Leaky Kitchen Faucet? How to Find the Source and Fix It

Kitchen faucet leaks come from three places: the spout (dripping when off), the base (water pooling around the faucet body), or underneath (supply line connections). Each source points to a different worn part and a different repair. Identifying where the leak originates is the most important first step — and it takes about 30 seconds. The repair is usually a $10–$40 DIY job once you know what you’re replacing.

Why Is My Kitchen Faucet Leaking at the Base?

A leak at the base — water pooling around the faucet where it meets the sink deck — is almost always caused by worn O-rings around the faucet body. Kitchen faucets have one or more O-rings seated in grooves around the base and spout assembly. When these O-rings degrade or dry out, water migrates between the faucet body and the sink and surfaces at the base.

This leak often looks like the faucet is leaking from the sink itself or from the countertop — because the water travels along the underside of the faucet before appearing visibly. Dry the area completely, run the faucet for 30 seconds, and watch where water first appears. If it’s at the base of the faucet body, O-rings are the cause.

O-ring replacement is a straightforward repair: shut off the supply valves, remove the faucet spout or body (varies by model), replace the O-rings with the correct size, and reinstall. O-ring kits for most faucet brands are $5–$15 at hardware stores.

How to Fix a Leaky Kitchen Faucet Without a Plumber

Determine the leak source first (spout, base, or under-sink), then follow the appropriate repair:

Spout drip (worn cartridge):
1. Shut off supply valves under the sink
2. Remove the handle — one screw, usually under a decorative cap
3. Pull out the cartridge (straight up on most single-handle faucets)
4. Match the cartridge at a hardware store or order by model number
5. Install new cartridge, reassemble, test

Base leak (worn O-rings):
1. Shut off supply valves
2. Remove the spout by loosening the set screw at the base or the retaining nut underneath the sink
3. Slide the spout up and off — O-rings are visible in grooves on the spout body
4. Replace O-rings with the correct diameter (bring the old ones to match)
5. Reinstall, test

Under-sink leak (supply line connection):
1. Dry the area and confirm which connection is the source
2. Hand-tighten the connection first — many under-sink leaks are simply loose nuts
3. If hand-tightening doesn’t stop the leak, replace the supply line ($8–$15 for a braided stainless line)

Kitchen Faucet Dripping from Spout — How to Fix

A spout drip on a kitchen faucet is a cartridge or valve seat issue. Kitchen faucets see heavier use than bathroom faucets — more handle operations per day, more temperature cycling — so cartridges wear faster.

For single-handle kitchen faucets (the most common type), the cartridge controls both temperature and flow. When it wears, it no longer seals completely in the off position, and water drips through.

Repair: replace the cartridge. The specific cartridge depends on the faucet brand and model:
– Moen: 1225, 1225B, or 1200 are the most common kitchen cartridges — identifiable by model number on the faucet or the cartridge body
– Delta: Uses a ball mechanism rather than a cartridge — buy a Delta repair kit with ball, springs, and seats
– Kohler: Ceramic disc cartridges, model-specific
– Pfister: Cartridge-type, model-specific

For a step-by-step cartridge replacement guide, see our faucet cartridge replacement article.

How Much to Fix a Leaking Kitchen Faucet?

DIY cost (Seattle 2026):
– O-ring kit: $5–$15
– Replacement cartridge: $10–$40 (brand-specific)
– Delta ball repair kit: $12–$20
– New supply lines (if needed): $8–$15 each

Plumber cost (Seattle 2026):
– Service call / first hour: $95–$175
– Cartridge replacement: $125–$225 total
– O-ring replacement: $125–$200 total
– Full faucet replacement (if repair not viable): $200–$450 installed

Most kitchen faucet leaks are resolved in one plumber visit. If the faucet is an unusual brand or the cartridge is discontinued, a second visit may be needed to source parts.

Use the cost estimator for a current estimate based on your repair type.

Kitchen Faucet Leaking Under the Sink — Causes

Under-sink leaks from a kitchen faucet typically come from one of three sources:

1. Loose supply line connection — the braided hose connecting the shutoff valve to the faucet inlet has a threaded nut that can loosen over time. Hand-tighten the nut first; if still leaking, replace the supply line.
2. Cracked or failing supply line — braided stainless supply lines have a rubber interior that can crack after 8–10 years. A failing line often shows as a slow seep at the braided exterior before it fails completely.
3. Loose faucet mounting nut — the nut that holds the faucet to the sink deck from below can loosen, allowing water from the base to travel down the faucet body and drip below the sink

Inspect under the sink with a flashlight while someone runs the faucet. Trace any moisture to its source before replacing parts. A drop of water at the supply line nut may just need tightening; a wet area on the entire underside of the sink deck may point to the mounting nut.

WARNING: Braided stainless supply lines that show any exterior corrosion, kinking, or bubbling should be replaced immediately. A supply line failure under the sink can discharge several gallons per minute — enough to flood the cabinet, damage the floor, and spread to adjacent cabinetry in minutes. Supply lines cost $8–$15 and are a cheap form of insurance.

How to Tighten a Loose Kitchen Faucet Handle

A loose handle that wobbles or rotates more than it should typically has a loose set screw or retaining nut.

For most single-handle faucets:
1. Look for a decorative cap on top of or behind the handle — pop it off with a flathead screwdriver
2. The set screw underneath is usually a 3/32″ or 1/8″ hex (Allen) screw
3. Tighten with the appropriate Allen key — clockwise until snug
4. Replace the cap

For two-handle faucets:
1. Each handle has its own set screw under a cap
2. Same process — find the cap, access the screw, tighten

If the handle continues to feel loose after tightening the set screw, the cartridge itself may have worn threads or the handle-to-cartridge connection is stripped. At that point, replacing the cartridge (and handle if the connection is stripped) is the correct fix.

Kitchen Faucet Leaking Around the Handle — Not the Spout

A leak that appears around the handle — not from the spout tip — is an O-ring or packing issue at the handle’s connection to the faucet body. Water is migrating up the stem and around the handle seal.

The fix depends on faucet type:
– Compression faucets: Replace the packing washer or O-ring around the stem
– Cartridge faucets: Replace the O-rings on the cartridge body — these are separate from the main sealing surfaces
– Ball faucets: Replace the O-rings on the ball housing

In all cases, shut off the supply valves, remove the handle, and inspect the O-rings visible at the stem or cartridge connection. These are usually available in a kit for $5–$10. See our faucet O-ring and washer replacement guide for the detailed process.

Is It Cheaper to Fix or Replace a Leaky Kitchen Faucet?

Fix it if:
– The faucet is under 15 years old
– The brand is a major manufacturer with available parts
– Only one part needs replacement (cartridge, O-ring, or supply line)
– The faucet body is in good condition (no cracks, corrosion, or finish damage)

Replace it if:
– The faucet is over 20 years old and parts are discontinued
– Multiple components have failed simultaneously
– The repair cost (plumber + parts) approaches $200–$300 — a new mid-range faucet installed costs $200–$400 total
– The homeowner wants to upgrade the style anyway

The tipping point in Seattle: if a plumber quotes over $175 for a repair and the faucet is over 15 years old, get a replacement quote alongside the repair quote. A new Delta or Moen faucet (quality brands with good warranty support) runs $80–$200 for the fixture; a plumber charges $100–$200 to swap it.

Leaky Kitchen Faucet Getting Worse — How Urgent Is It?

A leak that’s visibly worsening warrants prompt attention but is rarely an emergency. The timeline for action depends on where it’s leaking:

• Spout drip getting faster: Schedule repair within 1–2 weeks. Water waste and potential valve seat damage are the concerns.
• Base leak growing larger: Schedule within a few days. Water at the base can migrate under the sink and damage the cabinet floor and substrate.
• Under-sink supply line seeping: Address the same week. A slow seep can accelerate without warning to a full failure.
• Under-sink supply line spraying: This is urgent — shut off the supply valves immediately and call a plumber same day.

Kitchen Faucet Still Leaking After I Replaced the Cartridge — Why?

The most common reasons a spout still drips after a new cartridge:

1. Damaged valve seat — the brass seat inside the faucet body that the cartridge seals against is pitted or corroded. A new cartridge can’t seal against a damaged seat. A plumber can resurface or replace the seat.
2. Wrong cartridge — double-check the part number. Even within the same brand, cartridge models vary. A Moen 1225 and 1225B are interchangeable; a 1225 and 1200 are not.
3. Cartridge installed in wrong orientation — some cartridges are directional. If hot and cold are reversed or the faucet doesn’t shut off completely, rotate the cartridge 180° and reinstall.
4. O-rings on the cartridge body not replaced — the cartridge’s internal seal is new, but the O-rings around the cartridge body are worn and allowing water to bypass

If the cartridge replacement didn’t stop the drip, take the faucet apart again and look at the valve seat with a flashlight. A pitted or visibly rough seat is the answer.

FAQ

Q: Why does my kitchen faucet drip only sometimes?
A: Intermittent dripping usually points to a cartridge that seals adequately at low temperatures but fails as it expands with heat — or vice versa. It can also occur when water pressure is higher than usual (overnight, early morning). Either way, the cartridge is the likely cause and replacement will resolve it.

Q: How long should a kitchen faucet cartridge last?
A: 8–15 years under typical kitchen use. Tacoma and harder-water areas of WA see shorter lifespans due to mineral accumulation on the cartridge sealing surfaces. Seattle’s softer water is gentler on cartridges.

Q: Can a leaky kitchen faucet cause mold under the sink?
A: Yes — if the leak is from the base or under the sink and goes unaddressed for weeks or months, moisture accumulates in the cabinet and promotes mold growth on the cabinet floor and back panel. Fix base and under-sink leaks within a few days; they’re not emergencies but they’re not ignore-indefinitely situations.

Q: How much water does a leaky kitchen faucet waste per month?
A: A one-drip-per-second kitchen faucet wastes approximately 90 gallons per month. At SPU’s current rates, that’s less than $1 per month in water cost — but a faster drip or trickle adds up more meaningfully. The repair cost is almost always recovered in water savings within a year.

Q: Should I fix a leaky kitchen faucet myself or call a plumber?
A: Most kitchen faucet leaks are DIY-accessible if you’re comfortable shutting off supply valves and handling basic hand tools. The exception: valve seat damage, which requires specialized tools (seat wrench) and more experience to assess correctly. If you’ve replaced the cartridge and it’s still dripping, that’s when to call a plumber.