ha, haven’t done that in awhile. 
Will
What issues are there with using the plastic flex piping?
Not allowed in state code.
Sure, I know its a code issue, but knowing the code is important, isn’t it. If not, why do we study the NEC and get IRC certified and all.
If people are buying a house that has code violations, they are buying that liability.
In Illinois, state law requires that we call things out based upon “current construction standards”, which means national and state codes.
My second question, on this thread, is does anyone know why the code says this. There usually is a reason.
Besides, it’s a good indicator is the work was done professionally or not.
It traps grease and debris Will.
Here is the wordage.
TITLE 77: PUBLIC HEALTH
CHAPTER I: DEPARTMENT OF PUBLIC HEALTH
SUBCHAPTER r: WATER AND SEWAGE
PART 890 ILLINOIS PLUMBING CODE
SECTION 890.410 FIXTURE TRAPS/CONTINUOUS WASTE
**Section 890.410 Fixture Traps/Continuous Waste **
Type of Traps. Traps shall have a uniform and smooth interior, and shall have no partitions or movable parts. The trap seal shall be non-adjustable. (See Appendix D: Illustration C.)
Knowing that is probably more important than knowing the actual code. 
??Maybe too many people forgot to remove the plug before connecting the DW drain??? But not me, nope never did that! :—) :oops:
Local Code takes precedence over manufacturers instructions, yes?
And best practices trumps all for HIs!
Rich in regard to the dishwashers , that would be for the reason I gave earlier in that there is a possibility of cross contamination in that the disposal contains bacteria.
If the diswasher hose is not a reverse trap the water can go back into the dishes.
Could happen with conection to drain too.
Air-gap or high loop solves that.
I just looked at mine 10yr old home - DW drain to waste drain above trap.
If that clogs, the waste water is going into the dishwasher (if there’s no air gap/high loop)
yep you are right
Can you let my wife know?
According to her I haven’t been right for 10 years.
:humph: ](,) ](,) ](*,) :humph:
Actually, no. In most cases, the manufacturers requirements override local code. The common exception is when those requirements are in direct contradiction to local codes.
In other words, if there is any ambiguity, you follow the manufacturers requirements.
For example, California’s requirement is very clear;
CPC 807.4 No domestic dishwashing machine shall be directly connected to a drainage system or food waste disposer without the use of an approved dishwasher airgap fitting on the discharge side of the dishwashing machine. Listed airgaps shall be installed with the flood level (FL) marking at or above the flood level of the sink or drainboard, whichever is higher.
My cigarrette package says light and enjoy,but they still tell me I will get a ticket if I smoke. Go figure.
Thanks for the clarification.
I did notice in reading some dishwasher install instructions on line that for this particular question the manufacturer gives you an either / or option and defers to local codes.
Makes sense ,or they would not even have a knockout
I haven’t seen a new dishwasher in years that the drain line was not factory mounted up over the chasis and then back down …would this not satisfy the air gap need???
Nope. An air gap and a high loop are different, although they’re intended to perform similar functions.
In CA it’s clear. The air-gap must be a listed component and it must be installed above the flood level of the sink or basin.
High loops are not secured above the flood level, but rather, the highest point beneath the sink or cabinet, so there is still the potential for cross-contamination.
does that not seem a bit like splitting hairs Jeff?
I don’t believe so, no. One method eliminates the potential for cross-contamination, while the other method simply reduces the potential.
Notice the discoloration in the drain line in this picture. Even if there is a high-loop behind the washer, there is the potential for this “muck” to be drawn back into the dishwasher.
I guess i see what you mean , although i think that in that picture it is apparent that the over the top of the chassis loop was abandoned and the drain line was brought in from the bottom of the cabinet…thanks…jim
You are correct about the configuration, but the point is this - The high-loop is a closed system, or vacuum (if you will) where there is always the potential for cross-contamination. The air-gap eliminates the closed system, just as with the anti-siphon valves required on exterior spigots.
The only way for an air-gap to fail, is if it were to become submerged, which is why it’s required to be above the flood level of the sink.