How to Install a Bathroom Vanity Plumbing System

Vanity installation is the point where a bathroom renovation transforms from a framing project into a functional space. The goal is a leak-free connection that tucks neatly into the back of your cabinet, leaving you with reliable water flow and efficient drainage without cluttering your storage area. Success in this project hinges on dry-fitting your components before reaching for the plumber's tape or sealant. Once you verify that the pipes align correctly with your wall-side stubs, the actual connection process becomes a straightforward matter of tightening fittings until they are snug and secure.

Seal and Thread Shut-Offs. Wrap the threads of your hot and cold wall stubs with PTFE tape in a clockwise direction. Thread your 1/4-turn shut-off valves onto the pipes, tightening them with a wrench until they are firmly seated and oriented toward your faucet hoses.
Link Supply Lines. Connect the flexible supply hoses from your faucet to the top outlets of the shut-off valves. Tighten the compression nuts by hand, then add a final half-turn with an adjustable wrench to ensure a watertight seal.
Secure the Drain Core. Apply a thin bead of plumber's putty around the underside of the drain flange and press it into the sink basin. Secure the drain assembly from underneath the basin using the included rubber washer and lock nut.
Bridge Drain to Wall. Slide the slip joint nuts and washers onto your drain tailpiece and the wall-side stub pipe. Connect the P-trap components to bridge the gap between the sink drain and the wall drain pipe, tightening all nuts by hand.
Verify Zero Leaks. Slowly turn on your shut-off valves and inspect every connection for moisture. Fill the sink basin and release the water all at once to put pressure on the drain seals and check for drips.
Waterproof the Seams. Apply a clean bead of silicone caulk along the junction where the vanity backboard meets the wall. Smooth the bead with a damp finger to create a professional, water-resistant finish.