dishwasher drain into Disposal

[John C Hansen, LEED AP]

What is the principle behind the statement that the dishwasher should not discharge into the disposal? Yes, there is a drain loop, so that is not the issue. Around my area, many state licensed plumbers would make the connection of the Dishwasher drain into the "Garbage Disposal" (food waste disposal) in new constructiion and the inspectors passed it. What principle informs us that it should not be done that way? Has the code changed?

[Gene South]

What is the principle behind the statement that the dishwasher should not discharge into the disposal? Yes, there is a drain loop, so that is not the issue. Around my area, many state licensed plumbers would make the connection of the Dishwasher drain into the "Garbage Disposal" (food waste disposal) in new construction and the inspectors passed it. What principle informs us that it should not be done that way? Has the code changed?


Why would you think the drain should not be connected to the disposal? Most common brand disposals come equipped from the factory with a inlet for a dishwasher drain line.

[John C Hansen, LEED AP]

Why would you think the drain should not be connected to the disposal? Most common brand disposals come equipped from the factory with a inlet for a dishwasher drain line.

Gene,

Thanks for asking. I saw this issue written up in a sample inspection report from an inspector working in my area. I have been reading many sample reports lately as a way to learn what style reports I want to do myself. I cannot find the report now to see who the inspector is or I would contact him directly. So I ask here in this forum.

[Gene South]

Gene,

Thanks for asking. I saw this issue written up in a sample inspection report from an inspector working in my area. I have been reading many sample reports lately as a way to learn what style reports I want to do myself. I cannot find the report now to see who the inspector is or I would contact him directly. So I ask here in this forum.

Provided it is done correctly, connecting a dishwasher drain is allowed and common, unless there is some specific local rule against it, at the local level.

[Scott Patterson]

Gene,

Thanks for asking. I saw this issue written up in a sample inspection report from an inspector working in my area. I have been reading many sample reports lately as a way to learn what style reports I want to do myself. I cannot find the report now to see who the inspector is or I would contact him directly. So I ask here in this forum.

I know of nothing that says it can't be done. I would say that inspector is misinformed. Now, if it is not allowed by the local AHJ that is another issue.

[Mark Reinmiller]

Learning by reading other inspectors reports is a bad way to learn. Many inspectors are full of bad information.

[John C Hansen, LEED AP]

Thanks to an experienced inspector here in Illinois who sent me the relevant code. It seems the Illinois plumbing code reads: "Dishwashers shall not discharge into food waste disposal units." This can be found here: Section 890 (http://www.ilga.gov/commission/jcar/admincode/077/077008900F07100R.html)
Thank you EB.

And Mark, I always do fact checking when I am unsure of something I read. Even some of the course material I have been reading was slightly different than my understanding of the real world. And, it seem the real world here in Illinois is not like it is in other parts of the country.

[Scott Patterson]

Thanks to an experienced inspector here in Illinois who sent me the relevant code. It seems the Illinois plumbing code reads: "Dishwashers shall not discharge into food waste disposal units." This can be found here: Section 890 (http://www.ilga.gov/commission/jcar/admincode/077/077008900F07100R.html)
Thank you EB.

And Mark, I always do fact checking when I am unsure of something I read. Even some of the course material I have been reading was slightly different than my understanding of the real world. And, it seem the real world here in Illinois is not like it is in other parts of the country.

Yep, Illinois is defiantly unique. Only state in the union with a wing at the state prison just for elected officials!

[Gunnar Alquist]

In California, a "high loop" is not an acceptable substitute for an airgap. Direct connection to the disposal is not allowed.

[Lon Henderson]

Around here, most if not all, muni's require a separate and dedicated drain to collect the dishwasher discharge.

[Garry Sorrells]

John,

This forum has a space for you to enter search criteria and there is quite a extensive range of topics that have been covered over the years. You may have to try different types of words and combinations to bring up links to threads, but it is well worth the effort to learn research methods. Especially since Illinois has some screwy code requirements not found elsewhere.

Here is some help with your researching techniques. I know you have stated you do not like to do research and would rather just ask questions, but learning will be of great benefit to you in the future.

Search : " Illinois dishwasher code "

The search will yield these threads. Though I did not find one that was from some time back that was on topic and very extensive that also had something to do with a law case and fine imposed. But I really did not look that hard.




http://www.inspectionnews.net/home_inspection/plumbing-system-home-inspection-and-commercial-inspection/8463-drainage-systems.html?highlight=illinois+dishwasher+code

In Illinois the dishwasher is not to be connected to the garbage disposal unit.

Section 890.770 Dishwashing Machines
a) Domestic Dishwasher (Private Residence). When a domestic dishwashing machine drain line is connected to the house side of a trap from a sink, the drain from the dishwasher shall be carried up to the underside of the spill rim of the sink. Dishwashing machines shall discharge separately into a trap or tail piece of the kitchen sink and shall not connect to the food waste disposal unit.
The way I plumbed in a single basin sink with a dishwasher and garbage disposal. Is two p-traps. The trap off the disposal is the easy one. The dishwasher one you need to make a fitting out or copper that increases from the discharge hose size to the size of the trap. I wish I took pictures to share with you.

Best thing to do is call your local plumbing inspector and ask him his preferred way of doing it. Every township I have done work in the different plumbing inspectors wanted it done their way, which still met the Illinois code.


Also:
http://www.inspectionnews.net/home_inspection/electrical-systems-home-inspection-and-commercial-inspection/8383-avoiding-physical-damage-fwg-food-disposer-cords-controls.html?highlight=illinois+dishwasher+code

and
http://www.inspectionnews.net/home_inspection/plumbing-system-home-inspection-and-commercial-inspection/8099-traps.html?highlight=illinois+dishwasher+code

[Eric Barker]

This is an example of being careful of blanket / across the board statements that say something is ok or not ok. "Your mileage may vary."

[Randy Ashcraft]

This is an example of being careful of blanket / across the board statements that say something is ok or not ok. "Your mileage may vary."

I recently serviced a clogged drain where the resident had ran the dishwasher to clean some dishes in the dishwasher because the sink drain wasn't working. The dishwasher drained into the disposal. This resulted in a flooded kitchen. This would of been avoided if there was a separate drain and maybe is the thinking behind some state codes. Unclogging the drain would have also avoided the flooding.

[Oscar Sparo]

What is the principle behind the statement that the dishwasher should not discharge into the disposal? Yes, there is a drain loop, so that is not the issue. Around my area, many state licensed plumbers would make the connection of the Dishwasher drain into the "Garbage Disposal" (food waste disposal) in new constructiion and the inspectors passed it. What principle informs us that it should not be done that way? Has the code changed?

My dishwasher doesnt work well, and I think it is because of how it is hitched up to the disposal. I'm not a plumber. I hired someone to install the dishwasher and disposal with accompanying plumbing. Here is what I think happens.

My dishwasher, within a cycle, recycles used water to rinse the dishes. If, before starting the dishwasher, the disposal is not completely clean and rinsed out, when the dishwasher runs it fills the disposal with water and some of the food that was left in the disposal gets pumped back into the dishwasher. So little tiny bits of food from the disposal get squirted on the dishes sometimes causing the dishes to come out dirtier than when they went in. The glasses are especially susceptible to this problem. If the disposal is run for a while, and rinsed with water, before running the dishwasher, this does not happen.

I have look at the hook-ups and cant see anything the plumber did wrong. But, if anyone finds the solution I would love to know because I sure hate doing dishes.