What is the typical application of drinking water filter faucets?
Air Gap & Non-Air Gap drinking water filter faucets are utilized with RO, UF (ultra-filtration), single-stage (a sediment filter or a carbon filter), and dual-stage (sediment with a carbon filter) water filter systems. Air Gap faucets are typically used with RO systems only, as other filtration systems do not need the air gap. Drinking water filter faucets are separate from the main kitchen faucet and are attached to the cold water supply line. They can only be used with cold water.
Does the air gap have to be used?
No. Use of the air gap is optional. However, if you have an RO system, using the air gap is highly recommended as many local plumbing codes require it in the U.S.
What is the difference between air gap and non-air gap faucets?
Non-air gap faucets only have a filtered water line. Air gap faucets have three lines consisting of the filtered water line (permeate water) and the incoming and outgoing wastewater lines. An “air gap” is a siphon break to ensure wastewater cannot flow backward from the household drain system into the RO system. The incoming wastewater line sends wastewater to a non-pressurized trough at the bottom of the faucet before it goes to the drain. The drain hole in the back of the faucet is an escape hole so that wastewater can have a way out if the drain becomes clogged. This protects the RO system and the filtered water it produces from contamination.
What type of water filters require an air gap?
Only RO systems require an air gap because RO membranes produce wastewater, often referred to as “brine water.” Other under sink filters, such as carbon, sediment cartridges, and UF (ultra-filtration) do not produce wastewater.
What type of water filters can use non-air gap faucets?
Non-RO under-sink water filters.
What is the air gap? What does it do?
The air gap is a non-pressurized trough found at the bottom of the faucet. Wastewater from the RO system travels up to this gap and then down to the drain. The air gap trough acts as backflow prevention, so if the line became clogged for any reason, a small amount of air would flow back into the system instead of dirty wastewater, protecting the system and the filtered water it produces from contamination.
I just installed the faucet and it leaks out of the air gap vent hole. Is it defective?
The air gap vent hole on the faucet may have a very small bubbling leak of a few drops periodically for a week or so after the initial installation or filter replacements. This small leak is normal and is caused by air bubbles being forced the through filters and water lines.
The faucet air gap is noisy. Is it defective?
If you are using the faucet with a reverse osmosis system, you may hear noise coming from the RO system as it fills up the storage tank with water. You may also hear a slight draining or bubbling sound from the air gap when the RO wastewater drains. Both are normal, and are not a sign of any problem with your faucet.
My air-gap is constantly making a lot of noise. Is that normal?
Air gap faucets may make a small amount of noise while the tank fills, but it should not be very loud. If it is making a lot of noise, then the problem could be that your flow restrictor bypass valve is turned on. If it is turned on, then the flow restrictor is bypassed and, as a result, nearly all of the water going through the system will be sent down the drain as wastewater. The flow restrictor bypass valve needs to be set to the “OFF” position so that the flow restrictor is in use. Turn the gray toggle switch so that the prong is pointing out, away from the system, to the “OFF” position. This will engage the flow restrictor and limit the amount of wastewater sent to the drain, which should stop the loud noise you are hearing.
