When piping in a bathroom with sink drain toilet and shower where do you locate the vent?

You normally locate the vent at the sink drain, but you can locate a vent at every fixture if you like.

Answer*The sink is vented above the tee holding the trap arm to the sink. The sink drain will go below the floor and be joined(usually with a wye) from the shower drain which then is joined into a wye from the toilet drain. You can also use a double wye from the toilet drain to pick up the sink on one side and the shower on the other. Maximum length from the shower to the wye should be 6 feet. The vent from the sink will suffice to vent the whole bathroom group! Look at the top left on page 56 of the following web page I just looked up for you:

google.com/books?id=ZpEkoie_SqgC&pg=PA54&lpg=PA54&dq=bathroom+group+venting&source=web&ots=p4nzF98-Dc&sig=B_6T06oVxbJkQySNTBvk0U3KMLg&hl=en&sa=X&oi=book_result&resnum=3&ct=result#PPA56,M1">http://books.google.com/books?id=ZpEkoie_SqgC&pg=PA54&lpg=PA54&dq=bathroom+group+venting&source=web&ots=p4nzF98-Dc&sig=B_6T06oVxbJkQySNTBvk0U3KMLg&hl=en&sa=X&oi=book_result&resnum=3&ct=result#PPA56,M1

* Cheers, QuiteSomething

the vent starts above the flood level rim of the sink not the tee. it all depends on how it is piped for the vent. if you can wet vent it than you will only need one vent off of the sink but most of the times its just easier for a home owner two install two vents one for the sink and one for the toilet and shower, but make sure the vent for the toilet and shower comes off in between the two fixtures for it to be vented correctly. then just bring the two vents above the highest flood level rim and pipe them together