simply put, I am renovating my bathroom, and when i removed the 'original vanity, I found a confusing thing, I grabbed a video and put it on youtube.
[ame]http://www.youtube.com/watch?v=48eLRsgsmsg&context=C31c515dADOEgsToPDskLWXyE_uxMJ9dqexMOHvi6l[/ame]
The one pipe that comes straight off the vent is the only drain that enters the main stack the other pipe (on the left) goes straight through the basement floor, and all the house sink drains are connected to this one
[ame]http://www.youtube.com/watch?v=48eLRsgsmsg&context=C31c515dADOEgsToPDskLWXyE_uxMJ9dqexMOHvi6l[/ame]
The one pipe that comes straight off the vent is the only drain that enters the main stack the other pipe (on the left) goes straight through the basement floor, and all the house sink drains are connected to this one