Thread: Air Gap, Air Break

This is another one that made me think hard to find an application where an Air Break is used.

We all know what an air gap is whether talking about distribution piping or a drainage system but can anyone think of an appliance that uses an air break?

Commercial applications are easy but anyone come across any in a residential application?

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Clothes washer standpipe.

From the 2006 IRC.
- SECTION P2718
- - CLOTHES WASHING MACHINE
- - - P2718.1 Waste connection. The discharge from a clothes washing machine shall be through an air break.

Added code reference with edit, I figured that would be the next question someone would have - documentation.

Originally Posted by Jerry Peck

Clothes washer standpipe.

I can see your point but how is that below the flood level rim?

Originally Posted by Jeff Remas

I can see your point but how is that below the flood level rim?

First this:


AIR BREAK (DRAINAGE SYSTEM). An arrangement in which a discharge pipe from a fixture, appliance or device drains indirectly into a receptor below the flood-level rim of the receptor, and above the trap seal.

Now to answer your question:

The clothes washer drain hose extends down into the standpipe (a receptor) such that the end of the drain hose is below the flood level rim of the standpipe (the receptor), but above the trap seal.

OK, I'll buy that explanation.

Same must go for a DW into the side of a disposal then huh? definitely below the flood rim right?

Might that be different, because the drain from the DW is directly attached to the disposal (or tailpiece), whereas the washing machine pipe is just hanging in there?

Unless I am misunderdstanding you the dishwashers have to be installed with an air gap/break device before going to the tail piece or disposal.

Originally Posted by Jeff Remas

Same must go for a DW into the side of a disposal then huh? definitely below the flood rim right?

Originally Posted by Joshua Hardesty

Might that be different, because the drain from the DW is directly attached to the disposal (or tailpiece), whereas the washing machine pipe is just hanging in there?

I agree with Joshua in that it "might be different" but for a different reason.

You are correct in that it connects in below the flood level rim of the receptor (the disposer and sink) and above the trap, but ...
- there is no air around the connection as there is on the clothes washer drain, that hose is not to be sealed to the standpipe, with the dishwasher it is sealed
- there is another source of water entering the disposer - from the sink, making that 'not an air break' at times, and, when the dishwasher is draining under pump pressure, the disposer is filling up to or above the connection point, unlike the clothes washer

The above also applies to the connection of a dishwasher to a sink tailpiece with no disposer.

What is it then? Not sure, good question.

However, for dishwashers, the IRC says this "P2717.1 Protection of water supply. The water supply for dishwashers shall be protected by an air gap or integral backflow preventer.", but it does not state that for clothes washers.

To me, that indicates an acknowledgment that there is a difference between the two connections.

I believe clothes washers have an integral air gap for the water distribution piping. There are air gaps required for both drainage and distribution piping and need to be thought of separately.