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Martin Lehman

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Hi, I have 2 questions:

1) Can somebody please explain to me what the difference is between a DIRECT CONNECTION and and INDIRECT CONNECTION?

I dont get it.

What makes a connection to the waste system indirect and what makes a connection to the waset system a direct connection?

I have a feeling it has to with an air-gap, but I am not sure.

2) Now, what about an indirect receptor and a direct receptor?


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We have a lot af a/c condensate lines out here that are tapped into the lavatory drain pipe, upstream of the trap. Now, since there is no air-gap, this would be considered a direct connection right?

I have also seen a/c condensate lines that are connected directly into a dedicated trap. There is no air-gap and the trap has a primer to keep the seal. This is a direct connection and I call it out.

Is there really a difference between these two configurations? They are both connected to the drainage system WITHOUT AND AIR-GAP.

I get this from the Code Check books:

It says that the configuration of the condensate line to the lavatory drain is ok because it is an indirect receptor .

Well were the heck is the air-gap between the connection - There is none.

The same book also says that there are no direct connections to be made between the condensate line and drainage system.

Well isnt the configuration of the condensate line to the lavatory drain a direct connection since there is no air-gap?


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I'll quote Mike Casey's book, Residential Plumbing Inspection, directly:



The purpose of an indirect waste (air break or air gap) applied to any appurtenance or device used for the purpose of handling of prepared food, is to prevent the possibility of wastes backing up to a compartment where food is being stored or being processed and contaminating it.

The improper connection of equipment of this type would present a severe heath hazard and it behooves the installer to be well aware of the regulations governing such installations.

No evaporative cooler, air washer or similar air conditioning equipment and no cold storage room, refrigerator, cooling counter, compartment, receptacle, appurtenance or device which is used, designed or intended to be used for the storage or holding of food or drink shall have any drain pipe in connection therewith directly connected to any soil, waste or vent pipe.

All such equipment shall be drained by means of an indirect waste pipe. All wastes draining such equipment shall discharge through an air break into an open floor sink or other approved type receptor which is properly connected to the drainage system.

Exception: The foregoing does not apply to any dishwashing or culinary sink in any food preparation room, unless such receptacle is used for soaking or washing ready to serve food, or to walk-in refrigerators and combination walk-in, reach-in refrigerators used for storage and sales of products packaged in bottles, cartons or containers.


No plumbing fixtures served by indirect waste pipes or receiving the discharge thereof SHALL be installed until first approved by the Administrative Authority.

An indirect waste pipe is a pipe that does not connect directly with the drainage system but conveys liquid wastes by discharging into a plumbing fixture, interceptor or receptacle which is directly connected to the drainage system.

An Air Break is a physical separation which may be a low inlet into the indirect waste receptor from the fixture, appliance or device indirectly connected.

Elsewhere in the book he says:

  • No evaporative cooler or air conditioning condensate drain shall connect directly to soil, waste or vent pipe.
  • Indirect waste connections to the drainage system, oftentimes seen at a clothes washer drain, is permitted.
  • The airgap-drainage shall not be less than one-inch between the drain termination and the rim of the receptor. When permitted, the air break may terminate below the rim of the receptor, such as seen at a lavatory sink drain indirect connection (connection belongs at the fixture side of the trap).
  • Dishwasher should not be directly connected to the drainage system; an approved air-gap device should be used.
  • Dishwashers should not be connected to the waste side of a garbage disposal. One other common method of connecting dishwasher drain lines is the 'High Loop" method. Many jurisdictions have not required the air gap device, however, they still recognize the logic that should the sewer line become blocked and waste is backing up, you would not want t contaminate the dishwasher. By installing the drain line in a loop up under the sink as high as possible the waste will spill over the rim of the sink before it forces it's way into the dishwasher.
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When I built my laundromat I had to build an indirect waste system to accept the dirty water from the washing machines. This was to prevent the lint and more so to allow the suds from the machines to dissipate before going into the city system.

It consisted of a large tank to accept the water from the drains, the feed at the tank had to be about 12" higher than the sides of the tank (air gap). The drain in the tank was about 8" higher than the bottom of the tank to allow the sludge to settle and with screens around the opening to catch any floating lint.

2 or 3 times a year the tank had to be cleaned out. Messy job, but a real treasure hunt. Chains, rings, money and alot of c**p.

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