How to Fix a Leaky Kitchen Faucet

Find the model number first. It's stamped on the faucet body at the base of the spout, or on a tag on the supply lines. Without it, you cannot reliably buy the correct cartridge — and every major brand uses a proprietary cartridge geometry.

Seven components — seven leak scenarios

Turn both angle stop valves clockwise to fully closed. Open the faucet hot and cold to drain lines. Clear everything from under the sink — you need unobstructed flashlight access. Lay a towel and set a small bucket. Photograph the supply line connections and the handle assembly before touching anything.

Remove handle cap, unscrew handle screw (Phillips or Allen), lift handle. Extract retaining clip or nut (Moen: U-clip straight up with needle-nose pliers; Kohler: retaining ring unscrews counterclockwise; Delta single-lever: unscrew cap and lift ball assembly). Remove old cartridge, photograph orientation. Install new brand-matched cartridge in same orientation. If hot/cold are reversed after reassembly, the cartridge is 180° off — remove and rotate.

With the cartridge removed, use a pick to lift each O-ring on the cartridge shaft. Replace with exact-diameter matches coated in plumber's silicone grease. Most kitchen faucets have 2–4 O-rings of different diameters along the cartridge body. Replace all of them while the cartridge is out — a single worn O-ring costs $0.50 and takes 2 minutes to swap.

Loosen the faucet mounting nut with a basin wrench from below. Lift the faucet enough to clean old putty from escutcheon underside and sink deck. Apply a 3/16-inch rope of plumber's putty (chrome finish) or clear silicone (brushed nickel, oil-rubbed bronze, or matte finishes — never use oil-based putty on porous finishes). Press the faucet down, tighten the mounting nut until snug, clean squeeze-out with a wooden stick.

Disconnect at both ends — angle stop and faucet inlet. Replace both supply lines even if only one is leaking. New braided stainless lines: $8–$15 each, 20-minute install. Torque: hand-tight plus one-quarter turn with pliers only. Overtightening deforms the brass ferrule and creates the leak you were trying to prevent.

Disconnect the head coupling (quick-connect ring down and pull, or unscrew counterclockwise). Thread the hose out through the faucet body from below. Thread the new hose in, attach the counterweight (it keeps the head retracted — do not skip this), connect the head coupling. Confirm the head retracts smoothly when released.

Remove the spout by unscrewing the spout ring counterclockwise. Inside the body: a small cylindrical diverter valve, 1/2 to 3/4 inch diameter, unscrew counterclockwise with a socket. Take it for a brand-matched replacement ($12–$20). Thread in new diverter hand-tight plus one-quarter turn. Reassemble spout, test spray and spout separately.

Unscrew the aerator from the spout tip, soak 30 minutes in white vinegar, rinse and reinstall. Open supply valves slowly. Run hot and cold at full flow for 30 seconds. Dry the under-sink area and re-inspect every connection with a flashlight after 2 minutes. No drips = repair complete.