Air gap or high loop

How many of you report on the lack of an AIR GAP or high loop on a dishwasher?


Always. Which is almost always around here.

Yes, and include a line drawing of how it should look.

I have never seen an AIR GAP installed at the sink, in the Kansas City, high loops, yes.

Neither have I Buck, I just check for the high loop. :slight_smile:

Does most of the NEW dishwashers have a built in high loop?

Same here.

I’ve been calling these out on a regular basis for obvious reasons plus IL. plumbing code requires it. No I do not quote code. Today I was reading an installation manual for a Whirlpool DW from a home I inspected yesterday and it states this;

[FONT=Arial][size=2]The drain hose must connect to the[/size][/FONT]
[size=2][FONT=Arial]house plumblng at a mlnlmum of[/FONT][/size]
[size=2][FONT=Arial]20 Inches (50.8 cm) above the
floor. Thls will prevent backflow or
water slphonlng out of dlshwasher
durlng operatlon.
If the draln hose Is routed to a
connectlon point less than 20
Inches (50.8 cm) above the floor,
the draln hose must form a loop
20 Inches (50.8 cm) above the
rloor. An alr gap must be used In
the hlgh draln loop.

If installed correctly above a trap most are installed above 20 inches therefore according to this would not require a high loop.

What you think?

I don’t because I don’t know how to tell whether the dishwasher has a built in high loop.

Even if it has a high-loop, I will call out a missing air-gap fitting.

Jeff, any particular reason for that call? I have never seen one yet in any home and it is called for in the plumbing code. Dosen’t seem to excite the AhJ’s very much.:slight_smile:

Not sure about code but most manufacture’s installation instructions call for a high loop or air-gap fitting.

Manufacturers instructions take precedence over code except when there is a “prohibition” in the code.

CA is very specific. If it’s connected to a disposer, it must have an air-gap.

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.

Thanks, now I got to dig up my own instructions for my dishwasher out of curiosity. :):wink:

The way I’m reading the manufactures instruction in my previous post is if the drain line is connected a min. 20" at the house plumbing that is sufficient in preventing backflow or water siphoning.

If there is a drain high loop, then there must be an air gap.

Here is the language I am presently using .

• The dishwasher needs to have the hose mounted above the basin in
order to help prevent water from backing up into the container
• . Air gaps are now standard equipment to assure a separation between
supply and waste water. It is advised that either an air gap or a high loop
be installed between the dishwasher and the waste connection.

Many of my comments are hybrids of everything I have learned right here over the past several years. (my how time fly’s)

I can only remember seeing maybe three or four air gaps in both Johnson County KS and KCMO in the last 40 years Buck.
Fixed a lot of dish washer drains that didn’t have a high loop either.

Glad you fixed them :slight_smile:


I call out the need for a High Loop also. And yes most newer style ones have built in High loops if they didn’t rework the hose. I still call them out.