How do I best connect my drain lines to make the rubber-pvc and pvc-metal transitions water tight?

I've got a washer and drawer washer combo with a drain line for each. There's no vent pipe to the roof and the drain in the wall is galvanized or something along those lines.

The pvc 'solution' I have at this point is just hand tight, so water can leak a little at the pvc-metal transition and gray drain line to pvc transition. The studor vent has helped tremendously in cutting down sewer smell, but the rest of the fitting probably still leaks some sewer gas. In case the pics aren't shown, I have two gray, rubber, 3/4" diameter, corrugated washer drain lines pushed into a 3/4" x 1-1/2" slip pvc adaptor. Both of those adaptors are connected to a 3-way T PVC. A studor vent is attached via a vertical stand pipe of maybe 18" to the middle connection on the 3-way T. That 3-way is connected via a 45 degree connector over the metal drain pipe in the wall.

two drain lines connected to 3-way T with a studor vent connected to a metal drain pipe close up of 3-way T connected to metal drain pipe

1 Answer 1


Washer drain lines are not supposed to have an "air and water tight" connection - they are specifically supposed to have an air gap, or loose fit into the top of a standpipe.

The (bottom of the) standpipe should have a trap, which appears to be missing or hidden. Evidently missing, given you report stink. The water in the trap is what seals out sewer gas.

  • Thanks, I'm pretty sure you are right about the missing trap. Since it also doesn't have a vent pipe, the studor vent is the next best thing I've done to allow it to vent air in without venting sewer gas out. Opening the wall and adding a trap is kind of my last resort. I'll rephrase as I'm more concerned now with water right at the pvc-metal and pvc-rubber transitions.
    – Jeff S.
    Commented Feb 19, 2023 at 15:18
  • Put the trap on the outside of the wall, then, before you enter the trapless pipe in the wall. A studor is not a trap. Use a rubber coupling to make a proper metal to PVC connection to the pipe in the wall, and glue the PVC joints, while providing the drains with standpipes above the trap(s).
    – Ecnerwal
    Commented Feb 19, 2023 at 15:48
  • Thanks, I will do that. I don't know why I didn't think of a p-trap outside the wall.
    – Jeff S.
    Commented Feb 19, 2023 at 20:24

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