Waste Pipe too high for Waste Disposal?

[Drizzt]

I just have a new cabinet installed and in the process of having the waste disposer and new P-trap installed. After having about 5 plumbers/handymen giving price quote for this particular job amongst other things in the home, it just dawn to me that the waste pipe height on the wall appeared to be quite high and might pose a problem. I decided to put in my waste disposer, which is relatively small in itself, in order to take these photos.

Is it absolutely necessary to move the waste pipe down lower? Or would it be fine as is? At current height, it looks like the trap would have more than 4 inches drop and the outlet is higher than the waste disposal's outlet.

I estimated it needs to be moved at least 6 inches lower (or at least 10.5 inches relative to the reference height, which is the bottom of the sink). Strangely, none of the 5 plumbers/handymen even bat an eye to the problem. When I asked for a price estimate to move the pipe lower, I was told it would cost $1200 to just open it up from the garage side to look with no guarantee it would be moved. My head start spinning after this. Any advice would be appreciated.

Youtube and various websites oddly don't ever talk about this particular issue?!

 

[Reach4]

Is it absolutely necessary to move the waste pipe down lower?

Yes, if you want a disposal, or you can get a sink what is shallower. Looks like the amount you need is closer to two inches. You need the middle of the trap adapter in the wall to be lower than center of the disposal discharge by -- not sure-- maybe 3/8 inch or more? Not important at this point unless you would consider sink shopping, and that is not likely to happen.

Why go in from the garage rather than under the sink?

You knew your area was expensive... what is typical -- 1.8x the bulk of the country maybe? Oh wait, that was not for the work -- just to take a look. You might be higher than Manhattan.

Seriously, its better for the environment to put your food waste into the garbage. Besides the sewer lines and plant, it takes more water with a disposal. Even better to have a compost pile, but that's hard. Food in refuse bin is easy.

This topic has been discussed several times here. A self-leveling laser level is nice for measuring and photos, but not needed for your situation. You are not close.

 

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[John Gayewski]

The only other option would be a pump. Your better off lowering the pipe.

Just out of curiosity. How high is the pipe relative to the finished floor of the kitchen?

 

[Drizzt]

The only other option would be a pump. Your better off lowering the pipe.

Just out of curiosity. How high is the pipe relative to the finished floor of the kitchen?

The pipe appears to be 14.5 inches from the bottom of the cabinet + roughly 6 inches + 3/4 inch of plywood that raised the cabinets for dishwasher = 21.25 inch roughly

The reason I thought it needed to be moved 6 inches lower was because the waste disposer manual had a page that showed the waste pipe needs to be 10.5 inches from the top of the waste disposer.

 

[Reach4]

Another thing: having the disposal dead center on the trap adapter will complicate things. Picture the path of a trap. So your planning, even if you drop the sanitary tee, will need the depth-coordinate involved in your planning.

If they brought the new trap adapter in at an angle, that could help things.

Your wall construction seems non-conventional, like metal plates held on with drywall or deck screws. Before that cabinet was put to the wall, it might have been easy to unscrew the plates, see what you have, and add in a new sanitary tee lower. Can you remove the switchplates and pull the cabinet away now?

When I had to replace a sanitary tee in the wall, I paneled the back of the cabinet with flooring to close the hole.

 

[Drizzt]

Another thing: having the disposal dead center on the trap adapter will complicate things. Picture the path of a trap. So your planning, even if you drop the sanitary tee, will need the depth-coordinate involved in your planning.

If they brought the new trap adapter in at an angle, that could help things.

Your wall construction seems non-conventional, like metal plates held on with drywall or deck screws. Before that cabinet was put to the wall, it might have been easy to unscrew the plates, see what you have, and add in a new sanitary tee lower. Can you remove the switchplates and pull the cabinet away now?

When I had to replace a sanitary tee in the wall, I paneled the back of the cabinet with flooring to close the hole.

Unfortunately, the cabinets are all set with countertop already installed. The only option is to cut more of the back of the cabinet out and remove or cut the metal plate covering. I'm terrified at the thought of going through the wall from the garage side as that would violate the seal/fire code. The new T will definitely need to curve to the left as that's where the air gap and dishwasher are and likely where the waste disposer will be rotated to. We never intentionally dump food down the drain but the Mrs wants the waste disposer to be sure things don't clog.

I just measured again and the bottom of the waste pipe is 14 inches above the bottom of the cabinet. Would moving the pipe 6 inches lower(8 inches above bottom) to meet the distance from top of waste disposer as laid out in the manual cause any problem?

 

[Tuttles Revenge]

The first thing I would do is to shine a light into the drain and see whether the drain goes Down or to the side. If it goes down then the problem becomes much easier. If the drain goes to the side, then you might be getting the work done cheaply at $1200. If the drain runs horizontally to the cabinet through several studs, then the walls need opened up and new holes drilled and depending, might have to be fire rated materials such as copper or cast iron depending on SF codes.. unless you're out of The City.

But definitely can not install that disposer at those elevations. You will have standing water in the disposer All of the time.

 

[John Gayewski]

I usually install a kitchen drain 18" above the floor.

 

[Jeff H Young]

No one bats an eye , dont know why they would ? common screw up , You had 5 guys come take a look for some reason and only one price. price sounds high .

I can only guess from here the fix could be 2or 3 hours it could be more it might be conciderbly more and determined not practical.
Nothing wrong with wanting a disposal, your choice
Id likely open front and lower it , there are several common ways this could have been plumbed some would allow for an easier fix than others

 

[Jeff H Young]

the cabinet is already hacked to hell might as well go from sink side if possible . as Tuttles said a flashlight likely reveal if there is a tee in a vertical position (that's what we hope for). when finished re skin the back of cabinet. a lot of kitchen cabinets don't even have a back on them but cutting them up doesn't look good.
didn't you talk to the 5 tradesmen that came to the job?

 

[Reach4]

The new T will definitely need to curve to the left as that's where the air gap and dishwasher are and likely where the waste disposer will be rotated to.

The lines to/from the air gap and disposer are flexible.

The first thing I would do is to shine a light into the drain and see whether the drain goes Down or to the side. If it goes down then the problem becomes much easier. If the drain goes to the side, then you might be getting the work done cheaply at $1200.

Good point. I was presuming vertical. Is there a window above there? That would make horizontal fairly likely. But if there is a garage on the other side of the wall, a window is unlikely. Yet you can have horizontal with no window.

It looks to me as if you could unscrew those two metal plates and look in.

While things are open, you might look at whether you would want to upgrade the two stop valves.

 

[Drizzt]

The first thing I would do is to shine a light into the drain and see whether the drain goes Down or to the side. If it goes down then the problem becomes much easier. If the drain goes to the side, then you might be getting the work done cheaply at $1200. If the drain runs horizontally to the cabinet through several studs, then the walls need opened up and new holes drilled and depending, might have to be fire rated materials such as copper or cast iron depending on SF codes.. unless you're out of The City.

But definitely can not install that disposer at those elevations. You will have standing water in the disposer All of the time.

Great advice on shining light inside and taking photos inside. Was able to see that the pipe is vertical. Interestingly, there's a niche above the sink so it probably curves around at some point. I can climb onto the attic to spot any vertical pipe above the niche if necessary. I got a quote over the phone and a second coming this afternoon for a quote.

 

[Drizzt]

The lines to/from the air gap and disposer are flexible.


Good point. I was presuming vertical. Is there a window above there? That would make horizontal fairly likely. But if there is a garage on the other side of the wall, a window is unlikely. Yet you can have horizontal with no window.

It looks to me as if you could unscrew those two metal plates and look in.

While things are open, you might look at whether you would want to upgrade the two stop valves.

Forgive my ignorance but the stop valves can be upgraded? What would the upgrade be called if I want to future proof? Might as well get it done with the cabinet cut up and the metal plates off.

 

[Reach4]

Forgive my ignorance but the stop valves can be upgraded? What would the upgrade be called if I want to future proof? Might as well get it done with the cabinet cut up and the metal plates off.

Show a sharp side view of where one of the current stop valves connects to the wall. Looking for the type of interface. Also, can you tell what kind of pipe they connect to? copper, steel, or what? Steel attracts a magnet.

So if those are compression connection at the wall over copper, the upgrade would be to replace the valves with new mini ball valve valves or other quality 1/4 turn valves.

 

[Jeff H Young]

Drizzdt, judging by your photo, it looks like your fix will be relatively easy basically cutting the vertical pipe in the wall removing the T and replacing it with a new one lower and a few couplings. Pretty easy stuff . I'm not judging what your cabinet looks like but I would like to remove the angle stops and extend stub outs with caps. have you or your finish carpenter patch the back wall of cabinet and then install new shut offs with chrome escutions and complete the installation .
Again I think this is all doable from undersink.

 

[Terry]

I've been installing my kitchen drains at 16" off the floor since seeing so many 10" deep undermount sinks.