A drinking water faucet is the small dedicated tap installed beside your main kitchen faucet to dispense filtered water, most often from an under-sink filter or reverse osmosis system. You need one whenever the treatment system produces water at a lower flow than the main line can deliver, or when you only want to treat the water you actually drink and cook with. Choosing one comes down to air gap or not, the hole in your sink, and finish.
Why filtered water gets its own tap
Under-sink filters and especially reverse osmosis systems produce water slowly and, in RO's case, from a small storage tank. Running that supply through the main faucet would drain the tank in moments and waste treated water on rinsing dishes. A dedicated drinking water faucet keeps the filtered supply for drinking, cooking, coffee and ice, while the main faucet keeps full flow for everything else. It also gives the filtered line its own clean path, so treated water never mixes back through the ordinary tap plumbing on its way to your glass.
Air gap versus non air gap
Reverse osmosis systems send reject water to the drain, and some plumbing codes require an air gap so drain water can never siphon back toward the membrane. An air gap faucet builds that break into its base: the drain line rises into the faucet body, crosses a physical gap, and falls back down to the drain. It is the code-safe choice but can gurgle and needs a wider mounting hole. A non air gap faucet is quieter and simpler, relying on a check valve for backflow protection instead. Which one you should fit depends on your local code, so it is worth a call before buying, not after drilling.
Mounting, finish and the practical details
Most sinks and countertops have a spare hole under a soap dispenser or sprayer blank that a drinking water faucet can occupy; otherwise a hole must be drilled, which is routine in stainless and laminate and a job for the right diamond bit in stone. Match the finish to your main faucet if the mismatch would bother you daily, since chrome, brushed nickel and matte black versions of most models exist. Look for a ceramic disc valve for longevity, a spout tall enough to fill bottles and pitchers, and lead-free certification on anything that touches drinking water.
If you cannot or do not want to drill: countertop options
Renters and anyone unwilling to modify a sink can get the same class of water from countertop systems, which stand beside the sink and dispense through their own spout. Vendors sell these as complete units, from simple carbon countertop filters to full countertop reverse osmosis machines with built-in dispensers, as Aquasana's countertop filter range shows. The trade is counter space and a visible appliance in exchange for zero plumbing changes. If you are weighing a faucet-mounted filter instead, our best faucet water filter comparison covers where those make sense and where they fall short.
Questions people ask about drinking water faucet
Can I connect a drinking water faucet to my fridge line too?
Yes, the filtered line can tee off to a refrigerator's ice and water supply, though with reverse osmosis you should confirm the fridge manufacturer allows the lower delivery pressure an RO tank provides.
Do I need a drinking water faucet with a simple carbon filter?
Not always. Many single-cartridge under-sink filters are plumbed inline to the cold side of the main faucet. The dedicated tap becomes worthwhile when flow is limited, cartridge life is precious, or you want untreated cold water still available.
Why does my air gap faucet make a gurgling noise?
That is drain water crossing the air gap inside the faucet body, loudest when the RO system is running its reject water to the drain. Some noise is normal; constant noise suggests a partly blocked drain line worth clearing.
Are drinking water faucets standard sizes?
Mounting shanks fit typical sink accessory holes, but air gap models need a larger hole than non air gap ones. Measure the existing hole and check the faucet's spec sheet before ordering rather than assuming any model will drop in.