How to Install a New Kitchen Sink

Installing a new kitchen sink is one of those projects that looks more intimidating than it actually is. The sink itself—whether it's stainless steel, cast iron, or composite—is just a basin. The real work is disconnecting the old one cleanly, making sure the new one sits level and sealed properly, and reconnecting water and waste without leaks. You'll need a bucket, a wrench, and willingness to get under the cabinet. If you've ever changed a faucet or replaced a toilet, you can install a sink. The difference between a sloppy installation and a tight one comes down to taking time with the seal and not forcing the connections.

1. Clear the Cabinet and Kill the Flow. Locate your main water shutoff valve and turn it clockwise until the water stops. Open the faucet at your kitchen sink to release any remaining pressure. Remove everything from under the sink—cleaning supplies, containers, trash. You need clear access to the drain trap and the water supply lines.
2. Free the Supply Lines. Use an adjustable wrench to loosen the compression nuts connecting the hot and cold water supply lines to the faucet tailpieces. Turn counterclockwise. Once loose enough to hand-turn, unscrew them the rest of the way and pull the supply lines free. If the lines are stiff or stuck, apply penetrating oil and wait five minutes.
3. Remove the Trap System. Place your bucket underneath. Loosen the slip nut connecting the P-trap to the vertical tailpiece coming from the sink. Once it's hand-tight, unscrew it fully and lower the trap. Then loosen the slip nut where the trap connects to the wall drain stub and remove the trap entirely. You may need to loosen the tailpiece locknut under the sink to free up the tailpiece itself.
4. Unbolt and Lift Out. Most sinks are held down by clips or brackets bolted to the underside of the countertop. Reach underneath and locate these bolts. Use an adjustable wrench or socket wrench to loosen and remove them—typically four to six bolts around the perimeter. Once all bolts are out, push the old sink up from below. It should lift free. If it's stuck, run a putty knife around the edge to break the seal.
5. Seal and Set Level. Clean out the sink opening completely. Remove old putty, sealant, or debris. Dry it thoroughly. Apply a bead of plumber's putty or silicone caulk around the underside rim of the new sink—not on top of the countertop, but on the sink itself where it will contact the counter. Lower the sink into the opening carefully, centering it. Check that it sits level with a torpedo level. From underneath, hand-tighten all mounting clips or bolts, then tighten them evenly in a crisscross pattern so the sink settles evenly. Wipe away excess putty from the top.
6. Reattach the Drain. Insert the drain tailpiece through the hole in the sink (it comes with a rubber washer and locknut). Hand-tighten the locknut from below. Connect the P-trap back to the tailpiece using the slip nut you removed earlier. Tighten snug with a wrench—hand-tight plus a quarter turn. Then connect the trap to the wall drain stub the same way. Don't overtighten; these nuts will strip.
7. Restore the Water Lines. Thread the hot water supply line onto the hot water inlet at the faucet body (usually on the right when facing the sink). Hand-tighten first, then use your wrench for a half turn more. Repeat with the cold water line on the left inlet. Don't over-tighten compression fittings; you only need enough pressure to make a watertight seal.
8. Hunt for Leaks. Turn the main water valve on slowly. Let the faucet run for 30 seconds. Check all three connection points—both supply line nuts and the P-trap slip nuts—for drips or moisture. Let the sink fill and drain. If you see a slow drip at any nut, tighten it slightly. If water pooled under the sink but the connections are dry, the leak is coming from the sink itself or its seal; you may need to reseal it or contact the manufacturer.