A kitchen sink faucet leaks due to worn components, mineral buildup, or damaged seals. Common causes include degraded O-rings, loose connections, or a malfunctioning cartridge. Addressing these issues promptly prevents water waste and ensures optimal performance.

The primary reasons for a leaking kitchen faucet stem from wear and tear on internal components. Over time, the O-rings, seals, or gaskets—critical for sealing the faucet’s valve stem and handle—can degrade due to constant water exposure and temperature fluctuations. According to the National Association of Home Builders (NAHB), approximately 40% of faucet leaks are caused by worn O-rings or seals. These components, typically made of rubber or synthetic materials, harden or crack, allowing water to escape.

Mineral buildup from hard water is another frequent culprit. Hard water contains calcium and magnesium ions that deposit on the faucet’s aerator, a mesh screen that mixes air with water. When the aerator becomes clogged, water flow is restricted, increasing pressure on the valve seat and causing leaks. The Environmental Protection Agency (EPA) reports that 85% of U.S. households face hard water, with clogged aerators contributing to 20% of all kitchen faucet leaks.

Additionally, a damaged cartridge—common in singlehandled faucets—can lead to leaks. Cartridges house the valve mechanism and may fail due to corrosion or physical damage. A 2021 HomeAdvisor study found that 35% of faucet repairs involve cartridge replacement, often requiring professional tools.

Lastly, loose pipe connections or a failing water supply valve can cause leaks. According to the NAHB, improper installation or aging pipes account for 15% of leaks. Regular maintenance, such as replacing O-rings, cleaning aerators, and inspecting connections, can mitigate these issues. For severe leaks, consulting a licensed plumber is recommended to avoid property damage. Addressing these factors early saves homeowners an average of $150 annually in water waste and repair costs, as noted by the EPA.