Well, naturally my kitchen drain pipe is too high for the garbage disposal

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Moby

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Recently I discovered that there was a leak behind my kitchen sink, opened up the back of the cabinet and discovered a heavily decayed galvanized drain pipe leading to the cast-iron stack. We replaced it with PVC and closed up the back.

We did not change the height or realize at the time that it is a problem, nor could we have changed the height without extreme difficulty and probably disastrous failure. I guess we'd have had to replace a section of the cast iron pipe with PVC, all while crouched under the sink and after somehow crawling to the outer edge of the attic to brace it from above. I mean I guess it's not too late to do that, but I have no hope that this would not result in horrific catastrophe, whether in the form of property destruction or loss of a valuable finger or eye.

The previous trap under the sink was kind of grungy, so I bought a new one. It was only upon installing it that I realized that the previous configuration had used an extension tube to connect the trap to the waste outlet coming out of the back of the sink and that this was because the waste discharge of the disposal is significantly lower than where the drain enters the wall. My SO decided to configure things a bit differently to accommodate this: he put the trap backwards and used what should have been an outlet as an extension, then used the extension as the outlet, fitting it into the pipe coming from the wall. When I noticed this, I figured it would not work, but it seemed to be working, so I left it alone. Today, it started leaking from where the outlet-functioning-as-extension and trap are joined, and the reason was obvious: the standing water in the trap extended past this point.

The thing is, the disposal set-up did not leak before and drained fine, did not smell, etc. I don't know how it managed to defy gravity, but somehow it did. Occasionally you had to turn the disposal for a second or two to get the sink to drain, but this was not a problem. This disposal's predecessor did not last as long as it should have, probably from having standing water in it, but it did last around around 7 years.

What are my options here? I have seen a suggestion of using a grey-water pump to pump the water up to the outlet. Is this feasible? Has anyone seen such a set-up in action or have a pump to recommend?

I am aware that garbage disposals are bad, cause problems, etc., but not having one is not a viable option. Unfortunately, people in my family simply cannot be counted on not to just cram food down the drain or follow even the most basic instructions regarding daily living. There are no words or actions that have any hope of changing their behavior, so a disposal is essential. If I have to buy a new one, even annually, I can live with that, but I can't have water leaking under the sink.
 

Jadnashua

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A garbage disposal acts like a pump when it is running, so that's why it moved things. It will often cause problems by not fully evacuating the pipes when it has to pump uphill, though, and that can shorten the life of the pipes.

Does that vent line go out through the roof above the sink? If so, you could support it at the roof to keep things from falling down.

About 7-years for a GD that is used is about it anyways...while it may still work, the blades are getting dull, and it won't grind up the bits as well, potentially leading to blockages. Depending on how far off it is, a new GD might be at the right height (probably not, though!). The right answer is to lower the fitting in the wall. Now, if this is a two bowl sink, and you could raise everything to the smaller bowl (if it's that type), that may work out well, too.
 

Moby

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This garbage disposal is only a few months old. It's predecessor is the one that lasted 7 years. Rust ended its life, but really I wouldn't have expected it to last much longer anyway.

I don't think a new disposal could solve this. The pipe from the wall is only about 1 1/2" from the bottom of the sink.

The sink is not a double bowl, so no hope there.

The vent does go through the roof, but a big cast iron pipe has to be very heavy. I don't think trying to brace it from the exterior would end well. Right now I have a fully functional bathroom and I'm not looking to change that.
 

Moby

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image.jpg
 

Moby

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Eh, I'm just going to put it back how it was and hope for the best. It worked before, so it can again. I hope.
 

Jadnashua

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There will be standing water and waste in the disposer causing it to potentially smell and if there are any rustable or corrodible parts...the constant immersion will shorten its life. The only reason it drains is that the thing is a pump when it is running. Normally, it would be REALLY slow as the sink is a bit higher than the outlet to the wall. The adage ***** doesn't flow uphill comes to mind.
 

Geobrick

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What's on the other side of the wall? Is it an outside wall or is it just a wall in a hallway or in another room. The reason I ask is it might be really easy to access the pipe and redo the rough in from the other side. Dry wall is pretty easy to open and patch (for everyone but me).
 

Moby

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The other side of the wall is the tiled shower. This is, unfortunately, the only accessible side and it's not easy. It could be possible, but the risk of ending up having to try to remove the sink cabinet and ending up having to replace the granite countertop is not trivial.

Like I said, it has been plumbed this way for years without smells (I normally run the water for a bit after running a disposal and I put citrus peels down it pretty often, so maybe that's why) and the previous disposal lasted as long as disposals should, so I think that leaving it as is is the only reasonable solution right now. Even if it ate a disposal a year, they are a small fraction of the cost of repairing the potential damage attempting to lower that pipe could incur.

The trap is back together with the extension tube and not leaking, so I'm going to hope it stays that way and put a permanent fix off for a bit.
 
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