Any Illinois plumbing code gurus out there?

I was recently told by another inspector that in Illinois the dishwasher drain cannot be installed on the drainage port built into the side of a garbage disposal. I have to admit I have never heard this before.

I even did a search through NACHI’s education to see if it was mentioned anywhere but I came up empty. True, untrue, Illinois specific, true everywhere?

He was right.
Ignore the out of state answers following.
You are also required to have an air gap but it is never enforced.

Disposal is considered like a pump that can force bacteria infested water towards the dishwasher.

Simply recommend they put it on a tee connection and keep the hose tied up very high as possible.

He is correct.

http://www.ilga.gov/commission/jcar/admincode/077/07700890sections.html

There it is, Thanks Bob and Chris! I knew about an air gap, but I didn’t realize the disposal was outlawed. That’s odd to me. Oh well, time to rewrite a some report comments.

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.

If you read the code you posted it states the drain discharge needs to be a high loop to the tailpeice. It does not say anything about an airgap being required.

TITLE 77: PUBLIC HEALTH
CHAPTER I: DEPARTMENT OF PUBLIC HEALTH
SUBCHAPTER r: WATER AND SEWAGE
PART 890 ILLINOIS PLUMBING CODE
SECTION 890.770 DISHWASHING MACHINES

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.

Doesn’t the “high loop” create the air-gap?

No. A “high-loop” is a method of installation that allows a downhill slope in the drain line to its point of connection to the waste system. A high loop can still siphon waste-water back into the dishwasher.

An air gap is a physical break in the drain line that will not allow waste water back into the dishwasher.

An air-gap “device” is a pre-manufactured component with the break built into it. CA requires an “air-gap device” or fitting as opposed to an assembled air gap.

801.0 All indirect waste piping shall discharge into the building drainage system through an airgap or airbreak as set forth in this code. Where a drainage air gap is required by this code, the minimum vertical distance as measured from the lowest point of the indirect waste pipe or the fixture outlet to the flood-level rim of the receptor shall not be less than 1 inch.

indirect waste drainage prevents sewage from backing up into a special fixture and contaminating its contents in case there is a stoppage in the sanitary drainage system.

Fixtures or appliances with indirect waste pipes, that are not connected directly to the drainage system would be an ice machine, bar sink, hand sink, refrigerator, cooler or refrigerant could, steam tables, dishwashers, water stations, and similar fixtures.

The indirect waste pipe would drain into a sink, floor sink, a drain pipe, or approved fixture.

All indirect waste receptors must have adequate capacity and a design that prevents splashing.

Any required vent must extend to the outside air and never connect to the same vent that is connected to the sanitary sewer.

Restrictions apply as the maximum length of indirect waste piping in hand sinks, bar sinks, and similar fixtures.

Bob, you are correct. Air gaps are best, but high loops are allowed in Chicago. All about back flow.

I really wish someone would let the ABT and Grand appliance installation guts know about this. I see dishwahers connected to disposers about 50% of the time.

The agents and lawyers are REALLY getting PO’d when I call this out. Easy to fix, but I see it all the time in new construction.

Read the topic in the first post, this section of the standards was posted as it related to the topic, not the air gap.

Thanks Bob for the other section on the air gap, that’s good info to know.

Actually I believe it is one of those codes that does not get enforced Will.If you have a copy handy of the Chicago code that addresses the subject would love to see it as I might have saved a copy of the code showing it as required.
Not a code Inspector however and only use it as a guide on my opinion but here is my report commentary and feel free to use it as well as anyone else.

Airgaps are now standard equipment to assure a separation between
supply and waste water. It is advised that either an airgap or a high loop
be installed between the dishwasher and the waste connection

Not sure if I wrote it or someone else offhand.

No problem.
Having spent time at many different type jobs ,did 6 years as a head appliance installer for Sears.

Would feel silly not focusing a little more on the subject.

I’ve seen that quote before also. But as Jeff P wrote an 'airgap and 'high loop perform separate functions.

So recommending either, or, would not be correct?

Water seeks its own level and my concern is water not be drawn in through gravity as disposal hookups are not allowed anyway.
Wish there was a list of which dishwashers have an integral air gap built in.

Please explain how a siphon effect might occur with a high loop installed.
Siphon effect would also empty the trap ,would it not ?

Dishwashers are not equipped with built-in air gaps. There are, however, several models that have built-in check valves.

Have you never siphoned gasoline from a vehicle tank? The same physical principle applies.

Not necessarily.

If the sink-trap is clogged and the sink filled to the top, what is to prevent water from back-flowing through a high-loop? Nothing.

Under these same conditions, an air-gap serves as a break that will not allow waste water back into the dishwasher drain line. Instead, it will spill over at the air-gap, wherever it has been installed.

Check valve/air gap same result.
A siphon could only occur if hose is below the basin water level.
Most of the double basin sinks we see today have a low divider in between.

No doubt a air gap is better but a high loop will do a good job (must go all the way up) and makes an easy correction.
Nobody has gone out and drilled a hole in the new Granite counter top based on a report.
California is not Illinois by the way Jeff.

Go out and look at Plumber forums to see the same opinions as mine.

The only issue with air gaps is all the sputtering that sometimes creeps up.

I am more concerned with them not mounting the units in some ways as that can cause the copper line to leak.

We also do not allow plastic flex here Jeff .