What you need before you start
Replacing a faucet is a task most people can do without calling a plumber, though the exact steps depend on whether your faucet is a single-handle, double-handle, or pull-down model. Before you begin, turn off the water supply valves under the sink — they are usually oval knobs on the pipes coming up from the wall or floor. If you cannot find shut-off valves under your sink, you will need to turn off the main water supply to your house, which is typically in the basement, crawl space, or outside near the meter.
Gather your tools before you start work: an adjustable wrench, a basin wrench (a specialized wrench that fits into tight spaces under the sink), a screwdriver, plumber's tape, and a bucket or towels to catch water. You will also need the new faucet itself, which should come with an instruction sheet specific to that model. Read the instructions before you remove the old faucet, because installation steps vary by brand and type.
Key Takeaways
- Turn off the water supply valves under the sink before you disconnect anything, or turn off the main water supply if those valves do not exist.
- Remove the old faucet by disconnecting the supply lines and unbolting it from underneath the sink, then clean the sink surface where the new faucet will sit.
- Install the new faucet by inserting it through the existing holes, tightening the bolts from underneath, and reconnecting the supply lines with plumber's tape on the threads.
- Test for leaks by turning the water back on slowly and checking all connections, then adjust the water temperature and flow if your new faucet has those controls.
Disconnecting the old faucet and supply lines
After the water is off, turn on the faucet to release any remaining pressure in the lines. Place a bucket under the supply lines — the flexible hoses or rigid pipes that connect the faucet to the shut-off valves. Use your adjustable wrench to loosen the nuts where these lines connect to the faucet, turning counterclockwise. Once the nuts are loose enough, you can usually unscrew them by hand. Expect some water to drip out, which is normal.
Next, look under the sink for the bolts that hold the faucet to the sink deck. These are usually large nuts on the underside of the sink, directly below where the faucet sits. A basin wrench is the right tool for this job because it has a long handle and a small head that fits into the cramped space. Loosen these bolts by turning counterclockwise until the faucet is loose enough to lift out. Some faucets also have a caulk seal around the base — if yours does, run a utility knife around the edge to break the seal before you try to remove it.
Preparing the sink and installing the new faucet
Once the old faucet is out, clean the sink surface thoroughly with a cloth and mild cleaner. Remove any old caulk, mineral deposits, or debris from the holes where the faucet will mount. If the new faucet uses the same holes as the old one, you are ready to install. If the new faucet requires different hole positions, you may need to drill new holes or have a plumber do this work.
Insert the new faucet through the existing holes, following the manufacturer's instructions for the order of parts. Most faucets have a rubber or plastic gasket that sits on top of the sink, then the faucet body, then bolts underneath that hold everything in place. Hand-tighten the bolts first, then use the basin wrench to tighten them fully — snug but not so tight that you crack the sink or strip the bolts. The faucet should not move or rock when you push on it.
Reconnecting the water supply lines
Before you reconnect the supply lines, wrap plumber's tape (also called thread seal tape or PTFE tape) around the threaded ends of the supply line connections. Wrap the tape clockwise around the threads three to four times — this creates a watertight seal. Then hand-screw the supply line nuts back onto the faucet connections, and use your wrench to tighten them an additional quarter turn. Do not over-tighten, as this can crack the fittings.
If your new faucet came with new supply lines, follow the same process: wrap the threads with plumber's tape, then screw the nuts on by hand first, then tighten with a wrench. Make sure both the hot and cold lines are connected to the correct ports on the faucet — the instructions will show you which is which.
Testing and adjusting your new faucet
Turn the main shut-off valves back on slowly, watching for leaks at every connection point. If you see water dripping from under the sink, turn the water back off and tighten that connection a quarter turn more. Once the water is fully on and there are no leaks, test the faucet by turning it on and letting it run for a minute. Check underneath the sink again to make sure no water is coming out.
If your new faucet has a pull-down sprayer or a separate spray head, test that as well. Some faucets have a lever or button to switch between regular flow and spray mode. If your new faucet has temperature or flow controls, adjust them according to the manufacturer's instructions. Most modern faucets have a limit on how far the handle can turn to prevent scalding water.
Common problems and what to do about them
If water leaks from the base of the faucet where it meets the sink, the gasket may not be seated properly. Turn off the water, remove the faucet, check that the gasket is in the right position, and reinstall it. If the leak continues, the gasket may be damaged and need replacement — most faucet manufacturers sell replacement gaskets.
If water leaks from the supply line connections, the plumber's tape may not have been applied correctly or the connection may not be tight enough. Turn off the water, disconnect the line, rewrap the threads with fresh plumber's tape, and reconnect it. If you still see leaks after tightening, the fitting itself may be damaged and the supply line may need to be replaced.
If the faucet handle is hard to move or does not turn smoothly, the cartridge or valve inside may need adjustment or replacement. Check the manufacturer's instructions for your specific model — some faucets have an adjustment screw that controls handle resistance. If adjustment does not help, the internal cartridge may be defective and should be replaced under warranty if the faucet is new.
When to call a plumber instead
If your sink does not have shut-off valves under it and you cannot locate the main water shut-off, call a plumber before you start. Attempting this work without being able to turn off the water can cause serious water damage. Similarly, if the old faucet is corroded or stuck and you cannot remove it without damaging the sink, a plumber has specialized tools to remove it safely.
If the sink deck has cracks or the holes do not line up with your new faucet, a plumber can assess whether the sink can be repaired or needs replacement. If you are not comfortable working under a sink or do not have the right tools, the cost of a plumber visit is often less than the cost of fixing water damage from a mistake.
Frequently Asked Questions
Do I need plumber's tape on every connection?
Yes, wrap plumber's tape on the threaded ends of supply lines where they connect to the faucet. Do not use it on compression fittings (the nuts that tighten directly onto smooth pipes) — those rely on a rubber washer inside the nut to seal. The instructions that come with your faucet will show you which connections need tape.
What if the old faucet has three holes but the new one only has one?
You will need to cover or fill the extra holes. Most faucet retailers sell decorative caps or plugs that match the finish of your new faucet and screw into unused holes. Alternatively, a plumber can fill the holes with epoxy or caulk if you prefer a seamless look.
How tight should I make the bolts under the sink?
Tighten the bolts until the faucet is snug and does not move, then stop. Over-tightening can crack the sink or strip the bolts. If the faucet rocks or moves after you think you are done, tighten a quarter turn more and test again.
Can I reuse the old supply lines with a new faucet?
Old supply lines can sometimes be reused if they are in good condition and the connections match your new faucet. However, if the lines are kinked, discolored, or more than 10 years old, replacing them is safer. New faucets often come with new supply lines, which is the simplest option.
What should I do if water is still running after I turn off the faucet handle?
This usually means the internal valve or cartridge is not sealing properly. Turn off the water, check that the handle is fully in the off position, and turn the water back on to test again. If water still runs, the cartridge may be defective and needs replacement — contact the faucet manufacturer for a replacement part or warranty service.