Return to the Appliances Forum | Post a Follow-Up

dishwasher/sink flood

Posted by randekasp (My Page) on
Tue, Nov 16, 10 at 12:21

I posted this in plumbing as well, hope that is OK. Until I am clear about how "loop" is, I am wondering if it is safe to use the diswasher itself. Here is the post and brief followup:

New dishwasher installed last year without airgap. Think/hope contractor used the "loop" system discussed elsewhere on this forum.
Suddenly, WITHOUT dishwasher running, water from sink went to bottom of dishwasher, did not drain, but ran out bottom of dishwasher onto floor. Sears came out (does anyone else now believe that Sears is beyond terrible?) Technician said nothing wrong, guaranteed that an undercounter airgap will resolve issue. I read here never to do that. So.... Any ideas appreciated. Thank you.

"high loops" are often configured improperly. My new DW with "professional" install was botched this way. Knowing what to look for, I fixed it myself. Very easy. The peak of the loop must be secured above the level of the sink-lip....right up there under the counter. However, even then, if your sink is really full the surge from opening the drain can push water over the high loop. Once that occurs, the siphoning can continue until the sink's empty. I suspect that's what happened. An air-gap installation will prevent this. That's why many people have suggested that ALL codes, not just some, should require air-gap installs.

Your dishwasher will not drain unless the drain pump is operating. Once the siphoning action began, you were doomed unless you recognized it and stopped the drain immediately.

"The peak of the loop must be secured above the level of the sink-lip....right up there under the counter."
Securing it to the bottom of the counter (and making sure it stays there) is all that is required.

While it could still cause a backup if the sink is filled to overflowing, kitchen sinks are not normally filled that high.

The important thing is to get the loop high enough that normal use of the sink never allows water higher than the loop.

Follow-Up Postings:

RE: dishwasher/sink flood

You can run the dishwasher. Your problem was a surge from the sink beginning siphoning down to the dishwasher. If there's nothing to cause that siphoning to begin, you'll be fine. In other words, just keep the sink empty until you have clarity.

RE: dishwasher/sink flood

Thank you!

RE: dishwasher/sink flood

If your plumbing can accommodate it, you can also use a separate stand pipe with the dishwasher output hooked into it just as most clotheswashers are hooked up. This way you get an effective under-counter air gap, the dishwasher does not connect to the garbage disposal, and potentially the noise is reduced.

The IPC has a specification for the minimum height between the top of the standpipe and the weir of the standpipe trap, but I don't recall exactly what it is.


 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 Appliances 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