The house here in Indiana is a split level with 2 baths upstairs and a 1/2 bath and laundry room in the basement. The toilet is about 12' from where the main stack comes down and turns before heading out to the septic tank. I don't know the exact route that the toilet drain takes but it obviously connects with the main at some point under the basement floor. The main stack lines up with the cleanout in the front yard so it goes out to the septic in a straight line. House was built in 1980, all DWV piping is PVC.

There has been talk from Management about removing the 1/2 bath to expand the laundry room. The sink ties into the toilet line and both are vented via an AAV above the suspended ceiling. My question is, if I remove the toilet and sink, can I just jackhammer the concrete the short distance from the toilet flange to the wye where the sink joins in, expose the pipe, cut off the wye and glue a cap on the 3" pipe? Or do I need to jackhammer all the way back to the main and remove all of the unused piping?

I know in supply piping you don't want any dead ends where water can get stale and grow bacteria, does the same apply to abandoned waste lines? Is there an acceptable length of abandoned waste pipe?

I have ran into this a few times myself.

One time I was actually abandoning an illegal bathroom that the previous owner put in. I had someone sent down a camera with a locator and marked the lines inside the house so I know where the illegal bathroom line ties to the main. I then jackhammered up that connection, cut the connection to the main and cap right there. The rest of that line became dead on both ends and I was allowed to just abandon in place.

Another time what I did was I extended the drain to an exterior wall, and turned it into a cleanout access.

I also did similar to supply lines that are too long to abandon I think 24" is the limit, I just extend them horizontally along the wall cavity to an exterior wall and attached hose bibbs on the outside both hot and cold. Inspector was impressed.

24" IS the limit for a 'live' dead end


you MAY abandon unused open both ends (or capped both ends) under the slab

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

how many homes in the US have underground piping roughed in for a future bath ?

over the years i have roughed many, many. above ground and below ground. probably all of them longer than 24 inches
none of my former customers have died of the plague.

Packy, LOL I can almost guarantee that this house was built like that and the basement was finished after CO was issued and taxes assessed.

Sum, that's a good idea using a camera to find where it ties into the main and excavating/disconnecting there. If I cap it right after the wye that leaves a de minimis stub off the main. and the rest can be abandoned in the floor.

Thanks for the info guys!