I am trying to add a new bathroom in the attic for kids.

Here is idea 1, my doubt is that could I join the toilet drain into the laundry drain? Does that cause any issues like the smell?

I am new to DIY but would like to learn new things. I believe that the laundry rain pipe and main stack pipe would be connected somewhere in the ground of the basement. I plan to take hot and cold water lines also from the laundry room to the attic.

Please help with any insights or ask me any questions for clarification.

My rough diagram of the plan

  • 1
    What size is the "laundry room pipe" and what is now connected to it / what do your propose to add to it? Proper traps and venting deal with smells, but verifying adequate capacity is a concern.
    – Ecnerwal
    Commented Dec 8, 2020 at 2:11
  • Hi, laundry room pipe is 4 inches wide and presently have laundry machine's drain only.
    – NIT_GUP
    Commented Dec 8, 2020 at 4:56


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