# Run Dishwasher drain under Floor?



## psuarmy (Oct 8, 2013)

My Dishwasher is around the corner in my kitchen from my sink. I am having a really hard time running the drain. My idea is to drill a hole in the floor and run it right under the floor. I will drill holes through the joists just under the floor to the sink. When I get there I will raise the line to the high loop to a level with the top of the dishwasher the down to the tap in the drain before the P-trap.

The dishwasher is 30 inches high. The instillation guide states that the high loop needs to be a "minimum" of 30 inches. The drop from the high loop needs to be a "minimum" of 10 inches from the top of the high loop. I have 15 inches. 

The whole line will be about 10 feet long. My dishwasher is a Samsung modelMT400RHS/XAA which seems to be a mid to upper level dishwasher.

My concern will be that there will be too much water left in the line with it going below the floor. There will only be a 36 inch rise which should be OK. I contacted Samsung and was told that it would be OK, but the guy I was talking to didn't seem very knowledgable. 

I know that there is always water in the line in a dishwasher drain line, but will the below level drop cause excess water to backflow into the dishwasher and smell?

I appreciate any and all advice. I am not as concerned with "code" as I am with what will work. I always try to balance doing it properly (not half assing it) with making it work without excessive cost or work. If something is OK, but not the "new construction" method I am OK with that. If it is a "can get away with it" fix I need to know.

Thank you very much.


----------



## lanny (Oct 8, 2013)

Ya what I will be doing is installing my dishwasher right beside my sink and not going into the floor to my drain but where my dish washer was before they had the rise or lift right behind the dishwasher and after that they plumbed it about 15 ft and up the the pee trap with rubber hose and it seemed to work well like that


----------



## gregzoll (Dec 25, 2006)

psuarmy, why can you not install the Dish Washer next to the sink? If you do it the way you want, you need to check your local code office, to make sure that a "Chicago Loop" http://en.wikipedia.org/wiki/Chicago_Loop_(plumbing) is allowable in your jurisdiction. Video showing rough in for the vent. 
http://youtu.be/fxmPwH4dxpk


----------



## psuarmy (Oct 8, 2013)

Gregzoll: I would love to move the dishwasher next to the sink. Unfortunately my kitchen is so small there is not enough room to install it next to the kitchen, and I don't have enough money to completely rearrange everything right now, haha. I am not trying to install a "Chicago loop". Here is what I am looking to do:








This is from my instillation guide on how the want it done. I don't have an air gap instillation and can use this method. I just want to drop the hose a few inches under the floor.

please excuse the foreign language on the pic. I took the pic from the wrong part of the manual.


----------



## djlandkpl (Jan 29, 2013)

You could always put the high loop on the back of the DW and that would prevent water from backing up. My DW came from the factory that way. My only concern would be prematurely wearing out the discharge pump since it will be pushing against 10 feet of water.


----------



## psuarmy (Oct 8, 2013)

djlandkpl:

There is no room to have the loop at the dishwasher. The unit is a very tight fit in the cabinet. I would need to leave the unit stick out about an inch to allow for it. Here is how things look in my kitchen. Right now the unit is just placed in its spot.









I don't really need 10 feet of drain line, but the dishwasher hose is 5 feet and the extension is 5 feet. Is there something I can use instead of using the extension? I went to my local plumbing supply and to Lowes and could not find a regular hose that would connect to the coupler I have and to the connector at the drain. If anyone know what I can do for that I can probably eliminate a foot or so to help with the length.


----------



## wkearney99 (Apr 8, 2009)

If it's an interior wall then why not just cut out a chunk of the drywall behind the dishwasher to gain some added depth back there for the loop. 

Or if that corner cabinet has a lazy susan inside then run the loop high up through the back of it. If it's an open square in there you'd be fine. If it's got the enclosed circle then you'd have a bit more work, but it might be possible to fish the hose around the back side of that inner wall.

If you've got access from below then I'd also wonder about just running the drain down to somewhere else on the waste line. But I don't know how the rest of it's laid out and what code would have to say about that.


----------



## djlandkpl (Jan 29, 2013)

wkearney99 said:


> If it's an interior wall then why not just cut out a chunk of the drywall behind the dishwasher to gain some added depth back there for the loop.
> 
> Or if that corner cabinet has a lazy susan inside then run the loop high up through the back of it. If it's an open square in there you'd be fine. If it's got the enclosed circle then you'd have a bit more work, but it might be possible to fish the hose around the back side of that inner wall.


I agree with Bill.


----------



## wkearney99 (Apr 8, 2009)

wkearney99 said:


> If it's an interior wall then why not just cut out a chunk of the drywall behind the dishwasher to gain some added depth back there for the loop.
> 
> Or if that corner cabinet has a lazy susan inside then run the loop high up through the back of it. If it's an open square in there you'd be fine. If it's got the enclosed circle then you'd have a bit more work, but it might be possible to fish the hose around the back side of that inner wall.
> 
> If you've got access from below then I'd also wonder about just running the drain down to somewhere else on the waste line. But I don't know how the rest of it's laid out and what code would have to say about that.


I agree with dj's concern about making the discharge pump work too hard. Modern appliances aren't as over-engineered as they might have been in the past. So any time you come close to, let alone exceed, the manufacturer's recommendations you're asking for trouble.


----------



## psuarmy (Oct 8, 2013)

It might be possible to cut a hole in the back of the cabinet and run it along the back. I could then cover it with molding to protect it. The cabinets are open. I will look into that possibility. I will still have the problem with the hose not being long enough. I would need an extra 2 to 3 feet to get to the sink and make the loop. which means I would have to coil a few feet of hose and the pump will still have to push 10 feet. Does anyone have any suggestions on how to make a variable length extension hose?


----------



## djlandkpl (Jan 29, 2013)

You should be able to get a drain extension. It would go between the DW and the existing hose. If you can get the hose behind the cabinets, go up high in the corner cabinet. This will give you your high loop and the pump won't have to work as hard as gravity will move the water to the drain.


----------



## broox (Nov 30, 2010)

What is up with those pink curtains?
Anyway, run the hose through the back of the corner cabinet, or just install a new p-trap in the basement/crawlspace for the DW to drain into.


----------



## psuarmy (Oct 8, 2013)

Haha, the curtains are actually red. Direct morning light and cell phone camera made them look pink. Besides I am in charge of installing my wife is in charge of decor. She actually does a pretty good job. 

The drain from the sink drops straight down in the basement to the floor and is completely exposed. I could tap into it. It is not normal drain pipe though. It is regular 2 inch white PVC pipe. I thought there might be a code issue having it drain that way. But I am open to anything that works and is not ugly.

I think in back of cabinet is best option. But I will still have the problem of either a hose that is too short or extending it too long. Still looking for suggestion of variable extension hookup.


----------



## TheEplumber (Jul 20, 2010)

Drill high in the cabinets- just below the top, behind the drawer. This will protect the hose.
Get some 7/8 radiator hose to extend the length.
Use a 3" piece of 3/4 copper pipe with hose clamps as a coupler to the factory hose.
My HD carries the hose.
Getting around the lazy Susan might be tough but this is the method used around here

Sent from my iPhone using DIY Forum. Watch out for spell check


----------



## psuarmy (Oct 8, 2013)

I will look into adapting with copper pipe. I will have to see how it connects to the p-trap adapter. 

Thank you everyone for your help so far. The activity and speed of help was unexpected.


----------



## dabeast (Apr 2, 2013)

Is your basement open? Could we get a picture below the kitchen of the sink drain and/or rafters?


----------



## psuarmy (Oct 8, 2013)

I was able to figure how to make an custom length extension. I was able to find a coupler that will fit both inside the drain hose and inside a reinforced braided rubber hose. I also got a new adapter for the sink drain that will fit inside the rubber hose.

I also found out that the dishwasher drain has a check valve in it. So water will not backfill into the unit itself. I am going to try to run the line in the back of the cabinet. I got a piece of crown molding to cover the line once I am done.

I will post back when I am done.


----------



## Diymonkeyy (Jul 13, 2018)

Did it work?
I have the same issue to install a DW next to a lazy Susan... installers said Bosch doesn’t have a strong pump as a kitchenaid, or Ge do. What’s the brand of your DW?


----------

