Return to the Plumbing Forum | Post a Follow-Up

venting washer drain

Posted by cakie (My Page) on
Mon, Sep 20, 10 at 17:23

Do I have to vent a washing machine drain? There is room around where the washer drain hose fits into the 1-1/2" drain pipe for air to be pulled in when the washer drains. But I am not sure what plumbing code requires.

Thanks for holding my hand through this re-plumbing of my daughter's old bungalow.

Follow-Up Postings:

RE: venting washer drain

"There is room around where the washer drain hose fits into the 1-1/2" drain pipe for air to be pulled in when the washer drains."

That has nothing to do with plumbing venting.

Venting is to allow the water to flow in the waste lines without creating suction that could empty the traps used to keep sewer gas from entering your house.

You know that gurgle the toilet makes as it flushes?

That is desired in that case sine the water in the bowl is restored as the tank fills.

If that happens on other drains there is nothing that will refill the trap.

RE: venting washer drain

The washer might, depending on the applicable code, be able to vent with a Studor vent. Check the code for that specific location.

RE: venting washer drain

There are many rules about venting under each of the plumbing codes.
It is not easy to advise.
After (downstream of) the P trap at the bottom of the stand pipe, a vent is required under every code I know of.
Other rules apply too.
For example, there are limits on what other fixtures' drains can be plumbed onto that same Trap arm.

A washer's stand pipe is an "open" drain which will gurgle.
It must be open. Not closed.
This is entirely not the same thing as a vent.
A vent (in DWV terms) is always on the downstream side of the P trap. has forums for various plumbing codes.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Plumbing Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here