What you need to know before you start
A single handle kitchen faucet can be replaced in about an hour with basic tools you likely already own. The job involves turning off the water supply under the sink, disconnecting the old faucet, and bolting the new one in place. You do not need a plumber for this—the hardest part is usually reaching the bolts underneath the sink, not the plumbing itself.
Before you buy a replacement, check what kind of sink you have. A standard kitchen sink has either one hole (for the faucet spout only) or three holes (spout, hot handle, cold handle). Single handle faucets come in both styles. Measure the distance between the outer edges of your sink holes—this is called the "spread"—and bring that number when you shop. Most single handle faucets fit 4-inch or 8-inch spreads.
Key Takeaways
- Turn off the water supply at the shutoff valves under the sink before disconnecting anything, and test that the water is actually off by turning on the faucet.
- The old faucet is held down by bolts underneath the sink; you will need a wrench or basin wrench to reach and remove them, and a bucket to catch water still in the lines.
- New faucets come with mounting hardware and instructions specific to that model, so read them before you start—the order of washers and nuts matters.
- After the new faucet is installed and tightened, turn the water back on slowly and check for leaks at every connection before you consider the job done.
Turning off the water and preparing the space
Look under your sink. You should see two small valves on the water lines coming up from the wall or floor—one for hot water, one for cold. Turn both valves clockwise until they stop. They should turn by hand; if they are stuck, spray them with penetrating oil and wait a few minutes.
Once the valves are closed, turn on the kitchen faucet at the sink. Water should stop flowing within a few seconds. If it still runs, the shutoff valves are not working properly and you need to find the main water shutoff for your house before you proceed. The main shutoff is usually in the basement, crawlspace, or outside near the foundation.
Place a bucket under the water lines. Even with the shutoff valves closed, there is still water trapped in the lines between the valve and the faucet. When you disconnect the old faucet, this water will drip out.
Removing the old faucet
Look at the base of your faucet where it comes through the sink. You may see a decorative collar or cap. If it unscrews by hand, remove it. If it is glued on, leave it—you will work around it.
Reach under the sink and locate the bolts holding the faucet down. On most faucets, there are two bolts, one on each side of the spout. A basin wrench is the right tool for this job because it has a long handle and a head that fits into tight spaces. If you do not have one, a regular adjustable wrench works, but you will have less room to turn it. Loosen both bolts by turning them counterclockwise. Once they are loose enough, you can usually finish unscrewing them by hand.
Disconnect the water supply lines. These are the flexible hoses or rigid tubes running from the shutoff valves to the faucet. Most modern faucets use compression fittings—a nut that screws onto a threaded fitting. Turn these nuts counterclockwise with an adjustable wrench. Have your bucket ready; water will come out. Once the lines are disconnected, lift the old faucet out of the sink.
Clean the sink surface where the old faucet sat. Use a scraper or old credit card to remove any old caulk or mineral deposits. Wipe it dry with a cloth.
Installing the new faucet
Open the box and lay out all the parts. Most single handle faucets come with a rubber gasket, a metal washer, and mounting bolts. Read the instruction sheet that came with your faucet—the order in which you stack these parts matters, and it varies by brand.
Insert the faucet spout through the hole in the sink from above. The gasket and washer go underneath the sink, in the order shown in your instructions. Thread the mounting bolts through the washer and gasket, then through the threaded holes on the faucet body. Tighten these bolts by hand first, then use a wrench to snug them down. Do not over-tighten; you are aiming for snug, not crushing force. If the faucet starts to rock or move when you tighten one bolt, loosen it and tighten the other one a little, then go back and forth until both are even.
Some faucets have a collar that screws down over the mounting bolts to hide them. If yours does, screw this on now.
Reconnecting the water supply lines
Look at the water supply connections on your new faucet. They will be labeled hot and cold, or marked with red and blue tape. Connect the hot water line to the hot connection and the cold water line to the cold connection. If you reverse them, the handles will work backwards.
Hand-tighten the compression nuts first. Then use an adjustable wrench to turn them another half-turn clockwise. This is tight enough; you do not need to crank hard. If a connection leaks after you turn the water back on, you can tighten it a bit more, but most leaks at compression fittings are caused by over-tightening, which damages the seal.
Testing for leaks and finishing
Turn the shutoff valves back on slowly. Turn them counterclockwise until they stop—do not force them. Open the faucet handle and let water run for 10 to 15 seconds to flush air out of the lines.
Watch the connections under the sink while the water is running. Look at the compression nuts where the supply lines meet the faucet, and at the bolts holding the faucet down. Water should not drip from any of these spots. If you see a drip, turn off the water, wait a minute, and tighten that connection a quarter-turn with a wrench. Turn the water back on and check again.
Check the area where the faucet comes through the sink. A small amount of water under the sink is normal—it is condensation from cold water pipes. But if water is actively dripping from the base of the faucet where it enters the sink, the gasket may not be seated properly. Turn off the water, remove the mounting bolts, lift the faucet slightly, and check that the gasket is centered and not twisted. Reinstall and test again.
Once everything is dry and no leaks are visible, you are done. Run the faucet for a minute to make sure both hot and cold water flow normally and the handle moves smoothly.
Common problems and how to fix them
If water leaks from under the sink at the compression nuts, the fitting may not be tight enough, or the ferrule (a small metal or plastic ring inside the nut) may be damaged. Turn off the water, disconnect the line, and look inside the nut. If the ferrule is cracked or missing, you will need a new supply line. If it looks fine, reconnect and tighten the nut another quarter-turn.
If the faucet handle is hard to move or feels stuck, you may have tightened the mounting bolts too much and bent the faucet body. Loosen the bolts slightly and try again. The handle should move smoothly with light pressure.
If water sprays out around the base of the spout when you turn on the faucet, the gasket is not sealing. Turn off the water, remove the mounting bolts, and check that the gasket is sitting flat and centered. If it is torn or cracked, you need a replacement gasket—most hardware stores sell them individually.
When to call a plumber
If the shutoff valves under your sink will not turn or are leaking, stop and call a plumber. A stuck valve can break if you force it, and a leaking valve means water is escaping into your cabinet. A plumber can replace these valves safely.
If you cannot reach the mounting bolts because of the cabinet layout, or if your sink has an unusual configuration, a plumber can handle the installation. Some older sinks or custom installations require different techniques.
If water leaks from the base of the faucet after you have checked the gasket and tightened the bolts, the faucet body itself may be cracked. This is rare with new faucets, but if it happens, the faucet is defective and should be returned or replaced under warranty.
Frequently Asked Questions
Can I install a new faucet without turning off the water?
No. Even with the shutoff valves closed, water is trapped in the lines and will spill when you disconnect them. Turning off the water first keeps your cabinet dry and makes the job much cleaner and faster.
What if my sink has three holes but my new faucet only needs one?
Most single handle faucets come with a cover plate or escutcheon that hides the unused holes. If yours did not, you can buy a decorative cap or plate at any hardware store that fits a standard sink hole. Measure the hole diameter before you shop.
Do I need plumber's tape on the water line connections?
No. Modern kitchen faucets use compression fittings, which do not need tape. Tape is used on threaded connections where one piece screws into another. Compression fittings use a ferrule and nut, and tape can actually interfere with the seal.
How tight should the mounting bolts be?
Tight enough that the faucet does not rock or move when you push on it, but not so tight that you have to strain with a wrench. If you can tighten it comfortably with one hand on the wrench, it is probably right. If you need both hands or a long wrench for leverage, you are over-tightening.
What if water is still running after I close the shutoff valve?
The shutoff valve is not working. Stop and find your main water shutoff valve, which is usually in the basement or outside near the foundation. Turn that off before you disconnect anything. Once the main is off, you can work safely, and you can call a plumber to replace the broken shutoff valve later.