In our master bath we have a sink, toilet and double sinks. We keep getting backup from the toilet and cannot use the sinks or tub as they will not drain. Does not show any slab leakage, but can't seem to know why the toilet backs up constantly, have had plumbers out 3 times and all they do is snake the toilet to unclog it, but it still returns. They say we have an illegal bullnose "t" connected in the slab that is probably blocks and can't snake it because it is a 90 degree angle not at a slant and we may have to completely jackhammer out all concrete to redo plumbing. Can you provide any insight or help and thanks. When you run a snake from the tub drain iit goes up the vent pipe, snake from sink it goes out the tub drain (weird).

Kay Cox

I've posted a pic of a bull nose tee. Its basically a straight tee(non directional), and should never be used in drainage(especially under ground). The only real use for these in a drainage system would be as a cleanout when placed in the vertical.
I would suggest having a see snake camera sent down the toilet drain to see what is under the floor. You may be able to just break up a small portion of the floor and fix the problem area. Hopefully there is only one of these in the system and you won't have to replace all pipes underground. Let us know how things go.

Bull nosed tee, sometimes called a " Vent, Inspection or Clean Out Tee" has no curved throat to direct the flow. However even if the tee is bull nosed gravity alone should complete the drainage. Get a sewer cam down there and see where the clog is,
Your plumbers don't what you have under the slab. Why don't they snake from a roof vent? Until you know what you have you can't make a repair . Good luck, Tom

If both sink and tubdrains are also affected by this then it may be more than a bullnose tee problem, and did this just start happening? How long have you lived in this home? Either way I third the advice to cam the line. Goodluck.---zeke---