new 10' deep sink and disposal waste drain... help!

13 years ago

I may be in trouble! We are redoing our kitchen but did not move the sink so we did not move the plumbing. We did get a new, 10" deep undermount sink and plan on granite countertops. Cabinets are 34.5" tall. At the sink wall, our waste drain pipe is 16.5" from the floor. Our new big, deep single basin undermount sink is 10" deep - so it will sit 24.5" from the floor (34.5 - 10). Most garbage disposals have the outlet and downward facing waste pipe at about 10" from the top of the disposal which sits at the bottom of the sink - and then there is a "U or P-trap" that attaches from the outlet to the waste drain.

Question: using our configuration, I am afraid the waste drain is 2" too high. Is that ok? Not ideal but would it work? Or do we need to have this moved now BEFORE the cabinets come in? Or do I need to purchase a sink that is only 8" deep?

Featured Answer

paulparkercpa

8 years ago

I hope my post will save someone from the grief we endured during our kitchen remodel. We had a similar problem - wife wanted new counter tops and deeper sinks. Our "Granite Guy" (who did nice work on the counter tops, back splashes, etc) made no preliminary drain height measurements - oops! - prep sink garbage disposal cannot be reconnected to drain. A prep sink without a garbage disposal is pretty useless. After "Granite Guy" had basically given up and wife was ready to call lawyer - I looked under the cabinet myself. The distance from the bottom of the new sink to the center line of the drain was about 7 inches, but the distance from the top of the old garbage disposal sink connection to the center line of the garbage disposal drain was just over 8 inches, and water will not run uphill. I looked at about a half dozen online garbage disposal installation instructions and finally found a garbage disposal that had a significantly shorter distance from the sink connection to the drain (6 inches): the ISE Evolution Compact 3/4 HP, but it was a special order. A little more looking revealed that the ISE 5/8 HP model, although not described as a "compact", also had the same basic dimensions and was available at our local store. I also discovered that some of the small Badger units had a distance just slightly over 6 inches and were half the price of the ISE units, but I took no chances and used the ISE 5/8 HP unit. The disposal drains well and is very quiet. Happy wife = happy life.

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Comments (6)

hendricus
13 years ago
Fix the pipes. If you want to have a 10" deep sink you will not be happy to settle for less. Don't go for just a couple of inches either, go more because it is easier to lenghthen the pipes than shorten them again.
homebound
13 years ago
I think you're about 1" shy. If that turns out to be the case, you would have water not draining out of the bottom of the disposer.

But don't take my word on the calculation. You can try to use this thread as a rough guide since I went through the same problem with a drop-in sink.

http://ths.gardenweb.com/forums/load/plumbing/msg0309101724748.html
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We had this exact problem. The GC, who is also a plumber, didn't pay attention to my sink specs when he installed the drain pipes. My sink is 10" deep, plus the 1.5" counter, so the drain is much, much lower than in my old 7" deep overmount sink. When the disposal was first installed, we had almost an inch of water standing in the bottom of it unless we ran it for about 30 seconds after the water was turned off. Obviously, this was unacceptable. We complained and he came back and fixed it in less than an hour. He just needed to lower the point where the drain pipe for the disposal met the main waste pipe in the wall. It has worked fine ever since. He offered to pay our cabinet guy to make a panel to patch the place where he had to cut further down in the back of the base cab. I haven't taken him up on that yet, but I may.
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Anita, that's too bad that your disposal isn't working as well as you'd like. I guess on the bright side, it has a great warranty, and as a percentage of your total kitchen re-do (SO gorgeous BTW!), it's not so much $$ invested. In my home growing up, we had a batch feed disposal, and it was the only kind I knew until I moved out of the house. I had a rental apartment once with a continuous feed disposal. I never really got used to it, but it's hard to change habits that formed from childhood. In my home now, I have the Kitchenaid 1 hp batch feed, which is actually made by Insinkerator (in their factory in Wisconsin). I think though, that the type of disposal someone prefers is personal taste and how s/he likes to work in a kitchen; there is no right or wrong choice. I agree with Buehl that one of the continuous feed's advantages is that you just feed the disposal continually which is convenient (although my disposal's chamber is so large, I rarely have to run it more than once). A disadvantage of a batch feed is that it takes up A LOT of room under the sink. Having said that, I do feel that the "ick factor"--and this is just MHO--is greater with the continuous feed style cause of the clammy flange. You are either having to push food through the flange with your hand or a utensil (I guess Waste King has a tool just for that purpose), or slide your wrist past its clammy surface to fish something out. Regarding brand, I used to say that Waste King was really great, but I think they have changed recently. About 1-1/2 years ago Waste King moved their manufacturing from the U.S. to China. That likely enabled them to lower their costs significantly to be able to sell a disposal at Costco for $79 when that same model when made in the U.S. used to sell for $179. In that same vein, Waste King used to have an entire page on their website devoted to the fact that their disposals are septic-tank safe. That page is no longer on their website, perhaps because the China-made disposals can no longer do that. There are people on this forum who love their Waste Kings, but I bet they have the older ones that were made in the U.S. Anita, my advice to you is that if your Waste King disposal is REALLY bothering you, switch it out for the Insinkerator Evolution Essential which is also a continuous feed style. Donate your Waste King to Habitat for Humanity, or sell it on Craig's List. I am saying this because you are going to be using the disposal every day, likely several times a day, and if you hate it, why ruin the experience of your lovely new kitchen with an irksome disposal. You already have the switch hook-up, so it wouldn't make sense to change to a batch feed style, and the Insinkerator is a well-made model, and quiet too. Just my $.02. Here is a link that might be useful: Insinkerator Evolution Essential Disposal
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lazypup
13 years ago
I think if you take the time to analyze the facts your answer will be a no brainer.

Fact- A kitchen makeover is without question one of the largest and most expensive projects you can undertake in your home.

Fact-The sink is without question the singular focal point of the kitchen. Almost every time you go in the kitchen, regardless of what the reason, you will ultimately end up at the sink if only to grab a glass of water.

Fact- If you have your heart set o a 10" sink and settle for an 8" sink it will forever be a source of irritation and contention, one which you will confront dozens of times a day.

Fact-If you are changing all the cabinets you will already have easy access to the wall and changing the drain line is no big deal.

Fact-If you install the 8" sink now, then later decide you really want the 10" sink it could prove nearly cost prohibitive to make the necessary changes to the drain lines.

Now let us consider what would be required to lower the drain while you have access to the wall.

In a best case scenario when the fixture arm enters the wall it is connected to a vertical line by means of a sanitary tee. In that case it would be very easy to cut the line, lower the tee to the desired level and reconnect the line.

In a worst case scenario the waste arm enters the wall then turns horizontal and runs through the wall to a point were it connects to a vertical stack. The question then becomes how far does the horizontal line travel through the wall?

Under the IRC a kitchen sink drain line is an 1-1/2" line and it is allowed to run a maximum of 6' from the trap weir to the vent opening. Allowing that there is generally about 12" from the wall to the trap that means that the line could run up to 5' horizontally in the wall.

Under the UPC we are required to use a 2" diameter drain line but the total developed length from trap weir to vent opening of a 2" fixture arm is limited to only 5' so we could anticipate a maximum of 4" horizontally in the wall.

In all probability the portion of the wall that you would need to open up will most likely be covered by the cabinets when all done, therefore when you open the sheet rock it would only require a simple patch with one coat of mud & tape to prevent bugs from entering. Not a big deal here.

The question then becomes how much should you lower the line? From your preliminary calculations you determined that you need approximately 2" however, from my experience it is much easier if we allow ourselves plenty of room, therefore I would lower the arm at least 4 or perhaps 5". Keep in mind that code will allow up to 12" vertical drop from the finished sink opening to the water level in the trap.
dlr98004
Original Author
13 years ago
Thanks for all your suggestions. We are ripping open the wall and replumbing the drain. Better now than after cabs and granite goes in!
rkmannan
8 years ago
Seeing as how this is an older discussion, I am curious about how you handled it. I have a similar situation, but by raising the cabinets, I can end up with .5 to 1" slope. Just how much slope do you need? I understand that the disposal MUST be higher than the drain, but I can't find any info on how much higher. Is it the same rules as the slope for the drainpipe? minimum of .25"/ft? How did yours turn out?

new 10' deep sink and disposal waste drain... help!

paulparkercpa

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hendricus

homebound

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new 10' deep sink and disposal waste drain... help!

paulparkercpa

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hendricus

homebound

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