Thread: Air Gap for dishwasher required?

In Washington state is a air gap for a dishwasher required?

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P2717.1 Protection of water supply. The water supply for
dishwashers shall be protected by an air gap or integral
backflow preventer.

Lisa in the OP, did not state if she is asking about the air gap for the supply side, or tn air gap for the drain side. However since the supply side is fixed by the manufacturer and cannot be changed I think she is asking about the drain side.
The 2006 IRC does not require an air gap on the drain side. But she is wanting to know if Washington state has a requirement for an Air gap on the drain side.
I cannot answer that question.

FWIW
A little information on DW's
The IRC requires the SUPPLY side to be protected by either an air gap, or an integral backflow preventer.
AFAIK all modern DW are protected by an air gap for the supply.
The water supply connects to the solenoid, runs up the side of the tub above the threshold of the door, and empties into the tub. This meets the requirement for an air gap.
I do not know of any current DW that uses a backflow preventer on the supply.
Note: I said I do not know, not there is not one.

The IRC does not require an Air Gap on the drain side. However some States and local AHJ's may require an air gap on the drain side.

An Air Gap on the drain side is not built into the DW, ever.
Some DW's do have a "High Loop" built into the design.
If the DW has the high loop built in it can only be confirmed by removing the DW. Even if the DW does have the high loop built in, the IRC requires the drain line to be securely fastened to the underside of the counter.
This requirement eliminates any confusion as to if the DW has a built in high loop or not. The drain line must be fastened to the underside of the counter.

2006 IRC

P2717.1 Protection of water supply.

The water supply for

dishwashers shall be protected by an air gap or integral

backflow preventer.

P2717.2 Sink and dishwasher.

A sink and dishwasher are permitted

to discharge through a single 1

1/2-inch (38 mm) trap.

The discharge pipe from the dishwasher shall be increased to a

minimum of

3/4 inch (19 mm) in diameter and shall be connected

with a wye fitting to the sink tailpiece. The dishwasher

waste line shall rise and be securely fastened to the underside of
the counter before connecting to the sink tailpiece.

P2717.3 Sink, dishwasher and food grinder.

The combined

discharge from a sink, dishwasher, and waste grinder is permitted

to discharge through a single 1

1/2 inch (38 mm) trap. The

discharge pipe from the dishwasher shall be increased to a minimum

of

3/4 inch (19 mm) in diameter and shall connect with a

wye fitting between the discharge of the food-waste grinder

and the trap inlet or to the head of the food grinder. The dishwasher
waste line shall rise and be securely fastened to the
underside of the counter before connecting to the sink tail piece

or the food grinder.