How to Install an Air Gap RO Faucet? Learn Here!
Written by: Gene Fitzgerald // Last Updated: Feb 9, 2023
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Air gap faucets are specialized faucets with built-in backflow protection to prevent a clogged drain from pushing dirty water back into a reverse osmosis system.
These faucets are frequently used with under sink RO systems; in fact, they’re even required by plumbing code in some regions.
Let’s take a closer look at how to install such an air gap RO faucet, so you can get yours set up in no time.
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Key Takeaways
The installation process for an air gap RO faucet is fairly straightforward and similar to installing a regular RO faucet. The major differences are 2 additional tubing connections required and a larger hole to mount the faucet:
- Start by drilling a hole in your sink or countertop if there is no spare one. The hole should be at least 1-1/4” in diameter.
- Mount the faucet and secure it from underneath.
- Connect the filtered water outlet of the reverse osmosis system to the threaded faucet connection.
- The ¼” brine line connects to the smaller input barb on the air gap faucet.
- Finally, connect the ⅜” drain line coming from the drain saddle to the larger barb.
How to Install an Air Gap RO Faucet
The process of installing an air gap RO faucet is similar to installing a standard RO faucet, but because the air gap faucet has 2 additional tubing connections the installation hole must be larger.
What You Need
- Power drill with carbide bits (for porcelain) or hole saw (for stainless steel)
- Center punch
- Adjustable wrench
- Screwdriver
The Ideal Faucet Location
Installing an RO faucet of any type is significantly easier if you’re able to repurpose an existing hole instead of drilling a new one.
Sinks often have a pre-existing hole for a soap dispenser or a sprayer which can be reused for mounting the faucet. Some sinks may also have a knock-out hole with a plug cover that can simply be removed and used for faucet mounting.
Further Reading:
If you don’t have one of the above, then you’ll need to drill a hole in your sink or countertop.
The ideal location will be flat, easy to access, and clear of the primary kitchen faucet and other connections.
1. Drilling
If your sink doesn’t have a pre-existing hole you can use, then you’ll need to drill one to accommodate the air gap RO faucet.
The process is somewhat different depending on the material you’ll be drilling through. In either case, you’ll want the finished hole to be at least 1-1/4” in diameter to fit all three input lines of the air gap faucet.
If the sink is stainless steel, then you won’t need to worry about cracking it, so you can start by using your center punch to mark the location of the hole. Then use a smaller ¼” bit to create a pilot hole. After the pilot hole is complete, use either a larger drill bit or a hole saw to widen the hole to your desired diameter.
If the sink is porcelain or enamel, you’ll need to be more careful to avoid cracking and marring the sink’s appearance. Use the drill at a low speed and be careful to move slowly through the drilling process. Again, you’ll want to start with a smaller ¼” pilot bit before swapping to a larger carbide bit as you widen out the hole to your desired diameter.
2. Mounting
Next up, you’ll want to mount the air gap faucet inside the hole.
Start by placing the rubber and metal washers on the base of the faucet. Then slide the entire assembly through the hole from the top and secure it on the other end using the lock washer and nut. Tighten the nut using a wrench to keep it locked in place (while being careful not to over-tighten).
3. Tubing Connections
Unlike a regular reverse osmosis faucet which only needs a single line for the filtered water, an air gap RO faucet needs three connections hooked up to it for it to work as intended.
The filtered water connection running from the post-filter outlet must be hooked up to the corresponding input on the faucet. Next, the ¼” wastewater line (sometimes called the brine water discharge) running from the RO membrane outlet must be connected to the smaller brine input barb on the faucet. Lastly, the ⅜” drain line from the drain saddle must be connected to the larger brine input barb on the faucet.
Once the tubing connections are hooked up, the faucet installation is complete! Test it out by running water through the faucet to ensure there are no leaks.
Air Gap RO Faucet Installation Tips
As mentioned previously, not all regions require the use of an air gap faucet when installing an RO system. If you find that your air gap faucet is excessively noisy, there is a method for transforming an air gap faucet into a regular one.
Remove the ¼” waste water line from base of the faucet and attach it directly to the drain saddle on the drain pipe (you may need to use an adapter). Then, remove the ⅜” drain line from the air gap faucet and discard it.
Keep in mind that some “gurgling” or “bubbling” noise is normal from an air gap faucet, and is not cause for concern. It’s up to you to decide if this is bothersome or not.
What Is an Air Gap Faucet and What Is Its Purpose?
An air gap reverse osmosis faucet is a specialized faucet with 3 connections rather than the 1 connection found on a regular faucet. Instead of wastewater flowing directly from the RO membrane to the drain saddle, it’s re-routed through the faucet to create an air gap.
Its purpose is to ensure that your RO system won’t pull wastewater into the unit in case the drain pipe becomes clogged. Instead of pulling wastewater into the RO unit, an air gap faucet ensures that only harmless air will be drawn in.
‘Air gaps’ have other plumbing uses, and are commonly used to prevent backflow to dishwashers and garbage disposals.
Air Gap Faucets vs Non-Air Gap Faucets
Both air gap and non-air gap RO faucets have their respective strengths and weaknesses, so it’s not a simple matter of air gap faucets always being superior.
The main advantage of air gap faucets is their ability to prevent the backflow of wastewater into the RO system. Additionally, they are required by plumbing code in many areas, so you may need one for your unit to comply with local regulations.
- When it comes to disadvantages, air gap faucets can be noisy and make a gurgling noise when the unit is in use.
- The air gap design means there is a small hole in the fixture, which wastewater will flow out of in case the drain line becomes clogged. This can make a mess on your countertop.
- Lastly, the installation process is more complex, and it requires a larger hole to be drilled in your sink.
Regular RO faucets are less expensive than their air gap counterparts and are easier to install. They are also less likely to become clogged than air gap faucets. The disadvantages of regular RO faucets are the risk of wastewater backflow into the system as well as they may not comply with local plumbing codes.
If you have any questions about how to install an air gap RO faucet please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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