Replace a Leaking Kitchen Sink Faucet

Leaking kitchen faucets waste water and leave stains on your sink. A drip from the spout or a slow leak under the deck means the internal seals have worn out, and repair kits rarely last. Replacement is simpler than you'd think—the job is about disconnecting old lines and tightening new ones. You don't need a plumber for this. What matters is working methodically in a tight space, having a towel ready for water spillage, and knowing that turning off water at the shutoff valve under the sink is non-negotiable. A new faucet gives you a chance to upgrade style too: better spray patterns, smoother handles, or a pulldown spout that makes daily work easier.

1. Shut Off Water First. Look under the sink and locate the two shutoff valves (one for hot, one for cold) where the supply lines come in from the wall. Turn both valves clockwise until they stop—no force needed. If the valves are stuck or absent, locate your home's main water shutoff and close that instead. Once closed, turn on the kitchen faucet at the sink to release pressure in the lines.
2. Unthread Both Supply Lines. Position a towel or shallow bucket under the faucet connection point. Using an adjustable wrench, loosen the compression fitting nuts that connect the supply lines to the faucet base. Turn counterclockwise until they unscrew by hand. Water will spill—that's normal. Disconnect both hot and cold lines completely.
3. Loosen Mounting Nuts Evenly. From under the sink, locate the large nuts that hold the faucet to the deck above. Use a basin wrench (a specialized tool with a rotating head that fits tight spaces) or a regular wrench to loosen these nuts counterclockwise. You typically need to unscrew two nuts, one on each side of the faucet body. Loosen them until the faucet lifts free from the countertop.
4. Lift Out Old Faucet. With both supply lines disconnected and the mounting nuts fully removed, push the old faucet up from below. It will come free from the top side of the deck. Lift it out and set it aside. You now have an empty hole at the sink deck.
5. Scrape Deck Clean. Wipe away any old caulk, mineral deposits, or debris from the sink deck where the old faucet sat. Use a scraper or old credit card to remove stubborn buildup. This ensures the new faucet sits flat and sealed. A clean surface prevents leaks later.
6. Center And Level Faucet. Place the new faucet into the hole at the sink deck from the top. Make sure it sits straight and level. The spout should point toward the basin and not toward the backsplash. From underneath, check that the base is centered and aligned before you tighten anything.
7. Tighten Mounting Nuts Evenly. From under the sink, thread the mounting nuts that came with the faucet onto the threaded posts. Hand-tighten them first to seat the faucet properly. Then use a basin wrench to tighten the nuts snugly—firmly, but not so hard that you crack the sink deck. Alternate between left and right nuts to pull the faucet down evenly.
8. Thread Supply Lines Snug. Take the hot water supply line and thread it onto the hot connection at the faucet base (usually marked red or H). Use an adjustable wrench to tighten the compression fitting—hand-tight plus one quarter turn. Repeat with the cold line. Do not over-tighten; that's the leading cause of leaks at the fitting.
9. Restore Water And Check Leaks. Turn both shutoff valves counterclockwise slowly to restore water pressure. Start with a quarter turn, then check under the sink for leaks before opening all the way. Once both valves are fully open, run the faucet through hot, cold, and both together. Check every connection point under the sink for drips.
10. Seal Perimeter With Caulk. If there's a gap between the faucet base and the sink deck, apply a bead of silicone caulk around the perimeter. Wet your finger, run it along the caulk line to smooth and seat it, then let it cure per the caulk manufacturer's instructions (usually 24 hours). This prevents water from running down and pooling under the sink.
11. Fine-Tune Water Flow. Most new faucets have a removable aerator screen at the spout tip. If water pressure feels low, unscrew the aerator, rinse any debris, and reinstall. If it still feels weak, check that the shutoff valves under the sink are fully open—sometimes people leave them slightly closed.