How to Install a New Kitchen Sink Faucet

Replacing a kitchen faucet is one of those projects that feels more complicated than it actually is. The thing sitting under your sink that delivers water is fundamentally simple—it's just pipes and connections. What makes people nervous is working in that cramped, wet space under the cabinet, but once you understand the sequence, it's mechanical and straightforward. A new faucet transforms the whole sink experience: better spray patterns, longer reach, easier cleaning. And you'll save the hundred-plus dollars a plumber would charge just to show up.

1. Stop the water first. Locate the shutoff valves under the sink—they're the oval knobs on the hot and cold water lines coming up through the floor or wall. Turn both clockwise until they stop. If you can't find shutoff valves under the sink, go to the main shutoff for the house. Once the valves are closed, turn on the faucet at the sink to release any remaining pressure in the lines. You should see the water stop flowing.
2. Make space to work. Remove everything stored under the sink. Place a bucket or towel on the floor to catch water still in the lines. You need clear, dry access to see what you're disconnecting. A headlamp or work light clipped to the rim of the cabinet is essential—the space under a sink is dim.
3. Disconnect both supply lines. Locate where the hot and cold water lines connect to the bottom of the old faucet. They're usually connected with compression fittings—the nuts that tighten around the line. Use an adjustable wrench to hold the fitting while you turn the nut counterclockwise with another wrench. Once both lines are loose, unscrew them by hand and pull them away. Water may still drip—catch it with your bucket.
4. Free the old faucet. Reach up from underneath the sink to where the faucet base passes through the countertop. You'll feel a mounting nut (or nuts if it's a three-hole faucet) holding the faucet down. Use a basin wrench—a specialized wrench with a bent head that fits in tight spaces—or an adjustable wrench to turn these counterclockwise. Once they're loose, unscrew by hand. The old faucet should now lift out of the countertop.
5. Clear the mounting surface. With the old faucet out, look at the holes in your sink or countertop. Scrape away any old caulk, mineral deposits, or debris with a putty knife. Wipe the area clean and dry with a cloth. This surface needs to be clean for the new faucet to seal properly and sit flat.
6. Set and seal the base. Check your new faucet's instruction sheet to understand which holes it needs. If you have a single-hole setup and the faucet requires two, you may need an escutcheon plate to cover the extra hole. Position the faucet so the spout clears the sink bowl and the handles sit level. Apply a thin bead of plumber's putty or silicone caulk around the base of the faucet where it meets the sink—this prevents water from seeping down into the cabinet.
7. Secure from underneath. From under the sink, slide the mounting washer and nut onto the threaded post(s) of the new faucet. Hand-tighten first, then use the basin wrench to snug them down. Don't overtighten—you want the faucet held firmly, but stripped threads or cracked bases happen if you muscle it. Once the faucet is stable and doesn't wiggle, it's tight enough.
8. Thread the water lines. Attach the supply lines to the faucet inlet ports—usually marked H for hot and C for cold. Use your hands first to thread the compression fittings onto the threaded posts, then snug them down with a wrench. The connection should be tight enough that you can't wiggle it by hand, but you don't need to apply body weight. Hand-tight plus a quarter turn with the wrench is usually correct.
9. Hunt for leaks. Slowly turn on both shutoff valves by rotating them counterclockwise. Start with a quarter turn, wait a moment, then another quarter turn. Let water run through the faucet for 30 seconds at both hot and cold. Inspect all three connection points—the hot line, the cold line, and any spray head hose—for drips. If you see a drip, turn the nut that feeds that line an eighth turn counterclockwise with your wrench while holding the fitting steady with another wrench.
10. Test all flows. If your new faucet came with an aerator—the screw-on strainer at the tip of the spout—thread it in by hand and snug it gently. Run hot water, then cold water, testing both pressure and temperature. If you have a spray head or pull-out wand, test that too, making sure it flows and retracts smoothly. Let the water run for a full minute to make sure everything stays connected and no new leaks appear.
11. Waterproof the seal. Once everything is tested and dry, apply a bead of silicone caulk around the base of the faucet where it meets the sink or countertop. Use a caulk gun, apply a smooth, continuous line, and smooth it with a wet finger or caulk tool. This prevents water from splashing under the faucet and seeping into the cabinet. Let it cure for 24 hours before splashing water directly at the base.
12. Final verification. Once caulk is dry, replace items under the sink gradually, checking for any leaks as you put things back. Run the faucet one more time at both hot and cold, and look underneath for any signs of dripping. Check hot and cold shutoff valves one more time to make sure they're in the fully open position—a partially closed valve will reduce pressure and create frustration later.