Why does my dishwasher fill up my sink?

June 20, 2007 11:11 AM

Why does my dishwasher fill up my sink?

I've just moved to an apartment that is old but filled with new amenities. Everything works fine but when I run the dishwasher it fills up my sink with water. The only way I can empty the sink is to run the disposal. The main problem is that the sink can fill to overflowing, which means I have to monitor it while the dishwasher is working.

Granted, it's the apartment manager's responsibility to fix this, but I want to understand what is going on. Why won't my sink drain unless I run the disposal?

posted by aofl to Home & Garden (12 answers total)

It's probably your air vent/overflow. You likely have hard water and the hose is limed up. Depending on set up you may be able to clean it without taking anything apart, or you may have to unclamp the hose under your sink. Use a product like C-L-R or Lime-A-Way (or vinegar in a pinch), let it sit for an hour or so. Heavy deposits will take several applications.
posted by dhartung at 11:25 AM on June 20, 2007

There's a connection between the disposal and the dishwasher that may need to be cleaned out to prevent the back-up you describe. Running the sends the clog or excess water thru IT, then out through the drain. The dishwasher connection is located above the line where the water from the disposal drains.
Have your landlord take care of it.
posted by Carnage Asada at 11:27 AM on June 20, 2007

er... Running the disposal...
posted by Carnage Asada at 11:27 AM on June 20, 2007

Drain line is plugged up and needs to be snaked/unclogged.
posted by jerseygirl at 11:30 AM on June 20, 2007

If this is a new dishwasher it may be similar to when I put an new clothes washer in a new house. The drain was not big enough at some point to accommodate how fast the new washer drained in comparison to the old one. A big shot of Liquid Fire (sulfuric acid with a warning label that is terrifying) cleaned the gunk out of the pipe and it worked fine from then.

That being said, suggest to the landlord that the dishwasher drains faster than the pipe can handle and let him do the snaking/chemical cleansing. That is the advantage of renting.
posted by spartacusroosevelt at 11:34 AM on June 20, 2007

If you were in Minneapolis, I would recommend calling Terry the Sewer Rat - he takes care of that stuff good in my rental properties.
posted by thilmony at 11:42 AM on June 20, 2007

I had a similar problem in my new(ish) house. It turns out that I needed to get the rooter guys to root out my sewer line--just snaking the house's drain pipes wouldn't do it. One more thing to suggest to your landlord. It's also likely that if you are having this problem, others are too--ask your neighbors.
posted by adamrice at 12:02 PM on June 20, 2007

And try running the disposal first....
posted by pointilist at 12:44 PM on June 20, 2007

Besides a partially clogged drain the installer could have pointed the drain Y connection the wrong way. Look under your sink and make sure the drain hose points down stream. It should be mounted with the incoming part of the Y above the straight thru path.

Some D/Ws hook into the disposal in which case a tiny amount of water in the bottom of the sink is normal.

Also try running a couple loads without any detergent, excessive sudsing can cause a back up of water.
posted by Mitheral at 1:40 PM on June 20, 2007

Make sure the air gap is connected correctly. Then check for clogs and -- especially -- kinks in the hoses.
posted by Cool Papa Bell at 4:54 PM on June 20, 2007

I actually have had this or a similar problem, though when I ran the disposal it would sometimes also make the water dirtier. What worked when this happened was to take a toilet plunger and plunge the sink until it drained as it should. It would then drain and the dishwasher water would not fill up the sink. I figured it must have been old cooked rice or something similar clogging up the pipes.
posted by pontouf at 4:56 PM on June 20, 2007

It's a clogged drain pipe.

Just two nights ago, I had this same exact problem*, which I resolved by disconnecting the (threaded) drain pipes under the sink running a small rag secured to a fish tape because I didn't have a proper drain auger. I followed up with plunging and lots of water.

Of course, if you're renting, just compain to the landlord. Pulling a clog out of a drain is usually pretty easy, but it's a smelly, nasty job. (An open sewer drain smells like a butthole with bad breath...)

* The problem was exacerbated by the fact that the original plumber never glued on the studor vent -- he just set it in place. When the sinks filled up, the pressure was sufficient to blow off the studor vent, spraying nasty funk-water all over the place. Fun.
posted by LordSludge at 8:24 AM on June 21, 2007