.
Excellent thought!
You must be a "Philadelphia Lawyer". :)
 
Pictorial example...

Backflow-Prevention-Illustration-Backwater-Valve.jpg
And if your piping for that lower level has a single pipe line connection to the whole house pipe before leaving the basement, than it would be best to install the backwater valve on that basement only line.

Reason: Backwater valve is not recommended if not required and in fact not allowed if not required based on what the code says.
Except for existing buildings.
 
Well I removed the toilet and tried to run a snake.

It went in pretty smooth for about 6 feet and then it sounded like it was hitting a door. I say a door, because it sounded like it would hit something the sound like a door clicking.

We did not remember any other floor access or clean outs within 20 feet. We just finished the basement, including all the flooring. Just south of the bathroom plumbing was the underneath area of where you come down the stairs and into the basement. We turned this into a small utility closet. This was the only place we didn’t put flooring. Since it was close, we looked in there and found a thin black plastic cap on the floor, almost under the last couple steps.

With a screwdriver, the cap popped off and underneath was a back valve. Problem was, it was installed backwards. Pulled the door off the back valve and all the backed up water went running through.

reinstalled the toilet and it worked like a champ.

not sure why this was in the middle of the basement, six feet from bathroom plumbing. We don’t plan on busting up the floor to reinstall the back valve properly (just put cap back on top and left it at that).

Thanks to all for your suggestions and feedback!
 
You will be sorry if the sewer ever backs up into your basement.

If your sewer line going to the street clogs up, all the drain water in the house will come up out of that black cap and flood the basement.

Ditto if the street sewer gets overloaded, or flooded with rain water from a storm.
Your basement is where that overload will go.

You should have the valve repaired.
And modify the stairs if needed, so you can remove a section to have full open access over the cover, for maintenance or repairs.
The backwater valve can fail to seal from paper or other debris catching in it.
So even after you dig it up and fix it, it should be able to be easily accessed for routine maintenance.

Much cheaper than the damage from crap water flooding your nice finished basement.

Insurance usually does not cover that sewer flood damage, unless you buy a separate rider for that.
 
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It's easy to make a case for a Backwater Valve.
Then there's the kitchen area with sink, and plumbed into a floor drain. Not sure if that means the floor drain no longer exists. But in any case that line is downstream of the existing backwater valve.
Don't know if this installation requires it by code but just as a point of interest, they apparently feel if it's not necessary based on their criteria, you're probably better off without it. As pointed out, they get fouled up and require maintenance.
Clipboard01.jpg

EDIT: If it was me, and there was no floor drain, I'd probably just make sure that cap on the backwater valve could hold back the a bit of pressure.
Either that or have a backwater valve installed further down stream where it would cover the entire lower level.
 
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We really don’t know for sure what side of the valve the sink drains into.

They probably did not have much going through that old floor drain connection.

The backwater valve might have slowly let water trickle through.

And I can’t imagine any plumbing inspection would pass a floor drain on the wrong side of it.

But then, they apparently have the bathroom rough-in without vents, so who knows?

I would at least figure out a very tight fitting plug for the cover of the backwards backwater valve.
Maybe a metal and rubber expansion type test plug, or something else that could stand some pressure.

Until the sewer backs up into the toilet or shower.

Meanwhile, the toilet drain works!
 
We really don’t know for sure what side of the valve the sink drains into.

They probably did not have much going through that old floor drain connection.

The backwater valve might have slowly let water trickle through.

And I can’t imagine any plumbing inspection would pass a floor drain on the wrong side of it.

But then, they apparently have the bathroom rough-in without vents, so who knows?

I would at least figure out a very tight fitting plug for the cover of the backwards backwater valve.
Maybe a metal and rubber expansion type test plug, or something else that could stand some pressure.

Until the sewer backs up into the toilet or shower.

Meanwhile, the toilet drain works!

Im sure the plug that comes with the bwv will suffice
 
OP said that they were having no issues at all with the water draining for the kitchen sink. I suppose it could easily be confirmed if it ties in upstream of the Backwater valve by looking into the valve when kitchen sink flowing.
 
Maybe lay a stack of heavy patio blocks on top of the cover, it couldn’t hurt.

And put a water alarm next to it, towards whichever way the floor slopes, to warn of water coming up through it.
 
Just one more thing.

The floor drain you plumbed into, for the kitchen sink, might drain to a sump pump if you have one.

So it might not even drain into the sewer line directly.
 
He might have a sump pump, I don’t think he has said he does not.

Most basements have one, in my experience.
 
Yeah I guess he could have one and not be aware of it.
That's sounds strange from my point of view but I guess anything is possible.
 
He might have one and be aware of it.

I don’t think he has said anything about a sump pump, but he might have one and know about it, and just has not mentioned it in these postings.
 
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