Thread Number: 89194  /  Tag: Modern Dishwashers
Dishwasher Draining - Pros/Cons of direct vs via disposal?
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Post# 1137756   12/29/2021 at 12:36 by LowEfficiency (Iowa)        

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Hey folks, quick question-
For a modern dishwasher in a new installation, is there any particular reason why draining via the port in a disposal is preferable?

Typical benefits listed are that food waste gets an additional grinding, and that plumbing/installation is simpler because the disposal has the port on the side.

But it seems like that second grinding should be a non-issue, as a modern dishwasher either includes a grinder itself, or has a user-cleanable filter system to catch larger food items. The dishwasher discharge pipe is far smaller than the sink drain pipe it feeds into, and corrugated to boot, so I'm not understanding how this secondary grinding helps (or is necessary)?

On the flip side, feeding into the disposal means that the user must remember to run their disposal manually, at least periodically after doing dishes, as food scraps from the dishwasher will be deposited into the disposal... Whereas if the dishwasher discharged into the drain line directly (minding the proper trap/venting configuration, etc), this wouldn't be necessary.

Am I missing something, or is plumbing convenience the only real benefit?

Post# 1137759 , Reply# 1   12/29/2021 at 13:01 by ea56 (Cotati, Calif.)        

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I donít know that there are any advantages to draining the DW via the garbage disposal vs the sink drain, but several years ago after repeated clogging of the disposal I took it out and installed a regular drain in its place. When I made this change I installed a tee connection to drain the DW through. I canít see that the disposal connection was superior to the regular drain with the tee connection for the DW. I will say though I donít miss that POS disposal at all. We compost our food waste and vegetable peels now. And we donít use the DW anymore either. I canít say that I miss either one of these appliances.

I know I know, Iím an AW heretic! But Iím old school. I like to have things done and not have to come back later on to unload a DW that may have one or two items that still need attention for some bit of food that didnít come off in the wash and is now dried on. Plus, I never have to stop and clean some bowl, pan or whatever thats in the DW waiting to be run through a cycle, because I need that item for something Iím cooking.

Every time I leave my kitchen everything is clean, put away and ready for whenever I need it again. And I donít find it to be anymore work than using a DW. Takes all kinds to make the world go around.

I still us the DW though, to store the drainboard, dish drainer and the compost container between uses, keeps these items out of sight until they are next needed.

Now Iíll duck and cover for the fall out.


Post# 1137763 , Reply# 2   12/29/2021 at 13:22 by chachp (North Little Rock, AR)        
No fallout Eddie at least not from me

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We are all different.  Think how boring it would be if we were all the same.  I'm old fashioned about some things but not the dishwasher.  There I am lazy as hell and want to put the dishes in and let them sit.  I am old fashioned about the microwave though.  I don't like the way it warms food.  I don't even use it to melt butter for a recipe.  I like to put a pan on the stove and warm the food.  I think it stays warmer longer too when you do it that way I really enjoy the process of getting out the pan, etc.  I may get some fall out over that.  


Now for the topic of this thread.  The few homes I have built I had a separate drain installed just for the dishwasher.  I feel like that leaves the sink truly independent of the dishwasher.  There is no mess if I forget to run the disposal, etc.

Post# 1137765 , Reply# 3   12/29/2021 at 13:30 by ea56 (Cotati, Calif.)        

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Thank you Ralph!

I agree with you about warming things some on the stove rather than in the MW oven, like meatloaf, meatballs and such. I think that often times the leftovers taste better than getting dried out in the MW. Iíve started doing this more and more myself. But one thing that the MW canít be beat for is making puddings, pie fillings and white sauces in the MW. They never scorch or lump and donít need the constant stirring that making them on the stove requires.


Post# 1137777 , Reply# 4   12/29/2021 at 15:39 by bradfordwhite (East Coast, U.S.)        
noise , steam, and odors

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Draining anything into a tap type drain
whether on a garbage disposal or a sink drain side tap-
that includes things like a dishwasher, a water filtration system, or even an attic mounted furnace/air conditioner condensate drain,
tend to make noise. That can be occasional 'tinking' noise from dripping or the fast discharge from a dishwasher. Sometimes the drain noise from a dishwasher makes more noise than the dishwasher when it's washing. Defeats the whole purpose of sound insulation and a quiet dishwasher.

Then there is the steam, odor, and as previously mentioned, particle build up. Who wants that. That can pit your plumbing fixtures.

Also, if one's sink drain should become blocked or back up, anything connected to it will not be able to drain and crud can then back up into the drain line of what ever that appliance is. yuck.

PVC fittings and piping are inexpensive. Its money well spent for proper, vented drains to each appliance. It's just like having dedicated electric circuits. We don't overload our outlets anymore.

As for those attic mounted furnaces and air conditioners, it's a pathetic job having a 1" line hastily run and dripping from a soffit outside. That's terrible. They need to have a proper 1 1/2" drain line connected to the plumbing system and preferably have a drain pan.

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This post was last edited 12/29/2021 at 16:03
Post# 1137782 , Reply# 5   12/29/2021 at 15:57 by ea56 (Cotati, Calif.)        
Re: Reply #4

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My dishwasher is connected to a vent thats on top of the right hand corner of the sink just like it was before when it was drained through the disposal. It drains more quietly without the DW. And I havenít had to plunge my kitchen sink since I got rid of the disposal.

The last straw with the disposal was during the preparation of a holiday dinner for Easter. I had a house full of people and when I drained the potatoes into the disposal the sink backed up and in the middle of everything I had to get the plunger out, plunge the sink and then sanitize it since who wants to use a kitchen sink that the plunger thats been in the toilet was just used.

The very next day I bought the fitting just like in reply #4, went on You Tube and watched a few videos on how to make the conversion and in an hour it was done. When I had a new DW installed a year later the guy that installed it told me that Iíd done as good a job as any plumber.


Post# 1137787 , Reply# 6   12/29/2021 at 16:21 by bradfordwhite (East Coast, U.S.)        

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I don't use a disposal either.
First if you're on septic, you're not supposed to as the fine particle can clog up the leach field. That's an expensive mistake.

Second, it's a disgusting machine. We put food stuffs in it, it tears it to bits and splatters the walls of the inside of the appliance. There, unless one can meticulously rinse all the gunk away (and no one really can), there it stays. Drying on, stinking, getting moldy, etc.

When I was a landlord all my properties had gds. They are cheap and easy to fix and replace, I'll give them that. I used to get ISE or Badger disposals at Menards for like $30. But several times all I needed to do, after dismounting it, is take the screws out and remove whatever stupid things were attempted to be put into it. One time I removed about 20 pennies that some how fell in.
Without the pennies in there it worked fine.
But they are Always layered with gunk and no one ever cleans those black rubber things that go in the hole. Even though they are removable and one could soak it in a bleach formula and clean it or put it in the dishwasher.

Third, I compost. Most of my food waste gets broken down naturally to make NEW fresh, fertile soil for my garden and pots.

I eat a lot of fruits & vegetables so there is a lot scrap. Apple cores, banana peels, pineapple waste, the undesirable parts of lettuce brocolli, tomatoes, etc. all go into a container in the freezer for at least 24 hrs.

When that's full it's simply dumped into another container, a bit of water is added, and the lid put on so it can defrost.

Then a couple days later it's layered inside my worm compost bin. A layer of shredded leaves is spread over it. The worms eat it up and turn it into black gold. And no fruit flies and no smell either. It's amazing.

The liquid that leaks down is harvested and poured on plants soil as fertilizer.

Now thats getting your money's worth on your food bills.

Post# 1137788 , Reply# 7   12/29/2021 at 16:36 by bradfordwhite (East Coast, U.S.)        

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"...watched a few videos on how to make the conversion and in an hour it was done."

I'm just curious, what did you do with the disposal?

Was it wired direct or did it plug into an outlet?

Post# 1137796 , Reply# 8   12/29/2021 at 17:06 by ea56 (Cotati, Calif.)        

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Bradfordwhite, I threw the disposal into the dumpster. It wasnít hardwired, there is a dedicated outlet under the sink for the disposal. I believe it was a Badger, I bought it at a now defunct store named Yardbirds.

And you are so correct GDís are filthy! Its next to impossible to keep up with cleaning out all the nasty sludge that builds up in them. I used to take out the rubber top regularly and clean it and reach under the edge an try to get out all that mess, glad I donít need to do this anymore. As for the clogging, potato peels were the very worst culprit for that malady. Iíll never have another disposal again.

We use a plastic Maxwell House coffee can for the daily compostables. And we fill it tightly packed once a day then take it out to the compost bin in our HOA dumpster enclosure. If we had a vegetable garden weíd do what you do and use it that way. I think that putting all that crap into the pipes and using all that precious water to flush it down isnít responsible in light of our current water shortage.

Another plus for no disposal is that thereís more storage space under the sink.


Post# 1137819 , Reply# 9   12/29/2021 at 19:14 by thomasortega (El Pueblo de Nuestra SeŮora de Los Angeles de Porciķncula)        

I'm the opposite.... I can't live at all without a good disposer.

My life is dreadful with the cheap ISE Badger (I call it ISE Clogger) but that's what we have as a rental unit..

Until the day I get really pissed off and decide to buy an ISE Evolution Excell.

Post# 1137823 , Reply# 10   12/29/2021 at 19:32 by rinso (Meridian Idaho)        

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Eddy, every newly-constructed house that my late husband and I moved into had a Badger disposal. It's common contractor quality. And yes, potato peelings would clog one of those things even if there were only a few. We learned to replace them with the better quality InSinkerator models with a much larger motor. But, I still don't put potato peelings, egg shells, or chicken bones and other "hard-to-digest" materials through.

Post# 1138028 , Reply# 11   1/1/2022 at 02:45 by tolivac (greenville nc)        

I have one of those "Moen"disposers with a DC drive motor-use it all of the time-and into a septic tank no less-no problems!And I don't get smelly waste still in the shred chamber.

Post# 1138044 , Reply# 12   1/1/2022 at 09:07 by neptunebob (Pittsburgh, PA)        

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I think that having the dishwasher drain into the disposal might help clean out the disposal and keep the odors down.  If you can catch when the DW is draining, turn on the disposal and it helps clean the upper chamber.  Might still have to clean the disposal manually but not as badly or as often.  I do use the disposal but most vegetable matter goes in compost, really just bits go down the disposal.

Post# 1138045 , Reply# 13   1/1/2022 at 09:39 by eurekastar (Amarillo, Texas)        

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Maybe my reasoning is flawed, but I like the DW draining into the disposal in order to keep it flushed.  When the final rinse is set to sanitize, maybe it helps to keep the disposal clean?  I used to have problems with odor from the disposal until I switched the DW to drain into it.  I haven't noticed odor since then.

Post# 1138050 , Reply# 14   1/1/2022 at 12:22 by IIIJohnnyMacIII (North Carolina)        
I'm A Disposal Fan

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I've got a standard 1/3 HP Insinkerator model 1-83. It's been in the house before I bought the house 13 years ago. I've never had any issues with odors. When I need to use it, I simply run some water and flip the switch. In 1 sec everything is gone. No food or anything is left in the disposal. That's just been my experience.

On the other hand I've seen air gaps get clogged and become a maintenance hassle. Like seen in this video.

Post# 1138052 , Reply# 15   1/1/2022 at 12:44 by mark_wpduet (Lexington KY)        

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My kitchen sink has a vent on the top right and the dishwasher drains through the disposal....I haven't had any clogs from the dishwasher but I have had clogs in the past from actually USING the disposal I stopped using it..When the clog happened, I thought I was going to have to call a plumber because no amount of plunging was was then I discovered a youtube video. In the video they covered the vent before plunging....that worked.

The garbage disposal does get nasty!! Even if not used...Every few months I put rubber gloves on and pour cleanser down in there and scrub the sides underneath the rubber....It's so gross... and even with me keeping the sink clean daily with hot water......the disposal area still will get gross over time on its own

Post# 1138054 , Reply# 16   1/1/2022 at 13:03 by ea56 (Cotati, Calif.)        
Re: Reply#15

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Mark, I discovered the trick of covering the DW vent with a wash cloth when plunging on my own, as when Iíd plunge the GD water would come out of the vent. I also found that putting the GD stopper in the drain of the sink next to the GD side helped make the plunging more effective. Sounds like your experience with the sludge in the GD and having to frequently clean it out mirrors mine.

To each his own, but I lived most of my life without a GD and I donít miss having one a bit. I imagine if Iíd had a power powerful and expensive GD then maybe I wouldnít have experienced the frequent clogging of the kitchen sink drain. However, replacing the GD with a conventional drain solved the problem. Havenít had a clogged kitchen sink since nor have had to clean out a nasty, sludge filled GD.


This post was last edited 01/01/2022 at 13:19
Post# 1138141 , Reply# 17   1/2/2022 at 03:39 by askolover (South of Nash Vegas, TN)        

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I bought a round toilet brush at dollar perfectly fits down into the disposal.  I sprinkle Comet on it, stick it down and go to business.  Plus, we regularly pour a little bleach water down.  No smells!  Back when dishwasher detergents all had chlorine, my mother's drained into a disposal.  It never smelled either...kept it cleaned out.

Post# 1138169 , Reply# 18   1/2/2022 at 13:41 by bradfordwhite (East Coast, U.S.)        

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The problem with the disposer is not so much the grinding plate being dirty. When ever one pours something into the disposer or a dishwasher drains into it, it flushes the plate and supposedly that which is beneath it.

The main stink problem is the walls of the chamber.

When the plate grinds, it throws gunk all over the chamber and the walls get covered.

If people could see how bad it is, most would surely clean up the mess.

If ever anything greasy has been put down there, that grease can get on the plate, under the plate, on the walls.... and gunk will stick to it. No household chemical cleaner is going to remove layers of grease. That needs to be scraped off.

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Post# 1138171 , Reply# 19   1/2/2022 at 13:58 by bradfordwhite (East Coast, U.S.)        

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yep, plunging one side while covering other side AND if you have a dishwasher vent, either have someone hold a towel over the holes or wrap it with a plastic tape temporarily so no air can escape when you plunge.

I had an aunt that didn't get the importance of covering the air hole in her backed up bathroom sink before plunging.

So I told her to hold her finger over the hole and keep a tight grip, then I pushed the plunger into the contour of the sink where the drain is with one hand, then plunged (carefully) with the other, and that pushed blockage out.

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Post# 1138172 , Reply# 20   1/2/2022 at 14:04 by bradfordwhite (East Coast, U.S.)        

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The worst is when oil or gunk has built up on the inside walls of pipes BETWEEN a sink and the trap.
This will smell and attract bugs. I had one rental where roaches were living in the drains because even though the drain line worked, the roof of the pipe had gunk they were eating.
So poured a cup of bleach in and covered the drains with a plastic cover and taped it in place, then let it sit over night. They couldn't get out and died. Then took the pipes apart, took them outside and with a stick removed the heavy gunk, put the pipes in the dishwasher (vertically) and cleaned them up and put them all back in place. No cost fix to a stinky, buggy problem.

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Post# 1138176 , Reply# 21   1/2/2022 at 14:39 by Yogitunes (New Jersey)        

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Common sense 101:

common issues with backup is not making sure your plumbing system can handle waste from a disposer, and making sure your system is thoroughly cleaned out before installing one...

there are models for septic use with no issues.....

and most important, you can't bring a YUGO to a Nascar Race, and then wonder why you lost!...

more times than I can count is seeing people replace a 300.00 disposer with a 50.00 Badger, and wonder why it doesn't perform the same!....just boggles the mind....

Post# 1138178 , Reply# 22   1/2/2022 at 15:55 by qsd-dan (West)        

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I periodically clean the disposer by running a small stream of water while dumping a mass load of ice down the drain. When the water stream to dumped ice ratio is properly balanced, the drain pipe will momentarily plug from an ice lock and the disposer will shoot out a slushy stream (reminds me of the slush puppy beverage I got as a kid) from the opening as it scrubs the blades and chamber walls from bottom to top. Too much water and the whole works go down the drain without scrubbing the chamber walls. Not enough water and the ice gets stuck to the walls of the chamber, the scrubbing action halts, and the drain gets ice locked.


Sort of hard to describe the process but I discovered this by accident over 30 years ago while dumping a bunch of watery ice from an ice chest down a running disposer.


Running dry ice down a disposer was good fun as a teenager, lol.

Post# 1138179 , Reply# 23   1/2/2022 at 15:56 by bradfordwhite (East Coast, U.S.)        

This post has been removed by the member who posted it.

Post# 1138180 , Reply# 24   1/2/2022 at 15:57 by bradfordwhite (East Coast, U.S.)        
The weekend DIYer GD install

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They install a NEW weirdly deep sink that's like 10-12" where the old sink was 7". But the drain on the wall was originally figured for that 7" deep sink.

If you have standing water in your gd these hilarious, and no doubt stinky, installations show you why.

CLICK HERE TO GO TO bradfordwhite's LINK

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Post# 1138198 , Reply# 25   1/2/2022 at 18:46 by Yogitunes (New Jersey)        

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yeah, I ran into an application like that when installing a disposer at the country house....fortunately enough, I was able to run the pipe down through the floor and reconnect to existing plumbing....

but how many installs look exactly like the one posted...

as usual, personalities you can figure out in an instant, but understanding why people do the crap that they do will forever puzzle me....I could write a book!

Post# 1138199 , Reply# 26   1/2/2022 at 18:51 by mark_wpduet (Lexington KY)        

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I'm not sure what mine is. I think it's whirlpool but probably not made by's from 2004...if I didn't have it, I wouldn't miss it at all. Wanna know what caused mine to clog? Green Lettuce...I had some in the fridge that had been washed in a container and all of it didn't get used and it got slimy...big mistake. Never again. The only thing that goes down my disposal now are just bits of food, crumbs....I still turn it on if there's a bean or a noodle that goes down or something like that...but that's it.

If I throw food out that I know is going to smell......I put it in a ziplock bag, seal it, then throw it in the trash

Post# 1138201 , Reply# 27   1/2/2022 at 19:03 by bradfordwhite (East Coast, U.S.)        

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yeah, if one has a basement or access below the kitchen I figure the easiest thing to do is drill a hole through the floor of the cabinet into the basement and run a new drop and use the existing wall connection as the vent. It's far easier than pulling apart the wall and lowering or installing another "Y" to connect into.

Post# 1138213 , Reply# 28   1/2/2022 at 20:18 by GELaundry4ever (Killeen tx USA)        
dishwasher drainage

The dishwasher drains directly into the drain line at my dad's house. You can hear the water emptying out the machine when the drain pump starts.

Post# 1138293 , Reply# 29   1/3/2022 at 16:04 by lakewebsterkid (Dayton, Ohio)        

You know, itís funny. One set of grandparents dump everything down theirs. They have an old ISE and never any issues. The other grandparents forbid anything from entering their GD. The result? Theirs clogs fairly frequently with an older ISE as well. I agree the plumbing makes a big impact, too! Our rental has a newer badger that does well. The dishwasher dumps into it without an issue. No smells likely with the Cascade Fryer Boil Out.

Post# 1138499 , Reply# 30   1/5/2022 at 11:29 by vacerator (Macomb, Michigan)        
Our kids drains

into a trap in the basement, and the main waste stack, below the dishwasher, which is next to their stove, not near the sink.

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