Dishwasher Drain Line

[Mark A. Simmons]

Okay, Any of you heard of a Dishwasher that does not need/require a Drain Line High Loop (Air Gap) A Realtor that i work with a lot told me that a Plummer friend of her that. Me Thinks she pullin My Chain..... Anyways..what have you guys heard/Know.....

[Charles Buell]

some of the newer dishwashers have built-in air gap devices---many jurisdictions still require----and the dishwasher installation manuals still require---- an air gap device

[Russel Ray]

I think it was Jerry Peck during his short membership period with us who posted an installation manual for a dishwasher brand that did not require an exterior air gap unless local codes required it.

[Michael R. Boyett]

The theory is that the input line to the dishwasher has an integral airgap or other x-connection prevention device built in already and that one on the output drain line does little to nothing to improve on that. In other words, even if water did siphon back to the dishwasher from the sink it would not constitute a cross connection to the potable water supply.

[Doug Edwards, CMI]

I just helped my sister by installing her new dishwasher in the home they are building. It has a built in high loop. In the rear corner of the unit the drain hose connects near the bottom onto a hard poly plastic tube that is formed into a long narrow loop (shaped similar to a hair pin) that loops almost to the top then returns to bottom corner where it started, where the flex hose is then attached that routes it over to the sink drain or the garbage disposal. It is completely built in, rigid plastic and as far as I could tell is probably a better set up than the typical high loop you see under sinks. It has a much more pronounced loop requiring water to literally run up hill. I told her to take a picture before the County inspector got there because once it was enclosed in the counter they would not believe her that it had a built in loop. I will see if she actually did what I told her and if so I will post the photo here. Don't hold your breath though.

[Dale Duffy]

Many commercial installations have back-flow preventer's on the drainline.

[Brian E. Kelly]

Yes all new dishwashers have a back flow preventer.

[Mark A. Simmons]

Thanks for all the info Guy's, time to get back at it......

[Russel Ray]

Considering how easy it is to install an external backflow prevention device, I prefer the redundancy that it offers. I really want to be sure that those dishes are clean when I pull them out of the dishwasher.

I rarely see a high loop that is installed properly and prefer the sinktop air gap to air loops, and warn my Clients that the high loop can be pulled down very easily by kids getting into the sink cabinets, as well as simply from everyday use in sticking things in the cabinet and pulling them out.

[Keith Swift, PhD.]

Yes, a built-in anti-siphon, but what about the potential for bacterial contamination without an air-gap. I don't pretend to know the answer, but I won't bless a dishwasher (new or old) without an air-gap. However, I'd be interested in knowing the "truth."