Can the laundry sink drain in the basement empty through a waste clean out? I had an idea that this is not allowed or is it just not a good idea. I only saw two other clean outs, basement was partially finished. Any help?
That’s not a clean out anymore its a Tee now 
Its still wrong, because it is wet vented and there is likely a WC above the tee and a lot of other stuff besides.
I call that unconventional plumbing should be corrected blah blah blah
Hey you stole my canned comment…
Care to elaborate? What’s the concern?
Incorrectly vented, wet vented fixture can’t be below the toilet.
You have NOT proven your case.
You are under the assumption that the posted laundry sink is below a toilet that is plumbed in a true wet vent fashion!… which requires the toilet to be downstream of all other fixtures.
A soil stack, which typically doubles as a vent stack, IS NOT considered a “wet vent” configuration.
http://www.mass.gov/ocabr/images/dpl/boards/pl/cmr-22-fig04.gif
A three or four inch cast iron stack in an obviously ancient basement, and I can’t assume there is a toilet above it or four fixtures? I guess if it was in Minnesota the toilet would be in the backyard.
Wow!
Simple question… is the OP’s post as shown (or similar) in the following graphic?
No!
Than it is NOT wet vented, so you have NO basis for your statement.
Non-issues…
Jeff, I’m not a plumber, so excuse my ignorance. Your diagram (which is a great one, btw), shows the toilet at floor level. Let’s say the OP’s toilet is, in fact, upstairs, above the sink drain connection, which is upstream, and uphill, from the basement sink. Then the sink drains into the soil stack, or stack vent, with toilet above. I would imagine one would get sewer gas in the downstairs sink that way.
Or is that what is depicted in your second drawing, with the green pipes. The upper one would have toilet emptying into it, with the basement sink below the toilet. I’ve seen it this way before, and never called it out. It looks like it doesn’t need called out, if your second diagram is the way I described?
