Cartridge Faucet

A cartridge faucet houses all its valve functions inside a single cylindrical or tapered cartridge that slides into the faucet body. Moving the handle up/down controls flow, and side-to-side (or rotating) adjusts the hot/cold mix. The cartridge contains grooves, ports, and a sealing mechanism that directs water without exposed washers or O-rings in the main cavity.

These are standard on most single-handle kitchen and bath faucets today. When one fails—drip, no hot water, or stuck handle—you swap the cartridge rather than rebuild individual stems. Moen, Delta, KWC, Kohler all use proprietary designs, so you need the right cartridge model. Many run $20–$60 and take minutes to replace if the customer didn't let it calcify shut.

Cartridges fail from debris, mineral buildup, and worn seals. A dripping cartridge faucet under warranty is usually a free swap; an older one past its life is cheaper to replace than fight corrosion inside the body. Always shut off and drain the line before pulling the handle dome or cap—pressure can surprise you.