1.5" horizontal run, change to 2"? Ontario

[Ivan Blackford]

Hi All,

I'm writing about a home in Ontario. I have a bungalow with a 1.5" drain run, about 40 feet long. Here are more details:

-About 6ft from the main stack is the horizontal wye connection to the bathtub (also 1.5")
-The kitchen sink is at the end of the 40ft run, with one 90 degree bend in the path
-The kitchen has a single large sink, and a dishwasher
-The horizontal run is prone to clogging, largely because the ABS is unsupported for some of the length, and it sags (this will be fixed). Also...the occupants put stuff down the drain that they ought not to...but we can only fix so much..haha.
-The original copper drain section to the bathtub is clogging, and I plan to replace this with ABS, as well as fix the pipe support issue.

Questions:
-Can the entire horizontal run be replaced with a 2" run? the run is roughly split 60/40, with 60% being from the stack to the 90 degree bend, and the remaining from the 90 to the 90 that goes to the sink drain. The 60% section is most accessible, and I would like to replace this with 2" pipe.
-if the pipe can't be converted to 2" legally for the sink run, can I replace the ~6ft shared (tub and kitchen sink) section with 2" pipe?

 

[John Gayewski]

Yes your can replace it. But it also need to tie into a 2"or larger pipe. You can't flow from 2" into 1.5" anywhere. So it'll have to be 2" all the way to the stack and the stack needs at least a 2"inlet.