Has any body ever used their sink ins ted of their toilet ?

a 3 or a 4 inch pipe goes to the septic system or the sewage connection.WHen the pipe goes in the house it is a 3 or 4 inch to the toilet.It then drops to a 1 1/4 to a 1 3/4 inch pipe that connects the sink and bathtub.This pipe them runs over to the 4 inch pipe and usually either "Ts" in or has a Y connector where it joins the sinks and tub to the 4 inch drain.SO basically if I have lost you by now, ALL these pipes join up under the house and go to the same place.You might want to run some water in the sink to FLUSH IT .....

Yeah when my wife is on the toilet,It works fine.