Kitchen Faucet Leaking
A leaking kitchen faucet is one of the most common plumbing calls — and in most cases, it is a quick DIY fix. The leak location tells you almost everything: water pooling at the base of the faucet means worn body O-rings; water dripping under the sink usually means a loose or failed supply line connection or a corroded shutoff valve; a wet spot near the sprayer typically means the sprayer hose diverter or hose connector has failed. This guide walks through each scenario in order of likelihood so you can stop the leak without calling a plumber.
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Common Symptoms
- Water puddle on the countertop around the base of the faucet after use
- Water dripping or pooling inside the cabinet under the sink
- Sprayer hose leaks at the connection point or along the hose body
- Visible drip from the supply line connections under the sink
- Cabinet under the sink smells of mildew or shows warped wood
- Faucet handle leaks at the base when turned on
- Water stains or mineral deposits on cabinet floor under the sink
Most Likely Causes
- 1
Worn Body O-Rings (Most Common Base Leak)
Single-handle pull-down and pull-out kitchen faucets use rubber O-rings to seal the faucet body against the mounting deck. Over time — usually 5–10 years — these O-rings dry out and crack from mineral deposits and heat cycling. When they fail, water that enters the faucet body leaks out around the base rather than up through the spout. Replacing the O-rings typically costs $5–$15 and takes 30–45 minutes.
- 2
Loose or Failed Supply Line Connection
The flexible braided supply hoses that connect the shutoff valves to the faucet inlets are under constant low-level stress from water pressure. Over time the compression fittings loosen, or the rubber gasket inside the fitting hardens and cracks. A slow drip from a supply line connection is easy to miss until water damage has occurred inside the cabinet. Tightening the fitting one-quarter turn stops most minor drips; failed fittings need the line replaced.
- 3
Corroded or Leaking Angle Stop Shutoff Valve
The angle stop shutoff valves (the small valves under the sink that control hot and cold supply to the faucet) develop packing nut leaks over years of service — especially on older valves that have not been operated in years. A small drip at the packing nut on the valve body itself is often mistaken for a supply line leak. Tightening the packing nut one-quarter turn stops most valve body drips; severely corroded valves need replacement.
- 4
Sprayer Hose Diverter Failure
Pull-down and pull-out kitchen faucets route water through the spout or the spray head via a diverter valve inside the faucet body. When the diverter wears out, water can leak back through the hose connection, the quick-connect fitting at the spray head, or around the diverter seat inside the body. Diverter replacements are faucet-model-specific and typically cost $10–$30.
- 5
Deteriorated Deck Gasket or Mounting Nuts
Most kitchen faucets mount through holes in the sink deck and are sealed with a rubber deck gasket between the faucet base and the sink surface. If the mounting hardware has loosened over time or the gasket has dried out and shrunk, water that splashes around the base can migrate down through the deck hole and drip inside the cabinet — appearing to be a supply line leak. Tightening the mounting nuts and replacing the deck gasket (with plumber's putty if no gasket is provided) seals this pathway.
- 6
Failed P-Trap or Drain Connection (Not the Faucet)
Water inside the cabinet is sometimes misdiagnosed as a faucet leak when the actual source is the drain: a loose P-trap slip joint, a cracked P-trap arm, or a failed drain basket gasket at the sink basin. Check the drain plumbing by running the sink while looking inside the cabinet — drain leaks only appear when the sink drains, not when the water is running, which distinguishes them from supply-side faucet leaks.
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Quick DIY Checks
Always turn off the angle stop shutoff valves under the sink before disconnecting any supply lines or removing the faucet. If the shutoff valve is seized and will not close, shut off the main house water supply before proceeding.
Do not over-tighten supply line fittings — braided stainless supply lines use plastic or nylon compression nuts that will crack or strip with excessive force. Hand-tight plus one-quarter turn with a wrench is sufficient for a leak-free seal.
- 1Step 1 — Locate the leak source precisely: dry all surfaces under the sink and around the faucet base with paper towels. Run water for 60 seconds with the sprayer docked, then inspect under the sink and around the faucet base. Note exactly where water appears and whether it shows up while the faucet runs (supply/faucet body leak) or only after draining (drain connection leak). This diagnosis step determines which repair to perform.
- 2Step 2 — Check supply line connections first: with the water running, look at the threaded connections where the supply lines meet the bottom of the faucet inlets and where they connect to the shutoff valves. Even a very slow drip will appear as moisture. If connections are wet, turn off the shutoff valve, dry the fitting, and use an adjustable wrench to snug the fitting one-quarter turn clockwise. Do not overtighten — modern supply lines use nylon compression fittings that crack if over-torqued. Restore water and recheck.
- 3Step 3 — Check shutoff valve packing nuts for weeping: look at the body of each shutoff valve (not the connection, but the valve body itself) for a wet ring just behind the handle stem. This is the packing nut. Use an adjustable wrench to tighten the packing nut one-quarter turn clockwise. If the nut is already tight and still weeping, or if the valve body is visibly corroded, replace the shutoff valve — this is a moderately involved repair that requires turning off the main water supply.
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Repair vs Replace
Kitchen faucet leaks are almost always fixable with inexpensive parts — a supply line replacement runs $8–$15, O-ring kits $5–$15, and even a diverter $10–$30. Faucet replacement makes sense only if the faucet body is cracked, the finish is degraded, or multiple internal components have failed simultaneously and parts are no longer available for an older model. Most faucets are repairable for under $30 in parts and 30–60 minutes of work.
Est. Repair Cost
$5–$40 (supply line, O-rings, or gasket kit)
Est. Replacement Cost
$150–$500 for a new mid-range kitchen faucet plus installation labor
Recommended Tools & Parts
- Buy on Amazon →
Eastman Stainless Braided Supply Line — 3/8" Compression x 1/2" FIP (2-Pack, 12-inch)
Heavy-duty braided stainless steel supply lines with CPVC core for kitchen faucet hot and cold inlets. 3/8-inch compression end connects to standard angle stop shutoff valves; 1/2-inch FIP end threads onto faucet inlet nipples. Two lines needed per standard kitchen faucet. Available in 12, 16, and 20-inch lengths — measure before ordering.
$10–$18
- Buy on Amazon →
Danco Universal O-Ring Kit (Assorted Sizes, 36-Piece)
Assorted rubber O-ring set with the most common sizes used in kitchen faucet body seals, cartridge housing seals, and sprayer hose connectors. Includes 36 O-rings in multiple diameters to match most residential faucet brands. Coat O-rings with plumber's silicone grease before installation for a reliable long-lasting seal.
$6–$12
- Buy on Amazon →
Moen Kitchen Faucet Replacement Hose Kit (Pull-Down, Model-Specific)
OEM replacement hose kit for Moen pull-down and pull-out kitchen faucets. Includes the spray hose, quick-connect fittings, and counterweight. Verify your Moen model number before ordering. Third-party universal hose kits are available for non-Moen faucets — match hose diameter and quick-connect type.
$15–$35
- Buy on Amazon →
Harvey's Silicone Grease (Plumber's Silicone, 1.5 oz)
Food-safe silicone grease for lubricating and sealing rubber O-rings and cartridge seals during faucet repair. Prevents O-ring tearing during installation and extends service life. Compatible with all rubber compounds used in residential faucets.
$6–$10
- Buy on Amazon →
Ridgid Basin Wrench (1/4" to 3/4" Capacity, 16-inch Telescoping)
Basin wrench designed to reach faucet mounting nuts and supply line fittings in the tight space behind the sink. The swiveling jaw grips in either direction for tightening or loosening. Essential for removing or tightening faucet mounting hardware in confined under-sink spaces.
$20–$35
Links are Amazon affiliate links (tag: fixitfastai-20). Prices are estimates.
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Related Repair Guides
This section combines editorial `relatedSlugs` from the article source with metadata-based matches so each guide links deeper into the repair library.
Sink Faucet Dripping
Dripping faucet wasting water and driving you crazy? In most cases a worn cartridge or O-ring is the culprit — a $10–$25 part and 30–60 minutes fixes it permanently.
Read guide →Bathroom Sink Slow Drain — How to Clear a Sluggish Bathroom Sink in 20 Minutes
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Read guide →Toilet Running Constantly
Hear water trickling into the bowl constantly? A worn flapper is the most common cause — a $5 fix.
Read guide →Water Heater — No Hot Water
No hot water at all or only lukewarm? Start with the reset button — then check the heating element or pilot light.
Read guide →Dripping Faucet Repair — Ball, Cartridge, Ceramic Disc & Compression Fix Guide
A faucet dripping once per second wastes ~3,000 gallons/year and adds $15–25 to your water bill. Covers all four faucet types — compression, ball, cartridge, and ceramic disc — with exact part numbers and step-by-step procedures.
Read guide →Outdoor Faucet Not Working: Hose Bib Repair Guide
Outdoor faucet with no water, low pressure, or a drip from the stem? This guide covers freeze damage inspection, packing nut and washer replacement, vacuum breaker failure, and when to replace the whole hose bib.
Read guide →Keep Exploring
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Frequently Asked Questions
- My kitchen faucet leaks only when the water is running — is that different from a dripping faucet?
- Yes — a faucet that leaks only when running (at the base, under the sink, or at the sprayer) is a supply-side or body seal issue, not a dripping spout issue. A dripping spout that runs between uses points to a worn cartridge or valve seat inside the faucet. This guide covers flow-activated leaks (base, supply lines, sprayer); see the Sink Faucet Dripping guide for spout drip repairs.
- How do I know if my supply line needs replacing vs. just needs tightening?
- Try tightening the connection one-quarter turn with an adjustable wrench. If the leak stops and does not return within 24 hours, tightening was sufficient. If the leak continues after tightening, or if the line itself is discolored, kinked, or the braided sleeve is separating, replace the line. Supply lines cost $8–$15 and are a 15-minute replacement — always worth replacing if tightening does not hold, since a failed supply line under pressure can flood a cabinet overnight.
- Can I fix a kitchen faucet O-ring leak without replacing the whole faucet?
- In most cases yes. Even faucets 15+ years old can have O-rings replaced if the faucet body is not cracked. The challenge is sourcing the correct O-ring size — bring the old O-ring to a hardware store or measure the inner diameter, outer diameter, and cross-section thickness to match. For major brands (Moen, Delta, Kohler, Price Pfister), O-ring kits are sold as model-specific repair packs. For off-brand faucets, a Danco universal assortment covers most sizes.
- The leak is inside the cabinet but I cannot tell if it is the faucet or the drain — how do I tell them apart?
- Turn on the faucet and let it run without draining (plug the sink drain). Watch inside the cabinet for 60 seconds. If water appears, the leak is supply-side (faucet body, supply lines, or shutoff valves). Now unplug the drain and let the sink empty while watching again. If water only appears during draining, the leak is in the drain assembly (P-trap, basket strainer gasket, or drain arm). Many cabinets have both leaks simultaneously from years of moisture, so check both.
- How long do kitchen faucet supply lines last?
- Standard braided stainless steel supply lines have a typical service life of 8–10 years. The rubber inner hose and compression fittings degrade over time. Many plumbers recommend replacing supply lines when a faucet is replaced, or proactively every 10 years — especially on washing machine hoses and water heater connections, where a burst causes immediate flooding. Inspect supply lines annually for bulging, discoloration, or corrosion at fittings.