This is the complete kitchen faucet leak repair guide. It covers every leak location specific to kitchen faucets: the spout drip (valve cartridge), the handle base (cartridge O-rings), under the sink at the supply line connections (supply line or angle stop), at the base of the faucet where it meets the sink deck (escutcheon plate or deck seal), the sprayer hose connection (pull-out or pull-down faucets), the sprayer head itself, and the side sprayer diverter valve. A generic guide to faucet leak repair by valve type is available at How to Fix a Leaky Faucet and covers compression, cartridge, ball, and ceramic disc valves broadly. This guide focuses on kitchen faucet anatomy and the leak points that are unique to kitchen installations.
Kitchen faucets differ from bathroom faucets in several significant ways: the faucet body is typically larger and mounted through a wider escutcheon plate or deck cover, hot water demand is higher and more sustained (longer dishwashing cycles), the pull-out or pull-down spray head introduces a hose component that bathroom faucets lack, and the spray diverter is a kitchen-exclusive valve. Each of these creates leak points not found in a typical bathroom installation.
Time: 30 minutes (supply line) to 2 hours (full cartridge + deck seal). Cost: $8–$60 depending on scope. Difficulty: Beginner to Intermediate. Permit required: No. Tools: Basin wrench, adjustable pliers, Allen key set, flashlight for under-sink inspection.
Kitchen Faucet Anatomy — Know What You Are Looking At
Before any repair, identify each component by name. Kitchen faucet failures are almost always at one of seven points. Knowing the name of each part prevents the experience of buying the wrong component and making a second hardware store trip.
The seven kitchen faucet components most likely to leak
Valve cartridge. The internal valve that controls hot-cold mixing and flow volume. In modern kitchen faucets this is a ceramic disc cartridge or a ceramic ball cartridge. Located inside the faucet body under the handle. Causes: spout drip, handle leak.
Cartridge O-rings. Rubber rings that seal the cartridge body to the faucet housing. Separate from the cartridge seals — they surround the cartridge cylinder and prevent water from bypassing the cartridge. Causes: water at the handle base or around the faucet body.
Supply lines. Braided stainless steel or chrome-plated copper tubes running from the angle stop shut-off valves to the faucet inlet ports. The most common under-sink leak source. Connection fails at the compression fitting at the angle stop, the nut at the faucet inlet, or through a cracked supply line body. Causes: under-sink puddles.
Escutcheon plate / deck cover. The decorative plate that covers the mounting holes in the sink deck, sealing the gap between the faucet body and the sink surface. An escutcheon leak appears as water at the base of the faucet on the sink deck after every use. Causes: failed plumber's putty or silicone seal under the plate.
Pull-out / pull-down spray hose. The flexible hose inside the faucet body that feeds the spray head. On pull-out and pull-down faucets, this hose is the most common failure point after 5–8 years. Causes: leak at the hose-to-head coupling, at the inlet connection, or through a crack in the hose body.
Spray diverter. The valve inside the faucet body that routes water to the spray head when the spray trigger is activated and back to the spout when released. Found in faucets with a separate side sprayer (not pull-out). Causes: low spray pressure, constant drip from the spout when the sprayer is in use.
Aerator. The mesh screen assembly at the tip of the spout that mixes air into the flow. Not a leak source itself, but mineral buildup in the aerator increases back-pressure upstream, which accelerates wear on cartridge seals and O-rings. A clogged aerator should be cleaned at the same time any cartridge repair is performed.
Leak Location Diagnosis — Match Location to Component
Water dripping from the spout when the faucet is off
The valve cartridge is not sealing fully when the handle is in the off position. This is the most common kitchen faucet complaint. The fix is cartridge replacement (if ceramic disc or ceramic ball type) or seat washer replacement (if compression type). Note the brand and model number before buying a replacement cartridge — cartridges are brand-specific and not interchangeable. Delta, Moen, Kohler, Grohe, American Standard, and Price Pfister each use proprietary cartridge geometry. The model number is typically stamped on the faucet body at the base of the spout, or on a tag attached to the supply lines.
Water at the base of the faucet on the sink surface
The escutcheon plate seal (plumber's putty or silicone) has failed, or the cartridge O-rings on the faucet body are worn, allowing water to run down the faucet body and under the plate. Distinguish between the two: wipe the sink dry, then run the faucet and watch whether water appears even when the handle is not being touched (escutcheon seal failure, water entering through the deck gap) or only when the handle is moved (cartridge O-ring failure, water bypassing the cartridge during use).
Dripping or puddle under the sink
The most common under-sink leak is at the compression fitting connecting the supply line to the angle stop shut-off valve. These fittings loosen over years of vibration and water hammer. A second common source is the nut connecting the supply line to the faucet inlet port. Dry the under-sink area completely, run water, and watch with a flashlight to pinpoint the exact drip location before tightening or replacing anything.
Spray head drips or spray hose leaks
On pull-out and pull-down faucets, the hose connecting the spray head to the faucet body has a coupling at the head end and a connection at the faucet body inlet. The head-end coupling uses a small O-ring that deteriorates with heavy use. The body-end connection uses a compression fitting. Replacement spray hoses are available by brand and are typically $15–$30. On older side-sprayer faucets, a worn diverter valve inside the faucet body causes the spray to dribble even when not in use, or the spray loses pressure progressively over months — diverter replacement is covered below.
What You Will Need
Tools
Basin wrench (for reaching supply line nuts in confined under-sink space)
Adjustable pliers (channel-lock, 10-inch)
Allen key set (metric and SAE — faucet set screws are often metric)
Flathead and Phillips screwdrivers
Flashlight or headlamp for under-sink work
Plumber's grease (silicone-based, for O-ring installation)
Plumber's putty or clear silicone sealant (for escutcheon re-sealing)
Clean white towels and a small bucket
Parts — buy after diagnosis
Replacement cartridge (brand-specific — model number required), $10–$35
O-ring assortment set (metric and SAE, $8–$12) for body seals
Braided stainless supply lines, 12-inch or 20-inch (match existing length), $8–$15 per line
Spray hose replacement (brand-specific for pull-out/pull-down), $15–$30
Diverter valve (brand-specific for side-spray faucets), $8–$20
Aerator replacement (match thread size — typically 15/16-inch or 55/64-inch), $4–$8
Step-by-Step Repair by Component
Step 01 · Shut off supply valves and clear under-sink space
Turn both angle stop valves under the sink clockwise to fully closed. Open the faucet hot and cold to release line pressure and drain the supply lines. Clear the under-sink cabinet completely — you will be working in a confined space with a flashlight and tools, and a crowded cabinet makes every step harder and longer. Lay a clean towel under the work area. Have a small bucket ready to catch residual water when supply lines are disconnected.
Step 02 · Replace the valve cartridge (for spout drip)
Kitchen faucets are almost exclusively single-handle cartridge or ceramic disc type. Remove the handle: find the decorative cap on top (pry with a small flathead), remove the screw underneath (Phillips or Allen), and lift the handle off. The cartridge housing may be secured by a retaining nut, a retaining clip, or an internal retaining ring. For Moen: the cartridge is held by a U-shaped brass clip — pull it straight up with needle-nose pliers. For Delta single-handle ball-type: unscrew the cap counterclockwise and follow the ball faucet procedure in the general faucet repair guide. For Kohler: a retaining ring unscrews counterclockwise. Take the old cartridge to the hardware store or note the brand and model number to buy the correct replacement. Install the new cartridge in the same orientation as the old — a photograph before removal is essential. Note the orientation notch or flat on the cartridge that aligns with the valve body.
Step 03 · Replace cartridge O-rings (for base or body leak)
With the cartridge removed, inspect the O-rings on the cartridge body — the cylindrical rubber rings that seal the cartridge to the valve body bore. On most kitchen faucets there are two to four O-rings of different diameters along the cartridge shaft. Remove each with a pick tool or a small flathead screwdriver, being careful not to score the cartridge body or the valve seat. Bring the old O-rings to the hardware store for exact matches, or purchase an O-ring assortment and select matching diameters. Coat each new O-ring with plumber's silicone grease before installation to prevent tearing during assembly. Reinstall the cartridge with the new O-rings, replace retaining hardware, and reinstall the handle.
The escutcheon plate is the decorative base cover that sits on the sink deck and conceals the mounting holes. To re-seal it, the faucet must be removed from the sink — or at minimum, the escutcheon plate must be lifted enough to access the underside. On most kitchen faucets, the faucet body is secured by a mounting nut under the sink driven with a basin wrench. Loosen the mounting nut, lift the faucet body, clean the old putty or silicone from both the underside of the escutcheon and the sink deck surface. Apply a rope of plumber's putty around the underside perimeter of the escutcheon, press the faucet back down, and tighten the mounting nut from below until snug. Remove squeeze-out putty from the deck surface with a wooden stick or plastic scraper. Do not use metal tools on finished sink surfaces — they scratch enamel and stainless steel immediately. Reconnect supply lines and test.
Step 05 · Replace the supply lines (for under-sink drip)
Braided stainless supply lines are the most reliable and affordable solution for any under-sink supply line leak. Even if only one connection is leaking, replace both supply lines while you have the water off — the second is equally old and will fail within months. Disconnect the supply line at the angle stop by holding the valve body with pliers and unscrewing the compression nut counterclockwise. Disconnect the upper end at the faucet inlet port — typically 1/2-inch IPS thread, either a brass compression nut or a push-connect fitting. Take the old supply line to the hardware store to match the length (12-inch, 20-inch, or custom) and connection type. Install new braided stainless lines with hand-tight connections plus one-quarter turn with pliers. Do not overtighten — the brass compression nut seats against a rubber cone, and overtightening cuts the cone rather than sealing it. Turn on supply valves and check for drips at both connection ends.
On pull-out faucets (spray head slides forward out of the spout), the spray hose connects to the base of the spray head via a quick-connect or threaded coupling, runs down through the faucet body, and connects to the water supply at the faucet inlet inside the cabinet. To replace: disconnect the head coupling first (pull the quick-connect ring down and pull the hose out, or unscrew the threaded connection counterclockwise), then pull the entire hose assembly out through the faucet body. The replacement hose typically comes with a weight attached — a small counterweight that keeps the hose retracted when the spray head is put back. Thread the new hose through the faucet body from below, attach the counterweight per the replacement hose instructions, and connect the head coupling. Confirm the hose moves freely and the counterweight re-retracts the head when released. On pull-down faucets (head pulls down rather than forward), the procedure is identical but the hose routing through the body is vertical.
Step 07 · Replace the spray diverter (for side-spray faucets with low pressure or constant spout drip)
Side-spray faucets — faucets with a separate spray nozzle on a short hose beside the main spout — use a diverter valve inside the faucet body to redirect water flow. The diverter is a small cylindrical valve, typically 1/2 inch to 3/4 inch diameter, threaded into the faucet body above the cartridge. Access it by removing the spout (unscrew the spout ring counterclockwise by hand or with strap wrench) and lifting the spout off the body. The diverter is visible inside the body — unscrew it counterclockwise with an appropriately-sized socket. Take it to the hardware store for a brand-matched replacement. Thread in the new diverter until hand-tight plus one quarter-turn, reassemble the spout, test spray pressure and spout flow separately.
Step 08 · Clean or replace the aerator
Unscrew the aerator from the spout tip (counterclockwise when facing the spout — it is reverse-threaded relative to how you stand at the sink). The aerator has two to four components: the housing, a mesh screen, a flow restrictor disc, and an O-ring. Soak in white vinegar for 30 minutes to dissolve mineral deposits. Rinse, reassemble, and reinstall. If the housing threads are stripped or the mesh is torn, replace the aerator — they are inexpensive ($4–$8) and available in two thread sizes (15/16-inch for standard spouts, 55/64-inch for faucets with smaller spout tips). A clogged aerator increases line pressure and accelerates cartridge wear; clean it whenever any other faucet repair is performed.
Step 09 · Pressure-test and inspect all connections
Turn on both supply valves slowly — not full-open in a single motion. Allow the system to pressurize over 5–10 seconds. Open the faucet to both full hot and full cold and let it run 30 seconds to purge air and any residual debris. Run the spray head if applicable. Dry the under-sink area with a towel and wait 2 minutes with the faucet running, then re-inspect every connection with a flashlight. A successful repair leaves no visible drips at any point from the angle stop valve to the aerator tip.
Common Mistakes to Avoid
Not finding the model number before buying a cartridge. Kitchen faucet cartridges are brand-specific and model-specific within brands. A photograph of the cartridge or the model number from the faucet body is the only reliable way to get the right part. "Delta kitchen faucet" encompasses over 200 distinct models with incompatible cartridges.
Overtightening the supply line compression nuts. Hand-tight plus one-quarter turn is the correct torque. Overtightening deforms the brass compression ferrule and creates a leak rather than preventing one. If a compression joint leaks after assembly, disassemble, inspect the ferrule, and re-make at the correct torque.
Installing the cartridge without replacing O-rings. A new cartridge on worn body O-rings will leak at the handle base immediately. When the cartridge is out, replace all the O-rings as a matter of course — they cost $2 and take five minutes.
Using plumber's putty on escutcheon plates made of brushed nickel or oil-rubbed bronze. Plumber's putty contains petroleum-based compounds that stain porous finishes permanently. Use clear silicone sealant for any non-chrome faucet finish.
Skipping the diverter when spray pressure is poor. A worn diverter is the most commonly missed kitchen faucet repair. Homeowners replace the spray head first (wrong), then the hose (wrong), before finally finding the $12 diverter that was the actual problem. Low spray pressure with a good spout flow = diverter, not head or hose.
Not removing the counterweight when pulling the spray hose. Pull-out spray hoses have a counterweight attached by a clip. If the hose is replaced without transferring the counterweight to the new hose, the spray head will not retract — it hangs in the bowl rather than returning to the spout cradle.
When to Call a Professional
A plumber is warranted when the angle stop valves under the sink will not close (the supply must be cut at the main); when the sink deck is cracked where the faucet mounts (faucet replacement requires a new sink or professional mounting repair); or when the leak source cannot be identified despite clearing the under-sink space and pressure-testing. Under-sink leaks that are intermittent, appear only after heavy use, or seem to come from the cabinet itself (not a visible pipe or connection) may indicate a supply line pinhole or a drain basket seal failure — distinct issues covered in separate guides. For related repairs, see How to unclog a garbage disposal and the full kitchen repair guide index.
Maintenance Schedule for Kitchen Faucets
A kitchen faucet that is maintained on schedule rarely requires emergency repair. The maintenance calendar:
Every 6 months: Unscrew and clean the aerator. Inspect supply line connections visually — look for white mineral staining (slow leak) or surface corrosion.
Every 2–3 years: Exercise the angle stop shut-off valves — turn fully closed then fully open. Valves that sit open for years seize. A seized valve cannot be turned off during an emergency.
Every 5–7 years: Replace braided stainless supply lines proactively. Supply lines have a rated service life and are the most likely source of under-sink flooding when they fail. A set of two replacement supply lines costs $12–$20 and takes 20 minutes to replace. This is the highest-value preventive maintenance in the kitchen.
On first drip from the spout: Replace the cartridge immediately. A dripping cartridge wastes 3,000+ gallons annually and the repair cost is under $30. Deferring the repair does not reduce the wear rate — the cartridge continues degrading whether the faucet is used or not.
Filed by HowTo: Home Edition. This is the Repair × Kitchen marquee guide for kitchen faucet leak repair. The kitchen faucet is the most-used plumbing fixture in the home and the one with the most repair scenarios — spout drip, body leak, supply line, escutcheon seal, spray hose, diverter, and aerator — each requiring a different diagnostic and a different part. Identifying the leak location before opening the faucet or buying parts is the repair skill this guide develops.
From spout drip to supply line flood — every kitchen faucet leak location, diagnosed and repaired.
Time: 30 min – 2 hoursCost: $8–$60Difficulty: Beginner–IntermediateBy: HowTo: Home Edition
Kitchen faucets leak in seven distinct locations, each requiring a different part and a different repair. Identifying the location before opening the faucet or buying anything is the whole repair skill. For the general guide covering all four valve types, see How to Fix a Leaky 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.
Clear silicone or plumber's putty for escutcheon resealing
The Repair Steps
Step 01
Shut off, clear the cabinet, photograph everything
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.
Step 02
Replace the valve cartridge (for spout drip)
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.
Step 03
Replace cartridge O-rings (for handle-base or body leak)
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.
Step 04
Re-seal the escutcheon plate (for deck leak)
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.
Step 05
Replace supply lines (for under-sink drip)
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.
Step 06
Replace the spray hose (for pull-out / pull-down leaks)
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.
Step 07
Replace the diverter (for low spray pressure or side-spray drip)
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.
Step 08
Clean the aerator, then pressure-test all connections
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.
Common Mistakes
Buying a cartridge without the model number — brand + model is required, brand alone is not enough
Using plumber's putty on brushed nickel or oil-rubbed bronze finishes — use clear silicone instead
Replacing the spray head for low pressure when the $12 diverter is the actual cause
Forgetting to transfer the hose counterweight to a replacement spray hose
Overtightening supply line compression nuts — one-quarter turn past hand-tight is the limit
