How to Install Vanity Sink | Step-By-Step Bathroom Project

Installing a vanity sink takes one weekend, basic plumbing tools, and careful attention to leveling and sealing for a leak-free finish.

Whether you’re replacing a dated bathroom fixture or finishing a remodel, mounting a new vanity sink is a project most homeowners can handle. The process covers shutting off water, removing the old unit, setting the new vanity, and reconnecting the plumbing. Before you start, measure your space and confirm your new fixture matches the existing rough-in. If you’re still shopping for the right size, our tested roundup of the best 24-inch vanity sink options can help narrow the choice.

Tools and Materials You’ll Need

Having everything within reach before you start prevents mid-project trips to the hardware store. Most of these tools are standard household items, but the basin wrench and plumber’s putty are worth buying if you don’t own them.

• Adjustable wrench and basin wrench
• Screwdriver (Phillips and flathead)
• Level, tape measure, and pencil
• Stud finder and drill with bits
• Bucket or pan for water catch
• Plumber’s putty or silicone caulk
• Shims, wall anchors, and screws
• Safety glasses and work gloves

Check the manufacturer’s instructions that ship with your vanity. Both Home Depot and Lowe’s emphasize test-fitting parts before final assembly, and Kohler’s installation guidance recommends lifting the vanity top and sink with assistance — these units are heavier than they look.

How to Remove the Old Vanity Safely

Start by shutting off the water supply valves beneath the sink, then open the faucet to relieve pressure in the lines. This step prevents an unexpected spray when you disconnect the supply tubes.

Place a bucket or pan under the P-trap before loosening its nuts, since standing water will drain out. Loosen the slip nuts on both ends of the trap with your adjustable wrench, then remove the curved section. Disconnect the supply lines from the shutoff valves, and if your old unit is caulked to the wall, run a utility knife along the seam to break the seal. Remove the sink and vanity as a unit if possible, or detach the top first for easier handling.

Lowe’s recommends removing the doors and drawers from the old vanity before pulling it away — this reduces weight and prevents them from swinging open and scratching the wall. Once the unit is free, inspect the wall for water damage or mold. Now is the time to repair any issues you find.

Installing the New Vanity and Sink

Position the new vanity against the wall and check it with a level in both directions. Use shims under the base to correct any floor slope, then mark the mounting hole locations through the back panel onto the wall.

Use a stud finder to locate the framing behind your marks. Screw the vanity to the wall studs with appropriate screws; if the holes don’t align with studs, Lowe’s says to use wall anchors rated for the vanity’s weight. For installations where the studs miss the mounting holes entirely, Home Depot recommends adding sufficient wall supports behind the finished wall before mounting. Leave the doors and drawers off until the unit is secured, which makes the interior accessible for plumbing work.

Check that the shutoff valves and drain outlet remain accessible through the vanity’s back panel or floor opening. Drill plumbing access holes slightly larger than the pipes so nothing binds or rubs against the cabinet walls.

Setting the Sink Top

With the vanity secured, you’ll install the sink top. For a drop-in or vanity-top sink, test-fit the bowl into the cutout first, then attach the mounting clips from underneath per the manufacturer’s pattern. Home Depot advises assembling the faucet and drain before permanently setting the sink — this saves you from leaning over the bowl to reach awkward fittings.

Insert the faucet through its mounting holes with the plastic gasket in place, then hand-tighten the retaining nut underneath before final tightening with your basin wrench. Connect the supply lines to the faucet tails using your adjustable wrench, being careful not to overtighten. Apply a bead of plumber’s putty around the drain flange, insert it through the sink hole, and secure the drain assembly from below.

Lift the sink top into position with assistance if needed, set it onto the vanity cabinet, and complete the drain connections. Add a bead of caulk where the sink meets the wall to prevent water from seeping behind the unit, but avoid overtightening any fastener — Home Depot warns that sinks can chip or crack under excessive force.

Undermount and Vessel Sink Variations

An undermount sink attaches beneath the countertop rather than sitting on top. Position the sink over the cutout, apply silicone to the sink’s upper edge, and press it into place using alignment marks you made earlier. Let the silicone cure per the manufacturer’s time recommendation, then install the undermount clips — hand-tight only, since the clips are meant to hold the sink in place while the adhesive cures, not to crush it against the countertop.

For a vessel sink that sits above the counter, Lowe’s says to apply clear silicone caulk around the bottom rim of the bowl, set it over the mounting hole, and assemble the drain without overtightening. If your bowl lacks a flat bottom, use the mounting ring included with the faucet kit to create a stable seal.

Reconnecting the Plumbing and Finishing Up

Reconnect the supply lines to the shutoff valves, tighten them snugly, and reinstall the P-trap between the drain tailpiece and the wall stub-out. Turn the water supply back on slowly and check every joint for drips — wrap a dry paper towel around each connection to catch slow leaks you might miss visually. Run water through both the hot and cold taps, then open the drain and watch for seepage around the trap and drain flange.

Once you’ve confirmed there are no leaks, reinstall the vanity doors and drawers. Apply a final bead of caulk along the top edge where the sink meets the wall, then smooth it with a wet finger for a clean finish. Let all sealants cure fully before using the sink normally.

The project is complete when the vanity is level, the sink is sealed, and the plumbing holds water without dripping. If you’re installing this on a tighter budget or a smaller bathroom layout, keep the 24-inch sizing in mind — the top-rated 24-inch vanity sinks we tested offer solid options that fit compact spaces while still providing storage.