How screwed am I?

[jseyfert3]

There's several different scenarios, depending on how your dishwasher (DW) drain returns to the sink's drainage system (and how many sinks you have). There are three ways (at least?) to plumb the DW drain. One is like yours, directly into the drain system. The second goes first into a garbage disposer (GD), which leads into the drain system. Of the two, into the GD is preferred, only because the GD can chew up any large chunks of food before introducing that waste into the sewer system. But neither of those routes is affected by how many dishes are in the sink, or if the sink is stopped up.

The third route is through an air gap fitting over your sink. That MO is a two-fer. The DW waste routes through that fitting such that if the drain system ever got backed up, the DW waste water would empty into the sink, rather than back-flowing back into the DW. The best way to plumb the air gap is to have the gap over one sink, and the exit hose from the air gap plumbed to the drain (or GD) of the other sink. So say the GD gets clogged up, then the DW waste would back up but exit through the air gap (instead of back flowing to the DW) and drain into the other sink. If that sink's drain is free, then the DW waste goes through to the sewer. But if both sinks are backed up, then the DW waste will collect in the sink, hopefully not overflowing it before noticed. So a correctly routed air-gap setup is the safest, because there are several places the DW waste can end up before it gets back to the DW or onto your floor. Whew, OK...

One way dishes in the sink matter is if the air gap gets used, and the DW waste gets trapped in the sink due to dirty dishes or a closed strainer or otherwise blocked sink drain.

As mentioned, you're supposed to run the GD right before you run the DW, clear the path between the air gap and sink, and be sure all the drains are open and ideally no dishes in the sink. But that's if you have an air gap. You don't, and your DW drain doesn't run to a GD, so none of the above applies to you.

But if you were inspired, you could redo that. Your "worst case" is DW food waste routed directly to the drain pipe, which could get backed up, and then you'll have a real mess. It might backflow into the sink, if that sinks drain is clear, or it might backflow to the DW. This is the other reason a sink full of dishes blocking the drain matters: but only if the drain pipe is clogged. I don't know that the loop under the counter is going to matter much in that scenario.

The loop under the counter is really only for keeping the sink water from getting to the DW, which it does, unless the level of water in the sink is higher than the loop. Which is why an air gap over the sink is better for that, too, because the air gap is never going to be lower than the water in the sink.

So... the best way to plumb the DW drain line:
DW --> air gap --> GD, with the air gap fitting over the non-GD sink if you have two sinks.

If you don't have a GD, then it's:
DW --> air gap --> drain pipe of sink #2, with the air gap fitting over sink #1, if you have two sinks.

This was rather long, and didn't answer my original question of how a plate plugging a sink would cause the dishwasher to fill up with water from the sink.

However, I agree in general with what you've written, except two comments:

• I don't think plumbing to the garbage disposal is needed. Dishwashers either have built-in disposals (very rare these days) or they filter the water, so I don't see how large food particles are going to clog up the drain.
• I doubt the sink 1 vs sink 2 thing matters. There's only one drain pipe, and all double sinks I've seen have a divider between sinks lower than the top of the sink, so if one sink it plugged it overflows into the second sink before the sink overflows onto the counter/floor.

In any case I agree an above sink air-gap is the way to do it, which is why a lot of codes require that now. And yes, despite @Rattus Suffocatus's opinions about them, I'm going to put one in. Why do you hate it so much anyway @Rattus Suffocatus?

 

[Dirk]

That sounds reasonable. Though what I think I just read was: if you pour some of your beer all over everything, then you're good!

It really does come down to your own best judgement...

Of course, I would recommend you try to make said judgements without first dosing yourself with any of that same beer!

 

[newdude]

Of course, I would recommend you try to make said judgements without first dosing yourself with any of that same beer!

*thinkin juice.

 

[Rattus Suffocatus]

You are overthinking this officially now. And that is saying a LOT from me, the original overthinker!

I don't like them because I think they are ugly, noisy, and only slightly improve the situation and really don't do much to protect anything... And need an extra hole in the granite.... (Yes, you can probably get around this with a different faucet.) You can put one of those under the sink right at the top of the sink and not get 100% protection but 98% if you desire. You'd only drain to that level.

I've had my dishwasher here back up more than once. It has a sensor in it and shuts it down when that happens.... so it's at best a secondary protection device. Keep the dishwasher in good working order and you should be okay. And especially here, we are on a slab.

Your Disposer: The 100% solution really is running it right before running the dishwasher EVERY time you go to start a load.... Whether or not you have the dishwasher drain run through it or around it. That will pretty much fix that problem before it happens.

Oh.. you think you don't want to have that feature.. okay.. make sure you pick a model that absolutely has a chopper than (i.e. not a Bosch). If the two sink drains are attached under a disposer, the real problem (especially when you have teenagers) is that the disposer can back up... so even though you are supposed to run it there, I am not sure if it would be better to bypass it due to the fact that has happened to me here about 5 times now... It's not a huge deal when it does, but it's annoying to wake up the next day to dirty dishes and a mess in the bottom of the dishwasher... Now to clean that up all you need to do is run the Disposer, make sure it's no longer backed up, start a cycle on the dishwasher. Let it run a minute or two and cancel. Do that again. At that point it should be clean and you can wash your normal dishes.

Leaving that thing out is pretty low risk if the plumbing underneath is correct.

 

[Dirk]

Leaving that thing out is pretty low risk if the plumbing underneath is correct.

Agree. But not about installing the air gap fixture under the sink, if that's what you meant. If you don't want to install an air gap through the sink or granite, then don't use it at all and create a hump in the DW drain line that gets as close to the underside of the counter as possible.

 

[JJ_Tex]

You probably want to see what your local jurisdiction requires for code. Here we either need to have an air gap or a "high loop" which is what Dirk is describing above. If a home inspector is going to ding you for it down the road when you sell, you might as well add it now.

 

[jseyfert3]

You are overthinking this officially now. And that is saying a LOT from me, the original overthinker!

Overthinking the mold or the dishwasher? I wasn't overthinking that, that was @Dirk! I was just curious what setup @Sollace had that their dishwasher was backfilling, cause that points to improper drainline routing (air gap or no).

Mostly this debate about the dishwasher plumbing is just fun.

And need an extra hole in the granite.... (Yes, you can probably get around this with a different faucet.)

I don't think so in my case. I don't have an undermount sink. If I recall correctly when planning to install an RO drinking water faucet, my granite is cut back the entire "back strip" of the sink where the faucet mounts. So all I need to do is drill a hole in the iron sink ledge, and not the granite.

For undermount sinks, yet, you'd have to drill through granite if it didn't come with a hole.

Your Disposer: The 100% solution really is running it right before running the dishwasher EVERY time you go to start a load.... Whether or not you have the dishwasher drain run through it or around it. That will pretty much fix that problem before it happens.

Oh.. you think you don't want to have that feature.. okay.. make sure you pick a model that absolutely has a chopper than (i.e. not a Bosch). If the two sink drains are attached under a disposer, the real problem (especially when you have teenagers) is that the disposer can back up... so even though you are supposed to run it there, I am not sure if it would be better to bypass it due to the fact that has happened to me here about 5 times now... It's not a huge deal when it does, but it's annoying to wake up the next day to dirty dishes and a mess in the bottom of the dishwasher... Now to clean that up all you need to do is run the Disposer, make sure it's no longer backed up, start a cycle on the dishwasher. Let it run a minute or two and cancel. Do that again. At that point it should be clean and you can wash your normal dishes.

Leaving that thing out is pretty low risk if the plumbing underneath is correct.

Or...don't run the drain line to the garbage disposal. That's how our dishwasher was run in our house we've had for a year. We do have a garbage disposal but the dishwasher is just plumbed into the tailpipe on the non-garbage disposal pipe. And I think our current dishwasher (the one that leaked and will be replaced) did not have a chopper, just a filter. Guess what? This setup worked great! No sink backups. No dishwasher backfilling from the sink. We've been here a year now, and run the dishwasher on average once a day, even though it's just the two of us, as we do a lot of cooking and don't order/go out very often.

Also I disagree you are supposed to run a dishwasher to the garbage disposal. I did a quick Google search and all I could find was that running to a garbage disposal was either because:

• It is convenient, as if you had a disposal these universally have connections for dishwashers, so you can then could connect to that rather than swapping your sink tailpiece to one with a dishwasher connection, or
• The disposal may be considered an air gap depending on local code, which may allow skipping the install of an over the sink air gap, depending strongly on local code.

That's it. I couldn't find any reference to plumbing a dishwasher to a garbage disposal for the purposes of grinding up any waste from the dishwasher. And really reading here it sounds like plumbing to the garbage disposal causes issues, and has made me determined NOT to plumb it to the garbage disposal when I install the new dishwasher!

Agree. But not about installing the air gap fixture under the sink, if that's what you meant. If you don't want to install an air gap through the sink or granite, then don't use it at all and create a hump in the DW drain line that gets as close to the underside of the counter as possible.

You probably want to see what your local jurisdiction requires for code. Here we either need to have an air gap or a "high loop" which is what Dirk is describing above. If a home inspector is going to ding you for it down the road when you sell, you might as well add it now.

Yes, agreed with both of you. I will definitely want to do what code requires, and plan on putting in an air gap even if not required, unless it would be banned (not sure why it would be). The one thing I will NOT do is put an air gap under the sink! No way I'm doing anything that increases the possibility of leaking water out of sight!

 

[Sollace]

Wait, how does a plate plugging the sink drain cause the dishwasher to fill up with water from the sink?

And if draining a sink of water backflows into your dishwasher, that means your hose is routed wrong.

Yes. We suspect our dishwasher is rerouted wrong. Two days in a row our dishwasher flowed out from the floorboards into the kitchen. At first I thought it was the fridge. We ran the dishwasher again. What we found is the water sitting in the sink was flowing into the dishwasher. Our 'fix' involves using the garbage disposal and flushing the sink regularly.

Yeah, I'm not technical but maybe that makes sense to someone.

 

[Dirk]

What we found is the water sitting in the sink was flowing into the dishwasher.

Depends on if the DW is running at the time. You either need an air gap or to make sure the DW drain line is "humped" as high as it can go, it might have slipped down. Or it might be a clog in the DW drain line.

 

[Dirk]

I couldn't find any reference to plumbing a dishwasher to a garbage disposal for the purposes of grinding up any waste from the dishwasher. And

This was more true before DWs had grinders. I still maintain it's better to run DW waste through the GD, to catch things before they can clog a drain, but it really doesn't matter all that much. The DW drain fitting on the GD is handy for single sinks.

What is more important is that the air gap is above the opposite sink that the DW drain line connects to, whether that is the GD or the tail pipe.

 

[Dirk]

Mostly this debate about the dishwasher plumbing is just fun.

Or the most interesting thing going on! Is it so slow at TFP in January that this thread stretched to 111 posts!!??!!

 

[Sollace]

No one is swimming! Everyone is home more and sitting on their computer/lap top/phone!
I've noticed I've been on You Tube more, catching up on the news. Anything to get my mind off the pool build. !!!

 

[jseyfert3]

Or the most interesting thing going on! Is it so slow at TFP in January that this thread stretched to 111 posts!!??!!

Omg that many already!? Wow. Also I think @Leebo may be starting to regret opening up unlimited TFP picture hosting soon...

Oh yeah, and I just fixed a design flaw in our Samsung fridge that causes the drain line to freeze up and water to collect in the bottom of the fridge. Now the freezer is wonky, not making ice and not getting down to the 0 °F I selected (it’s only getting down to like 14). The fun of homeownership!

 

[Katodude]

So I dont know about codes, but we replaced our countertops this year and the wife did not want a hole cut for the air gap switch for the disposal. Those switches are also ugly. So a little research and I found one of these.

didikit Garbage Disposal Wireless Switch Kit, Remote Control Outlet with Timer Switch, Sink Top Waste Disposal On/Off Switch Button for Insinkerator, Waste King Waste Food Disposer, 16A/1800W, Black - - Amazon.com

didikit Garbage Disposal Wireless Switch Kit, Remote Control Outlet with Timer Switch, Sink Top Waste Disposal On/Off Switch Button for Insinkerator, Waste King Waste Food Disposer, 16A/1800W, Black - - Amazon.com

www.amazon.com

Its also nice that you can push a button and it turns off automatically in 30 seconds.

I liked the idea so much, I went a step further. I installed an Insteon switch for the disposal, and have a remote button that is programmed with a bunch of settings. On, off, on for 10 sec, on for 15 sec, on for 30 secs.

I wont mention that I can also have Alexa turn on the disposal for an automated 15 seconds (nice when hands are dirty). Its just me and the wife with no children so we feel it is safe enough for us.

 

[Sollace]

Well. .. . If you're really bored and need a handy fixer project to do. .. .
Hubby wired our exhaust fan in the bathroom(s) on a timer. So you can program the fan to be on for 10 minutes, 20, or 30 and it automatically turns off. We've had them for years, no more leaving the fan running forever and forgetting to turn it off.

 

[Rattus Suffocatus]

Yeah it only backs up if we run the dishwasher with the drain plugged which makes sense. It doesn't fill up the dishwasher if it's just plugged up on it's own... Like I said, the dishwasher just shuts off at that point which is a little more than just annoying, I've not ever had any leak out. It does pull in crud from the plug though which is why it has to be rinsed out when that happens.

Like I also said, I just tell everyone in the house to make sure that the left sink is empty, all of the forks and knives are out of the disposer, and then to run it for about 10 seconds... it's not a major problem.

 

[superuser]

Y'all do scrape and rinse your plates a bit before tossing 'em in the dishwasher, right? The drain hose on the dishwasher is like 1/2" ID, not much of the chunky leftovers is really coming out of there. Your washer has screens in the bottom to catch most of the solids too.

Personally, if a high loop meets code in WI, I would do the loop. It's a lot quieter than the gurgling of the air gap and achieves nearly the same result. Whether you drain into a disposal is mostly immaterial, again since the size of the chunks coming out of your dishwasher drain are not exactly large. If you do allow your disposal to back up, it's more likely from things you put down the sink than in the dishwasher. With a high loop you'd still have to fill the sink basin to a level higher than the loop to drain back to the washer.

On the mold aspect, what you've accomplished looks better than several of the professional remediation jobs I've seen in the Houston area that passed inspection. Generally you wouldn't worry about what wicked into the subfloor if it is stable, and hasn't warped or buckled.

 

[jseyfert3]

Y'all do scrape and rinse your plates a bit before tossing 'em in the dishwasher, right?

Nope. I scrape any large food bits into the trash, but I never rinse. If it's just sauce or whatever straight in it goes. I just had this discussion with coworkers. I've seen people rinse their dishes to the point they look clean, sometimes with scrubbing, if they had done that with soap they'd be done and could put the dishes in the drying rack and skip the dishwasher completely. My view is the dishwasher needs to be able to wash the dishes, straight from the table (again scraping for any large amounts of leftover food). Otherwise I may as well wash them by hand.

So I told this to a coworker who always rinsed his dishes after he saw me put an unrinsed plate into the work dishwasher. He had just moved into a house, lived in an apartment prior, with the typical dirt cheap apartment dishwasher, hard water, and the modern phosphate free detergents. This is a recipe for disaster and doesn't work. However he now lived in a house, with a water softener, and a high end dishwasher, but was still pre-rinsing. I told him he should try skipping the pre-rinse. He did...and grudgingly admitted I was right and the pre-rinse wasn't needed, and is now extremely happy that he doesn't have to pre-rinse dishes.

In any case dishwashers have either built-in disposals or filters, so they aren't sending large chunks of food down the drain, pre-rinse/scraping or no.

On the mold aspect, what you've accomplished looks better than several of the professional remediation jobs I've seen in the Houston area that passed inspection. Generally you wouldn't worry about what wicked into the subfloor if it is stable, and hasn't warped or buckled.

Thanks. There certainly is not a moldy/musty smell anymore, after the cleaning, which is one of the points in the EPA guide on cleaning up mold for saying mold remediation is complete. To be clear, it did smell moldy before the cleaning.

I've been tired and doing other things, so further cleaning has been in a holding pattern since I got the exposed mold cleaned up. I think I'll try to dig into the cabinet to the right of the dishwasher tonight, get that side taken care of. Then over the next few days start digging up the dining room floor to inspect the subfloor that has bulged up over there.

 

[superuser]

Nope. I scrape any large food bits into the trash, but I never rinse. If it's just sauce or whatever straight in it goes. I just had this discussion with coworkers. I've seen people rinse their dishes to the point they look clean, sometimes with scrubbing, if they had done that with soap they'd be done and could put the dishes in the drying rack and skip the dishwasher completely. My view is the dishwasher needs to be able to wash the dishes, straight from the table (again scraping for any large amounts of leftover food). Otherwise I may as well wash them by hand.

So I told this to a coworker who always rinsed his dishes after he saw me put an unrinsed plate into the work dishwasher. He had just moved into a house, lived in an apartment prior, with the typical dirt cheap apartment dishwasher, hard water, and the modern phosphate free detergents. This is a recipe for disaster and doesn't work. However he now lived in a house, with a water softener, and a high end dishwasher, but was still pre-rinsing. I told him he should try skipping the pre-rinse. He did...and grudgingly admitted I was right and the pre-rinse wasn't needed, and is now extremely happy that he doesn't have to pre-rinse dishes.

In any case dishwashers have either built-in disposals or filters, so they aren't sending large chunks of food down the drain, pre-rinse/scraping or no.

I'm in the camp of I'd rather rinse the dishes than frequently empty dishwasher filters, so if it's something that isn't reliably soluble in water it's going in the can or disposal. I will admit the new Kitchen Aid we put in works incredibly well though, better than the "washed fine but wouldn't dry plastic" GE it replaced, or the silly expensive Bosch we put in the previous house. Pro tip, don't buy a Bosch (washed fine, wouldn't dry anything).

 

[Rattus Suffocatus]

Heh.. wait until you have teenagers. That is why I've had it back up a few times... they pile the stuff up in the sink without rinsing at all (and in Arizona, you don't do that*) and it often will plug up the disposer. Then if you run the dishwasher with the clogged sink it will backup. The dishwasher detects that and stops. It isn't the end of the world like I said before.

In Wisconsin (like me in Iowa previously and growing up in Illinois) you have to worry about mold if you don't rinse dishes off and let them sit for 2-3 days... Even the mold will wash off in a dishwasher. *In Arizona, if you do that the food dries on to the plate and then doesn't come off during even an extended cycle (it usually doesn't mold). So I try to have the kids rinse. They don't and I have to use the stainless steel scrub pad a lot on the glassware... On other stuff it sometimes takes three days of soaking to then remove reasonably...

(*The dried on stuff literally turns into something resembling adobe or concrete here...)

So the compromise is to just run them under water for a couple of seconds when putting them in the sink... that makes a world of difference... unless you are going to run the machine within a few hours. Things like cheese stuck to a plate I do ask them to scrub off...

And by the way, don't feel bad. I had a kid in the hospital (boy, was that expensive because it was over two years copay) and my mom in Chicago is still in the hospital.. it's been a bad 6 weeks... I gray watered my hot tub too when it went about 3 days at 0 FC. I have it running strong bleach and Ahhsome for a couple of days... it was past due for a water change anyway. The water looks great now if a little foamy! So all is not completely dull in TFP land... But I have a water change to sneak in sometime after work this week....