View Full Version : Adding an additional drain waste line to an existing line.

05-09-2011, 08:03 PM

I was hoping to get some advice and or confirmation on adding an additional drain waste line to an existing line for a utility sink in my garage. There is a 1/2 bath on the other side of the wall where I'd like to put the utility sink and I can tap in to the waste line and hot/cold water lines. The half bath sink drain is empties from a 1 1/2" line that is T'ed into a 3" vertical waste line. What I would like to do is put another T below the sink's T and would be ~15" lower. Since it is attached to a stack and won't move, I won't be able to solvent weld the new T into the 3" vertical drain line, but instead planned to use one of the rubber sleeves that has two hose clamps to secure it. Is there anything wrong with doing it that way?

The second T would go along the bottom plate at about the same level as the copper line that feeds the toilet. It would run in the same direction as the T above it.

05-21-2011, 02:24 PM
I decided to just redo the 3" line and replace the current 3"X"3"1 1/2 sanitary tee when I put in the new sanitary tee for the utility sink. With that in mind, I did notice the 3" line is reduced to 1 1/2" for the vent. But the vent at the roof is 2". That should effectively make the vent 1 1/2", which serves the toilet and sink in the half bath plus the new utility sink. Is a 1 1/2" stack sufficient?


05-21-2011, 04:49 PM
In most cases, it would be 2" for a toilet, and depending on how far away the sink is, there may be more to it than just "putting in a tee". And you should/must NOT use the rubber sleeve with two hose clamps to make the connection.