Begin by turning off the water supply to the sink using the hot and cold shutoff valves located beneath it. If they are inoperable, you must shut off the main water supply to the house. Place a bucket under the P-trap to catch residual water. Use an adjustable wrench to disconnect the hot and cold water supply lines from the valves. Next, loosen the slip nuts on the P-trap and remove it. If replacing a vanity, use a utility knife to score the caulk seal along the backsplash and sides where it meets the wall. Disconnect any clips holding the old sink to the countertop, then carefully lift the old sink and vanity out of the bathroom. Clean the area thoroughly.

A pedestal sink requires solid backing in the wall for support. Use a stud finder to locate the studs on either side of your drain pipe. Use a level and pencil to draw a rectangle on the wall where the sink will be mounted. The top of this rectangle should be at your desired sink rim height (typically 34-36 inches). Carefully cut out this section of drywall using a drywall saw. Measure the distance between the studs and cut a piece of 2x8 lumber to fit snugly. Position this blocking horizontally between the studs, centered at the height where the sink's mounting holes will be. Secure the blocking by driving wood screws through the studs and into the ends of the 2x8 block.

It is much easier to install the faucet and drain before the sink is mounted. Place the sink basin upside down on a soft, protected surface like a towel or piece of cardboard. Following the manufacturer's instructions, insert the faucet through the mounting holes on the sink deck. From the underside, attach and tighten the mounting nuts. A basin wrench can be very helpful for tightening these nuts in the tight space. For the drain, apply a rope of plumber's putty around the underside of the drain flange. Insert the drain body through the drain hole from the top of the sink. From underneath, install the gasket and tighten the large locknut to secure it. Do not overtighten. Connect the pop-up drain linkage as per the instructions.

After patching the drywall (a full finish is not necessary behind the sink), perform a dry fit. Place the pedestal base where it will be installed. With a helper, carefully set the sink basin on top of the pedestal. Push the entire assembly against the wall, ensuring the sink basin is centered over the pedestal and is level both front-to-back and side-to-side. Use a pencil to trace the outline of the pedestal base on the floor. Then, reach behind the sink and mark the locations for the mounting bolts on the wall through the holes in the back of the sink. Carefully remove the sink and pedestal.

At the locations you marked on the wall for the sink basin, drill pilot holes into the wood blocking. The drill bit should be slightly smaller in diameter than the lag bolts that came with your sink. Move the pedestal into its final position, aligning it with the outline you traced on the floor. With your helper, lift the sink basin and carefully guide it onto the top of the pedestal, aligning the mounting holes with the pilot holes you drilled in the wall. Insert the lag bolts with their washers through the mounting holes. Use a socket wrench to tighten the bolts, alternating between them to apply even pressure. Tighten until the sink is snug against the wall but do not overtighten.

Now, connect the plumbing. Attach the flexible water supply lines from the faucet inlets down to the corresponding hot and cold shutoff valves. Hand-tighten the nuts, then use a wrench to give them an additional quarter- to half-turn. Do not overtighten. Next, assemble the P-trap. Connect the tailpiece extension to the bottom of the sink's drain assembly if needed. Attach the P-trap to the tailpiece and the drain stub-out in the wall. The slip nuts on the P-trap are designed to be hand-tightened only. Ensure all gaskets are properly seated before tightening.

With all connections made, it's time to test your work. Place a dry rag or paper towel under each connection point to make leaks easier to spot. Turn the shutoff valves on slowly, starting with cold then hot. Carefully inspect the supply line connections at both the valve and the faucet for any drips. Turn the faucet on and let the water run. Check all the P-trap connections for leaks. Fill the sink basin completely with water, then release the pop-up drain. Watch the entire drain assembly for leaks as the large volume of water flows through. If you find a small leak, try tightening the connection slightly. Apply a thin, neat bead of kitchen and bath silicone caulk around the base of the pedestal where it meets the floor, and also along the back edge of the sink where it meets the wall. Smooth the bead with a wet finger.