Sink Stink

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delabeaux
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Sink Stink

Post by delabeaux » Sun Jun 25, 2017 1:04 pm

I have a relatively new house, 2015. Last year, a similar smell happened, stinky under the sink. I changed the air-admittance valve, and it seems to have resolved. It's back. I plan to change this and the dishwasher drain hose but I'd like anyone to review how they set up the drain hose... it's draining into an open pipe (pictured on the left). It has a random Y pipe near the top. It does have a water trap at the bottom before going on but should the dishwasher drainage be like this?
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delabeaux
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Re: Sink Stink

Post by delabeaux » Sun Jun 25, 2017 1:05 pm

Unsure why the pose turned this 90 to the left...

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A. Spruce
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Re: Sink Stink

Post by A. Spruce » Sun Jun 25, 2017 1:18 pm

Can you get a better picture of the Y and dishwasher connection behind the sink? Also, the dishwasher discharge hose looks to have mold inside it.
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delabeaux
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Re: Sink Stink

Post by delabeaux » Sun Jun 25, 2017 1:57 pm

Sure
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A. Spruce
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Re: Sink Stink

Post by A. Spruce » Sun Jun 25, 2017 2:16 pm

Well, I have to say, I've never seen a dishwasher hooked up that way, and I can't imagine that it passes code.

Used to be, dishwashers were hooked to an air gap that fed into the bottom of garbage disposal. For some reason this method became frowned upon, so the air gap was hooked into the side of the sink drain neck. This system prevents dirty water from being pulled into the dishwasher, while still maintaining a sealed drain system.

The way your system is plumbed, it is ripe for all kinds of problems. If you don't use the dishwasher every other day or two, especially in hot weather, the water trap can dry out, allowing sewer gases to escape. If the drain line ever becomes clogged and you aren't aware of it, the dishwasher will empty under the sink, causing cabinet damage and much worse.

If it were me, I'd plumb an air gap above the sink and tee the dishwasher discharge line into either the disposal or into a T-neck into the sink drain. and cap off the current dishwasher drain above the trap, as this will be the easiest way to delete that section.

As I mentioned earlier, it looks like there is mold in the dishwasher discharge hose, if so, start adding 1 cup of white vinegar to the last rinse cycle of every load. This will help not only keep crusty build up out of the dishwasher, it will kill the mold in the discharge line.
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delabeaux
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Re: Sink Stink

Post by delabeaux » Sun Jun 25, 2017 3:54 pm

Interesting. We live in Loveland Co, and this was a new build inspected on build completion and again before buying. We run the dish washer daily, sometimes 2-3 times a day (family of six).
Thoughts: I may re-replace the air admittance valve and the washer disposal line. An above the sink air-gap may be more difficult as we have a granite countertop.

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Shannon
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Re: Sink Stink

Post by Shannon » Sun Jun 25, 2017 4:02 pm

Yes that for sure is causing you some issues. I do not know what they were thinking leaving things open like that!
I have a video that will help explain what Spruce was saying about moving the drain hook up. https://www.youtube.com/watch?v=22PU1-98b6E
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Re: Sink Stink

Post by Shannon » Sun Jun 25, 2017 4:03 pm

I'm actually surprised to see the AAV under the sink as well? Is this sink in an island maybe??
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Aaron
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Re: Sink Stink

Post by Aaron » Sun Jun 25, 2017 4:04 pm

Yeah I don't know why a 2015-built house has an AAV under the sink? Should have a vent to the roof.

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Shannon
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Re: Sink Stink

Post by Shannon » Sun Jun 25, 2017 4:05 pm

delabeaux wrote:Interesting. We live in Loveland Co, and this was a new build inspected on build completion and again before buying. We run the dish washer daily, sometimes 2-3 times a day (family of six).
Thoughts: I may re-replace the air admittance valve and the washer disposal line. An above the sink air-gap may be more difficult as we have a granite countertop.
I would not worry about getting the air gap above the counter, around here no one does that either. Make sure when you route your DW drain hose that it at some point rises as high as it can inside the cabinet before being hooked to the drain.
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A. Spruce
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Re: Sink Stink

Post by A. Spruce » Sun Jun 25, 2017 5:24 pm

The AAV under the sink has me a bit baffled as well, unless as you said, this is an island, but the drywall seen through the cabinet indicates this is against a wall.
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delabeaux
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Re: Sink Stink

Post by delabeaux » Sun Jun 25, 2017 6:14 pm

Thanks all, yes, it is an island with some drywall on the front side. Interestingly, most of the house sinks, bathrooms, have the AA valves, and they are wall-sinks. I'll let ya'll know how it goes after viewing the vid :).

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Re: Sink Stink

Post by delabeaux » Sun Jun 25, 2017 7:22 pm

For the current pipe that the drain is going into, it's a 1 1/2" pipe. I'm thinking I'll cut this, cap and seal, then add a wye connection from the sink after routing the dishwasher drain pipe as described previously by Shannon. Will capping the current drain pipe cause any issues?

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Aaron
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Re: Sink Stink

Post by Aaron » Sun Jun 25, 2017 7:24 pm

I think the reason you're getting foul odor is because you don't have a sealed drain, and likely because the dishwasher is discharging at a point higher than the AAV. Also what is the deal with that CPVC piece (the "U" shape) that your dishwasher's discharge hose is clamped to? And the wye fitting on the standpipe for no apparent purpose?

Whoever worked on this didn't know what they were doing and either your inspectors didn't look under the sink, or they didn't know better themselves.

You need either a garbage disposer with a dishwasher port, or you need a sink drain tailpipe with a barbed connector to clamp the discharge hose to. This connection must be made before the P-trap. The hose also needs to make a "high loop" from the dishwasher to the drain connection. Some states require an air gap device.

I follow a local inspection blog, and they are *constantly* posting pictures of under-sink plumbing horrors, so unfortunately it's not an uncommon thing in many homes to see "creative solutions" under sinks.
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A. Spruce
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Re: Sink Stink

Post by A. Spruce » Sun Jun 25, 2017 8:18 pm

My suspicion is that the final inspection didn't include looking at the under sink plumbing, otherwise this would most likely have been shot down in a hurry. I also suspect that builders these days are trying to cut corners and costs more than ever, hence AAV's at all locations rather than running actual vent lines through the roof. Granted, this is an island, so AAV makes sense, but the OP mentioned that all the other fixtures in the house are plumbed similarly.

Who knows what the installer was thinking with that set up, but it is most certainly the source of the odor.

I do recall now why the port on the disposal was abandoned by code, it is because the disposal can plug the port, causing dirty water to remain in the dishwasher, thus creating a bio hazard. This is why the dishwasher connection was moved to the sink drain neck instead.
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Re: Sink Stink

Post by delabeaux » Sun Jun 25, 2017 10:23 pm

True... Northern Colorado right now is CRAZY for building (home prices are going through the roof)... we've had ~70 homes go up in our neighborhood alone, THIS SUMMER. Builders are in a frenzy, so likely inspectors are too...

I'll be working on this tomorrow and will post the results, here's my plan:

1.) cut 2" pipe abive sink p trap connection to main drain pipe,high as possible.

2.) add 2" coupler

3.) add 2" pvc pipe ~6+" to raise the height of the studor vent

4.) add 2 --> 1 1/2" converter bushing

5.) add studor vent

6.) cut and cap current dishwasher 2" pipe.

7.) add a 1 1/2" wye dishwasher connection to the sink drain, above the p-trap.

8.) install new dishwasher drain hose.

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Re: Sink Stink

Post by Shannon » Mon Jun 26, 2017 6:57 am

delabeaux wrote:I'll be working on this tomorrow and will post the results, here's my plan: 1.) cut 2" pipe abive sink p trap connection to main drain pipe,high as possible...
That all sounds good to me.
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Re: Sink Stink

Post by delabeaux » Wed Jun 28, 2017 7:46 am

Ok, here's what I've done. Rather than just cap the previous dishwasher drain line, I cut out the complete drain setup. Extended the current studor vent quite a bit higher, added the dishwasher drain pipe to the sink drain pipe. For now, I'm opting to try the vinegar in the dishwasher to save additional time in replacing the current dishwasher drain hose but I have it on hand to replace if needed.
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A. Spruce
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Re: Sink Stink

Post by A. Spruce » Wed Jun 28, 2017 8:09 am

That looks SOOOOOOO much better! 8-) Let us know how the modifications work out. 8-)

Now that the DW drain line is more visible, that looks like purple staining on the outside of the pipe, indicating that it is PVC primer that was dripped onto the pipe when the under sink connections were made by the original installer. If this is true, then you may not have a mold/mildew issue in the dishwasher or drain line. Still, using vinegar in the rinse will not only result in cleaner rinsing, it clean out and will minimize sludging within the DW internal plumbing, a problem that I've had with the DW I installed a couple years ago. Another side note is that I had to switch to liquid DW detergent because the new machine won't dissolve the crystals, and, I use a fraction of what the label recommends, otherwise there is a soap film left on everything.

At any rate, congrats on a job well done, we look forward to hearing updates from you. 8-)
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Aaron
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Re: Sink Stink

Post by Aaron » Wed Jun 28, 2017 9:00 pm

Bravo!!! :D

By the way, you can take a blade or scissors and cut off the wide diameter part of the rubber dishwasher hose connection to the barbed tailpipe nipple, then just use one clamp.

The wide diameter end is to connect to a disposer, but it's getting in the way of the narrow connection you're making to the tailpipe. (I have NO IDEA why there are two diameters!)

Looks much more normal. I don't think you should have any issues now!

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Shannon
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Re: Sink Stink

Post by Shannon » Wed Jun 28, 2017 9:23 pm

yup great job, that is the way things should have been from the beginning!
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Re: Sink Stink

Post by Mastercarpentry » Sun Jul 02, 2017 6:26 am

Aaron wrote:I think the reason you're getting foul odor is because you don't have a sealed drain, and likely because the dishwasher is discharging at a point higher than the AAV. Also what is the deal with that CPVC piece (the "U" shape) that your dishwasher's discharge hose is clamped to? And the wye fitting on the standpipe for no apparent purpose?

Whoever worked on this didn't know what they were doing and either your inspectors didn't look under the sink, or they didn't know better themselves.

You need either a garbage disposer with a dishwasher port, or you need a sink drain tailpipe with a barbed connector to clamp the discharge hose to. This connection must be made before the P-trap. The hose also needs to make a "high loop" from the dishwasher to the drain connection. Some states require an air gap device.

I follow a local inspection blog, and they are *constantly* posting pictures of under-sink plumbing horrors, so unfortunately it's not an uncommon thing in many homes to see "creative solutions" under sinks.
You've hit the bullseye :D Dunno about the codes there, but good plumbing practice and code here is that you may not use an AAV except where normal venting is impossible, and then it must be mounted as high as is possible while remaining accessible for servicing, and at the very least above the level of the highest drain it serves. If it is below any drain, floating debris and soap can get to the valve adversely affecting it's operation. Yeah, we've all seen them work when done otherwise but when there's a better way you should use it. Were this mine I'd rip it all out and do it right, but I'm pretty picky about drain plumbing because I hate dealing with drain problems :(

Phil

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Aaron
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Re: Sink Stink

Post by Aaron » Mon Jul 03, 2017 10:37 am

By installing the AAV "above the level of the highest drain it serves", what you mean is the drain's trap, right? Or do you mean the actual hole in the sink where a drain begins?

Because it could get pretty tough to get the AAV higher than the bottom of a sink basin with space limitations within a sink base vanity.

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Re: Sink Stink

Post by A. Spruce » Mon Jul 03, 2017 12:56 pm

Aaron wrote:By installing the AAV "above the level of the highest drain it serves", what you mean is the drain's trap, right? Or do you mean the actual hole in the sink where a drain begins?

Because it could get pretty tough to get the AAV higher than the bottom of a sink basin with space limitations within a sink base vanity.
I would say the bottom of the sink, as this is where backup will be should the line get clogged. It is debris within this waste water that plugs up the AAV, the higher the AAV, the less inclined it is to get debris in it. 8-)
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Re: Sink Stink

Post by Shannon » Mon Jul 03, 2017 4:33 pm

Aaron wrote:By installing the AAV "above the level of the highest drain it serves", what you mean is the drain's trap, right? Or do you mean the actual hole in the sink where a drain begins?

Because it could get pretty tough to get the AAV higher than the bottom of a sink basin with space limitations within a sink base vanity.
Above the lowest drain,so in this case you want it as far above the bottom of the sink as possible..
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Re: Sink Stink

Post by Aaron » Tue Jul 04, 2017 2:37 am

Yeah good luck with that in a small bathroom vanity. This is why these things should be avoided in the first place.

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Re: Sink Stink

Post by Angie H. » Wed Aug 09, 2017 2:52 pm

I have been dealing with the same thing - a bad odor coming from under the sink & after reading this & taking a look at the pipes, I noticed that my dishwasher is draining into an open pipe also. When I lightly pulled on the dishwasher drain hose, it came up out of the pipe easily, so I don't think it's fastened to anything & I could hear water sloshing - it feels like the hose is resting in water. However, it looks like I have 2 drains - 1 for the dishwasher & 1 for the sink (which has 2 sides, so 2 drains coming out of the sink going into 1 of the drains in the wall). I know nothing about plumbing, so this question may seem stupid, but would there be a piece to add to the top of the open pipe that the dishwasher hose could attach to but would be closed at the top? So basically like what the original poster added to his, but capped off to use at the top. Here are some pictures. Thanks!
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Re: Sink Stink

Post by Angie H. » Wed Aug 09, 2017 2:54 pm

That hose that looks like it goes to the top of the picture is going to the separate sprayer that is next to the faucet in the sink.

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A. Spruce
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Re: Sink Stink

Post by A. Spruce » Wed Aug 09, 2017 3:44 pm

Angie H. wrote:
Wed Aug 09, 2017 2:52 pm
I have been dealing with the same thing
The repair would be the same as above. You need an air gap installed on the dishwasher discharge line and at the very least an AAV on the drain with a proper dishwasher nipple.

You can either drill and tap a nipple into the existing drain, or install a drop tube in the sink drain that has a nipple on it, or connect to the nipple on the disposal. If you go with the last one, there is a plug inside the disposal that you have to knock out before you attach to it.
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Re: Sink Stink

Post by Angie H. » Wed Aug 09, 2017 8:39 pm

Ok, I'm a little confused. Do you need to have an air gap if the dishwasher drainage hose makes a "high loop"? Also, is an AAV necessary if your plumbing is vented to the roof (which mine is)? My garbage disposal does have a place to attach the dishwasher drainage hose, but there was something earlier in this discussion that said it shouldn't be used since food from the disposal could clog the dishwasher drain line. Also, I'm not sure what a drop tube is. I was hoping I could just add a wye connection to the top of that open pipe that the dishwasher drain is currently draining into, connecting the dishwasher drain there (since it would still be making a "high loop") & capping off the other end. Or will this cause problems?? If I added the wye connector to one of the sink drains (either after the disposal but before the p trap on the one side or else on the other side) would I just cap off that standing open pipe, & if so, would that cause problems?

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