How to Replace a Kitchen Sink
Updated February 20, 2026
Remove an old kitchen sink and install a new one -- drop-in or undermount. Covers disconnecting plumbing, cutting countertop openings, and sealing for a watertight fit.
Overview
Replacing a kitchen sink is a moderate DIY job that most homeowners can handle in an afternoon. The plumbing is straightforward -- disconnect drain, disconnect supply lines, swap the sink, reconnect. The tricky part depends on the mount type. Drop-in (top-mount) sinks are easiest: they sit in the existing cutout with a rim that overlaps the countertop. Undermount sinks require support clips underneath and a clean seal to the countertop underside. If your new sink fits the existing cutout, the job is much simpler. If the cutout needs enlarging, plan for extra time and the right cutting tools.
What You'll Need
Safety First
- Turn off water supply and disconnect the garbage disposal (if present) before removing the old sink. Unplug the disposal or turn off its breaker.
- Kitchen sinks are heavy -- stainless steel is 15-25 lbs, cast iron can be 50+ lbs. Have a helper for lifting, especially undermount installations.
Step-by-Step Instructions
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Disconnect All Plumbing
Turn off hot and cold shut-off valves. Disconnect supply lines from the faucet or valves. Remove the P-trap -- bucket underneath to catch water. If you have a garbage disposal, unplug it, disconnect the drain, and remove it from the sink flange (twist the mounting ring). Remove the faucet if you are reusing it on the new sink, or leave it if replacing both.
Tip: Take photos of every connection before disconnecting. Label hot and cold supply lines with tape if they look similar. -
Remove the Old Sink
Drop-in sinks: cut the caulk seal around the rim with a utility knife. Remove any clips underneath. Push up from below or pry gently from above. Lift out. Undermount sinks: support the sink from below (have a helper or use a 2x4 brace), then remove the mounting clips from the underside of the countertop. Lower the sink carefully. Scrape old caulk and adhesive from the countertop with a putty knife.
Tip: If the old caulk is silicone and stubborn, use a caulk remover to soften it before scraping. Clean the surface completely -- new caulk will not adhere to old residue. -
Check the Cutout and Dry-Fit
Place the new sink upside down on the countertop and trace its outline (drop-in) or check the cutout dimensions against the sink body (undermount). Most standard sinks fit standard cutouts, but verify. If the cutout is too small, mark the new cut line and enlarge with a jigsaw (laminate or solid surface) or call a fabricator (granite or quartz). If the cutout is too large, you need a bigger sink or a countertop repair.
Tip: For drop-in sinks, the cutout should be about 1/2 inch smaller than the sink rim on all sides so the rim has a solid surface to rest on. -
Install the Faucet and Drain Hardware
Much easier to install the faucet, drain strainers, and any accessories (soap dispenser, sprayer) while the sink is on the countertop upside down or on a workbench -- before setting it in the cutout. Follow manufacturer instructions for each component. Tighten drain strainer locknut from below. Plumber's putty under the strainer flange for a watertight seal.
Tip: Installing hardware on a bench is 10 times easier than reaching up into the cabinet after the sink is in place. Do as much pre-assembly as possible. -
Set the Sink
Drop-in: apply a continuous bead of silicone caulk around the cutout edge (or use the included foam gasket). Lower the sink into the cutout, pressing down evenly. Attach any mounting clips from below. Wipe excess caulk. Undermount: apply silicone to the countertop underside around the cutout. Lift the sink into position from below (helper needed), install mounting clips, and tighten evenly. Support from below until the silicone sets.
Tip: For undermount on granite or quartz, use a two-part epoxy for the clips instead of relying only on silicone. The epoxy bonds the clip to the stone permanently. -
Reconnect Plumbing and Test
Reconnect the P-trap to the drain tailpiece and wall stub-out. Reconnect supply lines to the shut-off valves. Reinstall the garbage disposal if applicable (mount to the new drain flange, reconnect drain line, plug in). Turn on water slowly. Check every connection for leaks. Run both hot and cold. Fill the sink and drain it to test the drain and P-trap under full flow. Run the disposal.
Tip: Let silicone caulk cure for 24 hours before heavy use. Light water testing is fine, but do not fill the sink to the brim and let it sit until the caulk has fully set.
Pro Tips
- Buy the sink and faucet at the same time. Verify the faucet hole count and spacing match the sink before you start the project.
- If replacing a double-bowl with a single-bowl (or vice versa), the drain plumbing layout will change. Plan the new drain routing before you start.
- Stainless steel sinks with sound-deadening pads on the underside are worth the premium. Thin gauge steel without pads is noisy and tinny.
- A sink that is 1 inch deeper than your old one may require lowering the P-trap or adjusting the drain height. Check clearance before committing.
- If you are also replacing the countertop, have the new countertop fabricated with the correct cutout for your new sink. Much easier than cutting on-site.
When to Call a Pro
Call a plumber if the countertop cutout needs enlarging on granite, quartz, or marble (requires professional fabrication), if the drain plumbing needs significant rerouting, if the shut-off valves need replacement, or if you are installing an undermount on stone and need professional epoxy and clip work for a secure mount.