The simplicity of the air gap not only makes for an elegantly effective device, it also means there are fewer opportunities for malfunction. But that isn’t to say things can’t go wrong:
- The most common issue with air gaps is a blockage somewhere along the line, usually due to bits of food and grease accumulating over some time. These kinds of blockages are most likely to be found in the hose between the air gap and drain/disposal (where there’s less pressure to move things along). When a blockage becomes large enough, water coming out of the dishwasher will begin to back up, spilling out of the air gap into the sink basin. Try disconnecting the hose and flushing it out.
- If a blockage can’t be found in the hoses, there could be something inside the air gap itself – a bottle or pipe brush may be handy in clearing out the unit. If that doesn’t solve the problem, it’s possible the blockage lies past the hoses: in the the disposal itself, or the trap(s) under the sink. While you would probably notice such a clog well before the dishwasher brought it to your attention, this would be the last obvious place to look. Remove the p-trap and clean out any blockages.
- Ensure that there are no kinks in the hose(s), and that no length is too long; there should be little slack when all is said and done. There should be just enough hose to get to the air gap inlet (or reach the highest point under the counter if using a high loop), and just enough to reach the drain or garbage disposal. The final run of the hose to the drain/disposal needs to be free of any sagging “traps” resulting from excess length, in which debris can accumulate and cause a blockage.
- If the dishwasher is connected to a garbage disposal and constantly spits water from the air gap during draining, it’s possible that the knockout plug on the disposal inlet was never knocked out. It happens! Disconnect the power supply, and use a screwdriver and hammer to punch it out. A pair of long-nose pliers will be helpful in fishing out the plastic plug from the disposal.
- Avoid using standard corrugated, plastic hoses – they’re easier to damage than high quality rubber hoses, and the ridges inside are perfect for accumulating debris, which can lead to a clogged line.