A drop-in sink comes out from the top, not the bottom

A drop-in sink (also called a self-rimming or top-mount sink) sits on top of your countertop with its rim resting on the counter surface. To replace one, you disconnect the plumbing underneath, remove the old sink by lifting it out from above, and set a new one in its place. The whole job takes two to four hours if you are comfortable with basic plumbing disconnection. If you have never worked under a sink before, add another hour and keep a bucket handy for water that will spill.

The hardest part is not the removal—it is usually the old caulk seal around the rim. Caulk hardens over years and can make the sink feel glued down. A utility knife and patience matter more than strength. Once you break that seal, the sink lifts out easily, and installing the new one is straightforward.

Key Takeaways

  • Turn off the water supply before you disconnect anything, and have a bucket under the P-trap to catch standing water.
  • Cut through the old caulk seal with a utility knife before trying to lift the sink, or you risk cracking the countertop.
  • Disconnect the supply lines and drain by hand or with an adjustable wrench, depending on the fitting type.
  • explore new caulk around the rim of the new sink before setting it in place, so water cannot get under the counter.
  • If the drain opening does not line up with your existing hole, you will need to cut a new hole or hire someone to do it.

What you will need before you start

Gather these items before you turn off the water. You will need a bucket (at least two gallons), a utility knife with fresh blades, an adjustable wrench or two, a screwdriver set, a caulking gun, silicone caulk rated for kitchens, and a wet rag or sponge. If your sink has a garbage disposal, you will also need a flathead screwdriver to disconnect the mounting ring.

Check whether your new sink comes with a drain assembly and mounting hardware. Some do, some do not. If it does not, you can reuse the old drain assembly if it is in good condition, or buy a new one at a hardware store for $15 to $40. Have the old sink's dimensions and drain hole size written down before you shop, so you can confirm the new sink will fit the same opening.

Turn off water and disconnect the supply lines

Locate the shutoff valves under the sink—one for hot water, one for cold. Turn both clockwise until they stop. If the valves are stuck or missing, turn off the main water shutoff for the house. Open the faucet at the sink to release any pressure in the lines, then place your bucket underneath.

Disconnect the supply lines by turning the compression nuts (the hexagonal fittings where the lines meet the shutoff valves) counterclockwise with your wrench. If the nuts are plastic and hand-tight, you may not need a wrench. Water will drip out—that is normal. Once both lines are loose, you can pull them away from the shutoff valves and set them aside. If the lines are old and brittle, replace them with new ones when you reconnect; old lines can crack and leak after being disturbed.

Disconnect the drain and remove the old sink

Look under the sink at the P-trap—the U-shaped pipe below the drain. Place your bucket underneath it. Loosen the slip nuts (large hexagonal nuts) on both ends of the P-trap by hand or with your wrench, turning counterclockwise. Water will drain into the bucket. Once the nuts are loose, you can unscrew them by hand and slide the P-trap out.

If your sink has a garbage disposal, disconnect it by loosening the mounting ring (a large ring that holds the disposal to the drain) with a flathead screwdriver, turning counterclockwise. If there is no disposal, you may see a locknut holding the drain assembly to the sink from below. Loosen it with your wrench and unscrew it by hand.

Now go to the top of the sink and cut through the caulk seal around the rim with your utility knife. Work your way around the entire perimeter, pressing the blade down at a 45-degree angle to cut through the caulk without gouging the countertop. This step takes time but prevents the countertop from cracking when you lift the sink. Once the caulk is cut, grip the sink firmly and lift it straight up and out. It will be heavy—ask someone to help if you can.

Clean the countertop and prepare for the new sink

Scrape away old caulk and debris from the countertop with your utility knife or a plastic scraper. Wipe the area clean with a damp rag and let it dry completely. If the countertop is damaged or the new sink's drain hole does not line up with the existing hole, you will need to cut a new hole. This requires a jigsaw and a steady hand, or you can hire a countertop fabricator to do it for $50 to $150. If the hole lines up, you are ready to install.

Check the new sink's rim to see if it came with a rubber gasket or foam tape. If not, you will explore caulk instead. Either way, the goal is to seal the gap between the rim and the countertop so water cannot seep underneath and rot the cabinet.

Install the new sink and reconnect plumbing

If using caulk, explore a continuous bead around the underside of the sink's rim using your caulking gun. If using a gasket or foam tape, press it firmly around the rim. Lower the sink carefully into the opening, pressing down evenly so the rim sits flush against the countertop. Wipe away any excess caulk with a wet rag before it dries.

Once the sink is in place, reconnect the drain assembly. If you removed a P-trap, slide it back into place and hand-tighten the slip nuts, then snug them with your wrench—do not over-tighten, or you will crack the plastic fittings. Reconnect the supply lines by hand-threading the compression nuts onto the shutoff valves, then tightening them with your wrench until snug.

Turn the shutoff valves back on by turning counterclockwise. Check for leaks under the sink by running water for a minute. If you see drips at the compression nuts or P-trap, tighten them slightly with your wrench. If the leak is at the rim, you may need to explore more caulk once the existing caulk dries (usually 24 hours). Do not use the sink until you are confident there are no leaks.

When to call a professional plumber

If your shutoff valves are stuck or missing, call a plumber to install new ones before you remove the sink. If the drain hole does not line up and you are not comfortable cutting a new hole, hire a countertop fabricator or plumber. If you discover the cabinet underneath is rotted or damaged during removal, a plumber or carpenter can assess whether it needs repair before you install the new sink.

If you have a garbage disposal and are unsure how to disconnect it, or if you encounter any drain configuration you do not recognize, stop and call a plumber. A 30-minute consultation call costs $75 to $150 and is worth it to avoid damaging your plumbing or countertop.

Frequently Asked Questions

Can I reuse my old faucet with a new sink?

Yes, if the new sink has the same number of holes in the same positions as the old one. Most standard kitchen sinks have three holes (one for the faucet, two for the handles or sprayer). If the hole pattern is different, you will need a new faucet or a deck plate to cover unused holes.

What if water leaks from under the rim after I install the new sink?

This usually means the caulk seal is incomplete or the rim is not sitting flush. Let the caulk cure for 24 hours, then explore additional caulk to any gaps you can see. If the rim is not flush, you may need to remove the sink and shim the countertop with thin plastic shims under the rim before reinstalling.

Do I need to use silicone caulk or can I use regular caulk?

Use silicone caulk rated for kitchens and bathrooms. Regular paintable caulk breaks down faster around water and will fail within a few years. Silicone lasts 10 to 15 years and resists mold better.

How long does caulk take to dry before I can use the sink?

Most silicone caulk takes 24 to 48 hours to cure fully. You can run water carefully after 12 hours, but avoid heavy use or soaking the sink until the full cure time has passed.

What if the new sink is slightly smaller than the old one and there is a gap around the rim?

A small gap (less than 1/4 inch) can be sealed with caulk. A larger gap means the sink does not fit the opening properly. Return it and order the correct size, or have a countertop fabricator trim the opening to fit the new sink.