water coming out of dishwasher air gap

[Stephen Tashiro]

At a friend's house, water comes out of the dishwasher air gap on the sink when the dishwasher drains. There are no clogs in the drain line from the air gap to the garbage disposal. The line is not kinked. The air gap itself is not clogged. The input hole to the dishwasher is not clogged. (We took the air gap and the drain line off and made sure they were clear before re-installing them.) Is it possible that the dishwasher just drains too fast for the air gap system? Do dishwashers typically have an adjustment that sets how fast they drain?

[Lee Schierer]

Can you post a photo of the plumbing under the sink that shows the dishwasher connections? Also, please explain what you mean by "air gap". This link shows some common errors (https://structuretech.com/dishwasher-drains/) made with dishwasher plumbing.

[Tom M King]

Probably a problem with the drain line past the trap. Something is causing it to drain too slowly.

I expect you're talking about an automatic vent. That is not the problem, unless it was installed too low. Water should drain fast enough to flow away before it can rise that high.

[Myk Rian]

Is there a disposal installed? They can cause a blocked pipe due to grease. Take the P pipe off and check.

[Stephen Tashiro]

Also, please explain what you mean by "air gap". This link shows some common errors (https://structuretech.com/dishwasher-drains/) made with dishwasher plumbing.

DIshwasher air gap: https://www.tampaapplianceparts.com/blog/what-is-a-dishwasher-air-gap/

( The link you gave has a section about dishwasher air gaps.)

[Stephen Tashiro]

Is there a disposal installed? They can cause a blocked pipe due to grease. Take the P pipe off and check.

Yes there is a garbage disposal and the drain line from the air gap goes into the disposal. I can look into the disposal while the dishwasher is draining and see water enter the disposal. Water does not build up in the disposal.

[Paul F Franklin]

Disconnect the line from the air gap to the disposal and let it drain into a 5 gallon bucket. Run a cycle and see if the problem recurs. That will tell you if the problem is ahead of the disposal or after. This problem is almost always clog related. Most air gaps have a smaller inlet and a larger outlet. Make sure the DW isn't connected to the outlet side. And make sure you don't have the drain stopper in place on the sink drain when you run the DW; that can slow draining enough to cause the problem.

If all else fails, see if an air gap is really required by code in your area. A lot of areas just require the drain hose to be run up high under the cabinet and then down to the disposal. Maybe you can just do away the air gap.

[Thomas McCurnin]

So there should be two hoses going into the air gap cap. There are specially made little brushes to clear out any clog, either on the dishwasher side or the disposal side. A clog on either side will cause the gap to leak. This is going to sound disgusting but I just spray the gap cap (with the cover off) with some bleach solution, let it sit for a couple of minutes, rinse it off and dry it, then put my lips to the gap cap and blow to clear the line. Works every time.

[Rick Potter]

I bought a house recently and had the same problem. Turned out that no one removed the dishwasher plug in the side of the disposal when they installed it.....at least 10 years prior.

[Kev Williams]

someone help me understand:

469066

[Rod Sheridan]

It doesn't, the purpose of the airgap is to prevent you from pressurising the drain system.......Regards, Rod.

[Mark Bolton]

Just ditch the air gap. They are an old tech, modern diswhashers can push far more than most airgaps were ever designed for. A through counter air gap is like 1970 era. If your seeing water out of the air gap and not coming up through the disposal its either drain hose size or the airgap just cant handle the output of a modern dishwasher. Dumping into a disposal all your post flow is going to be gravity through the disposal and down the drain so if there is a real issue and your DW drain hose is not plugged/too small, youd be seeing DW discharge in the basin with the disposal.

Rip the airgap out and plug the hole.

[Mike Soaper]

clearing the air gap itself starts at about the 1:20 mark

Air Gap Leaking Water? Easy Fix Guaranteed! - Bing video (https://www.bing.com/videos/search?q=Air+Gap+Plumbing&&view=detail&mid=CE7C776486224275FF99CE7C776486224275FF99&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3DAir%2BGap%2BPlumbing%2 6FORM%3DVARSQP)

my take on why an air gap is recommeded is to stop potential back siphoning from the sink\disposal\waste line

[Tyler Bancroft]

Just ditch the air gap. They are an old tech, modern diswhashers can push far more than most airgaps were ever designed for. A through counter air gap is like 1970 era. If your seeing water out of the air gap and not coming up through the disposal its either drain hose size or the airgap just cant handle the output of a modern dishwasher. Dumping into a disposal all your post flow is going to be gravity through the disposal and down the drain so if there is a real issue and your DW drain hose is not plugged/too small, youd be seeing DW discharge in the basin with the disposal.

Rip the airgap out and plug the hole.

Assuming their local code doesn't require an air gap.

[Stephen Tashiro]

someone help me understand:

469066

The air gap won't prevent the water you highlighted from flowing back into the dishwasher. It's purpose is to prevent water than's in the sink trap (or garbage disposal) from siphoning back into the dishwasher.

[Kev Williams]

You don't need an air gap for that, you only need a high-loop in the drain line. If the worst case scenarios are water spraying out of the air gap when it fails or some dirty water finding its way back into the dishwasher past the loop, I'll do without an air gap, thanks. :)

If draining into a disposal, it's nearly impossible to pressurize the dishwasher's drain line- for that to happen the main drain line would have to be totally plugged, the sink drain tightly plugged, and the disposal would have to completely fill with water from the dishwasher. Most people (that I know of at least) with disposals don't cap them in normal use, and a typical sink will hold more water than the water used in a full dishwashing cycle.

[Stan Calow]

Don't some local plumbing codes still require an air gap?

[Mark Bolton]

Assuming their local code doesn't require an air gap.

There is no local code out there that requires a through counter air gap with the potential to puke onto your counter. Its ancient tech.

[Paul F Franklin]

Not to be argumentative, but ancient tech or not, there are states and areas that require them. California (of course), Washington, Minnesota, and Hawaii are commonly noted as having this requirement, but I couldn't find a comprehensive list. Granted, everyone hates them, and they've been around a long time, but when properly installed and maintained they work. Plumbing traps are ancient tech too, but that doesn't mean they aren't needed or don't work. This is why I said in my original post "see if an air gap is really required by code in your area".

[Lee DeRaud]

I find the idea that the "ancient tech" air gap can't handle the pump output of a modern dishwasher to be a bit silly:
the newer dishwashers don't empty noticeably faster than the older ones, and they're pumping out a whole lot less water.

[Mark Bolton]

I find the idea that the "ancient tech" air gap can't handle the pump output of a modern dishwasher to be a bit silly:
the newer dishwashers don't empty noticeably faster than the older ones, and they're pumping out a whole lot less water.

I think what you will commonly find is that the air gap is very often confused with protecting the water supply and the drain most commonly by home inspectors and not building/code inspectors. The high loop (which are now almost always doubly covered in most dishwashers because the manufacturers are integrating a high loop on the side/back of the appliance from the factory due to home center sales of appliances and homeowner/handyman installation) is the standard.

"P2717.2 Sink and dishwasher - Dishwashing machines may connect directly to the drainage system and do not require an indirect connection by drainage air gap or air break"

"P2717.3 Sink, dishwasher and food grinder. The combined discharge from a sink, dishwasher, and waste grinder is permitted to discharge through a single 11/2 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."

Virtually no one is installing through counter/above the counter air gaps for a dishwasher. No one.