Plumbing DWV Question

This set up has 5 drains going to one 1 1/2" vent, and there are a lot of elbows. It consists of a washer and water softener downstairs, and a toilet, sink and shower from upstairs. I wasn’t sure if this is acceptable?

Five drains going into one vent?

Vents can certainly be combined. If I am interpreting correctly, this website(link) is suggesting that up to eight(8) 1.5" diameter fixtures can share one 1.5" diameter vent stack, provided that the total pipe length is less then 150 feet. The effect of the elbows is negligible for air movement.

1 Like

No problem.

1 Like

Ok, ya I read that in Plumbing Code, but IRC contradicts that it seems.

There is a lot more to this than just a no problem. You will need to calculate the DFU’s of all connected fixtures. You’ll need to know the total vent length, including horizontal to see if it’s acceptable.

This is most likely out of your realm, and should be out of the wheelhouse of a home inspector. If you have any suspicions about the installed system, contact a local licensed plumbing contractor.

1 Like

If you’re going to inspect new construction plumbing, it’s best to know what code book you use. I believe you are from Texas and they follow the UPC not the IRC. Read that paragraph above about staying in your wheelhouse. It may keep you out of court.


Hey Martin, do you know what this is? And Merry Christmas!


Hey Brian, Merry Christmas!

As I zoom in on my phone, it appears to be a polymer elbow.


Thanks, first time I have seen that fitting. :+1:

1 Like

I haven’t seen one for a long time. It’s a proprietary fitting that you can only use with a special tool.


Yes, it’s a press PEX fitting, and you can see others in the pic. Faster is better! you can “press” everything today, even black pipe for gas and steam, nuts! In 20-50 (and in same cases sooner) years from now many of those fittings will start leaking because they rely on a gasket instead of a mechanical/welded seal. But who cares, 50 years is good enough, right :smiley: