Who knows what an air gap faucet is by way of a show of hands? Is anyone familiar with the term “reverse osmosis”?
You’ll learn new terms for air gap faucets in this piece, and you’ll be better prepared to talk to your plumber about them or to examine plumbing codes that deal with them.
Air gap faucets have air gaps built into the base of the faucet to allow water to flow through. When you turn on an air gap faucet’s water, you’ll get the same amount of water as if it weren’t for the gap.
Let’s dive into the nitty-gritty, though, so that we can obtain a clearer picture.
Purpose of an Air Gap Faucet
Drainage water is directed upwards by the air gap system through a 1/4 inch pipe “A small trough placed into the base of the faucet is connected to a flexible tube. There is a non-pressurized trough on the other side of the faucet stem from which the water flows and falls into a 3/8″ hole” It is sent to the sink drain via a flexible tube.
Therefore, instead of having a single tube for drain water, the air gap faucet must have three tubes for drain water as well as a fourth tube to serve as the unit’s drinkable product water. As a result, the air gap faucet requires a larger sinkhole and a broader base.
With an air gap faucet, water naturally flows down the sink’s drain since the RO membrane’s drain line is supplied into a non-pressurized trough. However, a non-air gap faucet directs the RO membrane’s drainage into the kitchen sink’s garbage disposal. An air gap faucet simply connects to water.
Since it was originally designed to prevent filthy water from returning to the RO unit during an RO discharge line blockage, an air gap can be used to keep a small amount of air from entering the system.
How Air Gap Faucets Work
Reverse osmosis systems installed under the sink are equipped with air gap faucets. Filters don’t require an air gap, hence these are never employed.
Besides delivering drinking water from the RO unit, the air gap faucet serves as a “air gap” for the drain system of the RO unit.
The reverse osmosis system needs an “air gap” to prevent drain water from flowing backwards into the system.
The diameters of the tubes can be seen in the image above. There are two sizes of tubes: 1/4″ and 3/8″.
When the handle of the faucet is pressed, the “permeate” or purified water flows out of the long spout and into the user’s hands. In addition to this, there are two other hoses that are part of the drainage system.
Wastewater is generated by reverse osmosis units when they are in use. The waste water is dumped into a small open trough inside the base of the faucet through the middle tube shown in the picture. Drainage water travels down the open trough until it reaches the larger tube on the right, where it falls through a hole. The under-sink drain pipe is connected to the huge tube. By gravity, the huge tube descends and enters the under sink drain pipe.
An Airgap Faucet Installation Guide
Even though each faucet is unique, the general guidelines presented here should work for the majority of them.
Is There a Place for Water to Escape?
There aren’t any plans to do so at this time.
A blockage in the tube leading from the air gap to the drain pipe under the sink is frequently to blame when an air gap leaks. Cleaning the air gap may be necessary for treatment. It’s also possible that the drain line under the sink is clogged and needs to be cleaned. Consider running your garbage disposal for a few minutes to see if it’s causing leaks due to inactivity.
It’s not typical for water to be leaking out of the air gap. As part of your troubleshooting procedure, make a note of these potential trouble places and take the necessary steps to address them.
Cleaning An Air Gap Can Be Difficult.

You might be wondering how to properly clean an air gap. The air gap can become clogged with debris, resulting in leaking. There is an air gap brush tool for this purpose.
As long as you can see anything in the air gap, you should be able to remove anything with your fingertips after taking the cap off for a closer look. However, if you are unable to do so, a cleaning brush designed for this purpose would suffice.
At a plumbing supply store, one of the major DIY stores, and online you can get an air gap cleaning brush tool Brushes for cleaning air gaps are similar to infant bottle cleaning brushes, except they are much thinner and longer, up to two feet long.
Does Your Kitchen Faucet Need an Air Gap?
If you’re installing a RO system, you’ll almost certainly need an air gap. It is a vital component because of its role in the RO drainage process and its ability to avoid contamination of the already-filtered water.
Typically, RO systems employ a faucet that has an air gap built-in, and manufacturers prefer to use a faucet that already has an air gap built-in.
There is a RO system in the water supply, so the answer is yes; an air gap is required for your kitchen faucet if it is under the sink. If your local plumbing code does not demand it, it is essential to have a clean and pure filtration system that ensures that water flows in the appropriate direction.
Advantages of the Air Gap RO Faucet
- The actual line break in an air-gap system prevents water from being sucked back into the RO system in the event of a blocked sink drain.
- Using a RO system and an Air Gap faucet is required by many local plumbing codes.
Disadvantages of a RO Air Gap Faucet
- Because of the air barrier created by water dropping into the trough, Air Gap faucets might make a gurgling sound while filling the tank.
- When silt clogs small tubes and troughs on the air gap system, water can back up into sinks or countertops.
- The installation is complicated because of the additional tubing and connectors.
- Because an air-gap system needs to be connected to a sink drain, it cannot be installed without a faucet.
What causes Air Gap Faucets to make a humming sound?
Although the “concentrate” or wastewater may make a “gurgling” sound as it passes through the membrane and into the drain, Reverse Osmosis systems are normally fairly quiet. The polluted concentration is flushed out of the system by “crossflow” water. The flushing prevents the unit from becoming clogged.
An air gap system can make gurgling noises when filling the storage tank, so be aware of this if you have one. The water in the faucet slowly drains into the drain line as the tank fills. The “air gap” trough collects this water, which eventually drains into the sink. When water is slowly trickling, it frequently makes a gurgling noise.
Any “hissing” noises you hear should be reported to your local water treatment professional right away in that they could point to a leak, air gap, or a problem with the water pressure.