MA BA tub draining into basement floor drain

Hello all, thanks for viewing this post.

Inspection today- when the MA BA tub was engaged and draining there appeared to be no issues. Until i went to the utility room and noticed that the floor was all wet. With my partner working with me, we diagnosed it to the MA BA tub causing the moisture.

Usually the water heater pan would be lead to drain into the utility room floor drain, along with the HVAC condensate pipe (s). There were 3 pipes leading to the basement floor drain. 2 from what i mentioned above, and the third from an unknown source.

Please help me figure out what the third pipe is from. Because that is where the MA BA tub was draining into ultimately leading to the basement floor drain and not the plumbing pipes we normally deal with.

Is it improper piping? A clog in an air pipe?
Your time is appreciated.
The pipe that is connected to the MA BA is the far left of the three pipes leading to the floor drain.


Some pictures related to what you’re talking about would help your in your questions.

Thanks, just did.

Yes it’s improper. The third pipe looks to be 3/4” and a minimum tub waste is 1-1/2”. A tub is already trapped and dumping into another trap, this would be a double trap. A floor drain is not meant to pick up a tub waste. The tub waste should be piped directly to the DWV system.

Are you sure that 1-1/2” pipe going into the ground is not the tub drain? If it’s piped too close to the floor drain it may cause the floor drain to back up. There may be an obstruction in the drain slowing the flow and causing the floor drain to back up. All this doesn’t mater to you. The floor drain is backing up when the tub is ran. Put it in the report and refer it to a plumber. Let him figure it out. A simple ear on the pipe when the drain was running would isolate the proper pipe.