Why Is My Sink Faucet Dripping?

Your sink faucet is likely dripping because an internal seal—such as the cartridge, O-ring, or valve seat—has worn out or become clogged with mineral buildup. These small components are responsible for creating a watertight seal, and when they fail, water continues to escape even after the faucet is turned off.

Common Causes of a Dripping Sink Faucet

1. Worn Cartridges or Ceramic Discs

Most modern faucets use cartridges or ceramic discs to control water flow. When these parts degrade, water slips through the mechanism and drips from the spout.

2. Damaged O-Rings

If water leaks from the base of the handle or around the faucet body, a cracked or dried-out O-ring is the likely culprit. These rubber seals wear down naturally over time.

3. Loose or Worn Internal Parts

Over years of use, screws, retaining nuts, and seals inside the faucet can loosen. This prevents the faucet from holding back water pressure properly, resulting in drips.

4. Mineral Buildup

Hard water deposits can interfere with the faucet’s internal sealing surfaces. When minerals accumulate, they prevent parts from closing fully and create persistent leaks.

5. Corroded Valve Seats

Older faucets often develop corrosion where the spout connects to the faucet body. This deteriorated surface prevents washers from sealing tightly, leading to continuous dripping.

How to Know When to Call a Plumber

If replacing basic components—like the cartridge or O-rings—doesn’t stop the drip, the faucet may have deeper corrosion or pressure issues. A licensed plumber can diagnose the cause quickly and prevent further water waste.