Kitchen Faucet Leaking at Base? 5 Causes & How to Fix

If you're seeing water pooling around the base of your kitchen faucet whenever you turn on the water, you're dealing with one of the most common and fixable plumbing issues in the home. That puddle forming where your faucet meets the countertop or sink deck isn't just annoying; it can damage your counters, cabinets, and even the flooring below if left unaddressed.

After diagnosing thousands of kitchen faucet leaks since 1923, our licensed plumbers know exactly what causes water to leak from the faucet base and which fixes work best for each situation. Here's what you need to know to identify, repair, and prevent base leaks in your kitchen faucet.

Why Is My Kitchen Faucet Leaking at the Base?

A kitchen faucet leaking at the base, where the faucet body meets the sink deck, countertop, or mounting plate, happens when water escapes from internal seals and flows down the outside of the faucet rather than through the spout. This is different from a dripping faucet (water coming from the spout) or a handle leak (water around the handle area).

The key pattern to identify a base leak:

• Water appears around the faucet base only when the faucet is running
• The puddle forms quickly after turning on the water
• More water = higher water flow or pressure
• Water seeps down between the faucet and the counter/sink
• You may see water dripping from underneath the sink onto the cabinet floor

If your faucet drips when it's turned off, or if water comes from the handle area, you have a different issue. A base leak occurs when water flows and escapes from failed seals inside the faucet body.

5 Causes of Kitchen Faucet Base Leaks (Ranked by Frequency)

Based on hundreds of kitchen faucet repairs we've performed throughout North Metro Atlanta, here are the five most common causes of base leaks, ranked from most to least frequent:

1. Worn or Damaged O-Rings (55% of Cases)

What's happening: O-rings are small rubber gaskets that create watertight seals inside a faucet, especially where the spout meets the faucet body. They sit in grooves and compress to stop leaks. Over time, they deteriorate due to wear, mineral buildup, temperature changes, and chemical exposure.

Why O-rings fail:

• Age and wear: Typically last 5-8 years before becoming brittle or cracked

• Hard water: Mineral deposits harden the rubber and reduce elasticity

• Chemical exposure: Harsh cleaners degrade rubber

• Temperature stress: Hot water causes repeated expansion and contraction

• Lack of lubrication: Dry O-rings crack faster without plumber's grease

Common O-ring locations:

• Spout base: Where the spout meets the faucet body (most common leak point)

• Cartridge area: Around the internal cartridge

• Handle assembly: Under single-lever or pull-down faucet handles

Solution: Remove the spout by pulling it upward (most modern faucets) or unscrewing it (older models). Locate the O-rings in the grooves, replace them with the correct size, and lubricate with plumber's grease before reassembly.

If you're unsure about disassembly or sizing, a licensed plumber can replace the O-rings quickly and restore proper sealing.

2. Loose or Corroded Mounting Hardware (25% of Cases)

3. Faulty or Worn Cartridge (12% of Cases)

What's happening: The cartridge is the internal valve that controls water flow and temperature. In single-handle faucets, it's a ceramic disc, compression, or ball-type cartridge. When it wears out or cracks, water leaks into the faucet body and exits at the base rather than the spout.

Why cartridges fail:

• Sediment damage: Minerals and debris scratch sealing surfaces

• Normal wear: Typical lifespan is 10-20 years, depending on water quality

• Manufacturing defects: Some designs fail early

• Water hammer: Sudden pressure spikes crack internal parts

• Freezing: Rare, but it can split the cartridge

Common cartridge types by brand:

• Moen: 1225 (most common), 1200, 1248, 1255

• Delta: RP19804 (Monitor), RP50587 (single-handle), RP46463

• Kohler: GP77006, GP500520 ceramic disc

• Pfister: 974 (most common), 910, 922

Solution: Identify your faucet brand and model (often stamped on the spout or listed in original paperwork). Buy the correct replacement cartridge. Shut off the water, remove the handle and trim, unscrew the retaining nut, pull the old cartridge, install the new one in the correct orientation, and reassemble.

4. Deteriorated Faucet Base Gasket or Putty (5% of Cases)

What's happening: A watertight seal between the faucet base and the sink or countertop, made with a rubber gasket, plumber's putty, or silicone, prevents water from entering the cabinet below. When this seal fails, water bypasses the faucet internals and leaks around the base.

Why base seals fail:

• Age: Rubber gaskets harden and crack after 10-15 years

• Improper installation: Putty used where silicone is required, or vice versa

• Chemical damage: Acidic or abrasive cleaners degrade seals

• Heat exposure: Dishwasher steam and hot water accelerate breakdown

• Movement: Loose mounting hardware breaks the seal

Granite and solid-surface countertops: These usually use silicone rather than gaskets. Failed silicone appears brittle, discolored, or separated from the base.

Solution: Shut off water and disconnect supply lines. Remove the faucet by loosening the mounting hardware from below. Clean all old gasket material, putty, or silicone from the faucet base and sink or countertop using a plastic scraper and degreaser. Install a new gasket or apply fresh plumber's putty or silicone, then reinstall and properly tighten the mounting hardware.

This repair requires full faucet removal. A plumber can reseal and reinstall the faucet correctly to prevent repeat leaks.

5. Cracked Faucet Body (3% of Cases)

How to Diagnose Which Cause You Have

Before attempting any repair, follow this diagnostic process to identify the most likely cause:

Step 1: Observe the leak pattern

• Does the leak occur only when water is running? → Worn O-rings or cartridge
• Does the faucet wobble or feel loose? → Loose mounting hardware
• Is the leak worse with hot water? → O-ring failure (heat expands failed seals)
• Very large leak volume relative to water flow? → Failed base gasket/seal

Step 2: Check under the sink

• Use a flashlight to examine mounting hardware
• Try to wiggle the mounting nut. If it moves easily, it's loose
• Look for corrosion (white or green deposits) on nuts and bolts
• Check for water staining on the underside of the counter

Step 3: Test the handle operation

• Does the handle move smoothly, or does it feel stiff/crunchy? → Cartridge issue
• Do you hear grinding sounds? → Cartridge failure
• Is temperature control difficult? → Cartridge worn out

Step 4: Inspect the visible faucet

• Look for visible cracks in the faucet body
• Check for gaps between the faucet base and counter
• Examine the condition of any visible gasket or sealant
• Note faucet age (if known)

The Bottom Line on Kitchen Faucet Base Leaks

If your kitchen faucet is leaking at the base, you're most likely dealing with worn O-rings (55% of cases) or loose mounting hardware (25% of cases). Both are relatively straightforward repairs that can be completed in 30-60 minutes with basic tools and cost $5-20 for DIY repairs.

However, correctly identifying the cause is critical. Replacing O-rings when the cartridge is actually bad, or tightening mounting hardware when the base gasket has failed, wastes time and money without solving the problem. If you're unsure of the cause or have attempted a repair that didn't work, a professional diagnosis saves you from buying the wrong parts and ensures a permanent fix.

Need help fixing your leaking kitchen faucet? Our licensed plumbers can diagnose the exact cause, make repairs with quality parts, and prevent future leaks. Contact us for professional faucet repair services in Cumming, Alpharetta, Roswell, and North Metro Atlanta.