dishwasher draining

**trw888** · 10-04-2010, 09:51 AM

Water backs up into our kitchen sink every time the dishwasher goes into its drain cycle. It's not a lot of water; it barely covers the bottom of the sink. The water doesn't back up until near the drain cycle and as soon as the drain cycle ends the water quickly does down the drain. It's done this for a couple of years. It hasn't gotten worse; it hasn't gotten better over that time. The p-trap isn't clogged. I did about two weeks of Bio-clean, but that had no effect.

Is there anything I could and/or should do about this?

Thanks.

**Terry** · 10-04-2010, 11:16 AM

It could be a plugged p-trap below the sink, it could be a clogged line in the wall.
The first step is removing the p-trap and making sure it's empty.

**trw888** · 10-04-2010, 11:43 AM

Thanks Terry. I've already checked the p-trap and it's clear.

I know it's probably a clogged line, but the sink drains fine otherwise. It's just when the dishwasher is draining that there's an issue -- like the drain can't handle the amount of water coming out of the dishwasher. I've put off dealing with this because we've spent a fortune on other plumbing issues recently (house was built in 1952). I guess what I want to know is how big a deal is this? And is it possible that all it needs is a plumber to snake out the line?

**Redwood** · 10-04-2010, 12:17 PM

Originally Posted by trw888

Is it possible that all it needs is a plumber to snake out the line?

That would be my guess.

**trw888** · 10-04-2010, 12:51 PM

Thanks Redwood. I know this is probably a dumb or obvious question...But is this something I should deal with soon? I've been told that it's a health concern??? I know it probably wouldn't cost more than $100, but money is an issue right now.

**Terry** · 10-04-2010, 01:09 PM

A slow drain is a health hazard?
Maybe an inconvenience. I don't think water coming from a dishwasher is much different then when you hand wash your dishes.
If it's plumbed with an Air-Gap, the water can't siphon back into the dishwasher.

**trw888** · 10-04-2010, 02:00 PM

Yeah, I didn't understand it either. But I thought I would ask just in case there was something to it. Thanks again.

**nukeman** · 10-04-2010, 03:02 PM

Besides having a clog, couldn't this also be caused by a poor install? I don't know what kind of setup the OP has, but I could see that if the DW had a simple tee connection into the tailpiece (not directed, no baffle), then some of the water may go up while the rest goes down. Since it drains okay normally, maybe it is an install issue?

Any pics of the install?

Based on the age of the house, you might have galvanized pipes and that could also add to the draining issues (buildup of rust, etc.)

**Inspektor Ludwig** · 10-04-2010, 05:51 PM

My guess is since the house was built in 1952 Nuke was right when he said it probably has galvinized pipes or maybe even some old crusty cast iron. My guess is also that the vertical drain is 1-1/2 and not a typical 2" that you see today. Back then the only dishwashers were the kids. Combine crusty pipes, 60+ years of food and who knows what else and you're sure to have a slow drain. You're right when you say it won't get any better, even the best installed galvinized or cast iron piping has a shelf life and 60+ years is pretty good. Not to scare you but at some point you're going to need to consider replacing some waste piping. Snaking old piping may bring more problems. If having some water in the sink doesn't bother you then I would just leave it alone for now.

hj · 10-04-2010, 06:05 PM

The only possible health hazard would be if the dishwasher "siphoned" some of the backed up water from the sink back into the dishwasher and then sprayed it on the dishes again. There is a cure, and usually it is a simple one. I had one customer who had three plumbers check their drain, which was doing the same as yours, and finally, when they had had enough of it, they called me and it took about 30 minutes to cure the problem.

**trw888** · 10-04-2010, 08:37 PM

Thanks everyone. I thought it may have been an install issue as well, but I had an appliance repair person take a look at it when he was out for another repair and he said it was fine. The install looks exactly like Terry's diagram. I think at this point I'm going to leave well enough alone. I have no illusions that the pipe will need to be replaced at some point. We've already replaced plenty of other piping. I don't want to do anything that could lead to more failures. And the water really doesn't bother us.