Air gap faucets have a reputation for gurgling and for occasionally spitting water onto the worktop, and both complaints usually have the same cause in a place people do not look: the gravity drain line running from the faucet down to the waste connection. That line does not flow under pressure, so it is unforgiving of anything in its way.
Normal noise against a warning
A gurgling sound while the system produces is normal: water is crossing an open break inside the faucet body and it is audible. What is not normal is a change, particularly a louder or more strained sound, or gurgling that continues long after production should have stopped. The first suggests the drain path below is beginning to restrict, and the second suggests the system is not shutting off properly, which is a different fault involving the shut off valve rather than the faucet.
Spitting means the drain path is blocked
Water appearing at the gap or on the worktop means the water crossing the break cannot get away fast enough, so it backs up and escapes. The causes are all downstream: debris in the drain saddle, a sagging or dipped section of tubing, a kink behind the cabinet, or a saddle whose hole was never properly aligned with the hole in the waste pipe. Clear the line before suspecting the faucet, which is almost never at fault when this happens.
Clearing it
Disconnect the larger tube where it meets the drain saddle and check whether water then flows freely from the faucet, which tells you immediately whether the restriction is in the tube or at the saddle. Flush the tube through, and inspect the saddle's opening, which collects debris from the waste pipe over time. Then re-route the tube so it runs continuously downhill with no dips or long horizontal stretches, and secure it so it cannot sag behind the cabinet in future.
Preventing it
Keep the run short and steep. Use the tubing diameter the faucet specifies rather than a smaller one, since this line flows by gravity and diameter matters more than it would under pressure. Connect above the trap, never below it, so the water seal keeps sewer gas out. And if the system produces far more than it used to before shutting off, look at the automatic shut off valve, which fails without an obvious symptom. Our faucet filter guide covers the fixture options.
Questions people ask about air gap faucet
Is gurgling from an air gap faucet normal?
Yes, while the system produces. A louder or strained sound, or gurgling long after production should stop, is not.
Why is water spitting onto the counter?
The gravity drain line below the faucet is restricted: debris at the saddle, a sag, a kink or a misaligned saddle opening.
How do I find the restriction?
Disconnect the larger tube at the drain saddle and see whether water then flows freely, which isolates the tube from the saddle.
How do I stop it recurring?
Route the tube short, steep and continuously downhill in the specified diameter, and secure it so it cannot sag.