Step 5 · Clean and Inspect the Valve Seat

This is the step most people slow down on. Take it one move at a time — there’s no rush, and you can rewind the clip as many times as you need.

Before reinstalling the stem, look down into the empty faucet body to inspect the valve seat, which is the brass rim that the seat washer presses against. Mineral deposits or corrosion on this seat can cause a leak even with a new washer. Use a clean rag wrapped around a screwdriver to wipe the inside of the valve seat clean. If you feel nicks, pits, or roughness, you will need to smooth it. A specialized tool called a valve seat wrench or seat dresser is used for this. Insert the tool and give it a few gentle clockwise turns to lightly grind the seat down to a smooth, flat surface.