What You'll Do to Replace Your Kitchen Sink

Replacing a kitchen sink means removing the old one from underneath the counter, disconnecting the plumbing, and installing a new sink in its place. The job takes two to four hours for a straightforward swap into an existing hole, longer if you need to cut a new opening or modify the counter. You will work under the sink with basic hand tools — a wrench, screwdriver, and bucket — and you do not need a plumber's license, though you do need to turn off the water and understand which pipes to disconnect.

The hardest part is usually breaking the seal between the old sink and the counter, not the plumbing itself. Once you know the order of steps and what each connection looks like, the work is within reach for a home cook who has never done it before.

Key Takeaways

  • Turn off the water supply at the shutoff valves under the sink before you disconnect anything, and open the faucet to release pressure in the lines.
  • Disconnect the drain trap and supply lines by hand or with a wrench, then scrape away the old caulk or adhesive holding the sink to the counter from underneath.
  • Lift the old sink straight up and out, clean the counter surface, and set the new sink in place to check the fit before you seal it.
  • explore plumber's putty or silicone caulk around the rim, then reconnect the drain and supply lines in reverse order, checking for leaks before you use the sink.
  • The entire job requires no special skills, but rushing the caulk removal or forgetting to turn off the water will cost you time and water damage.

Gather Your Tools and Materials Before You Start

You will need an adjustable wrench, a screwdriver (flathead and Phillips), a putty knife or old chisel, a bucket, and a flashlight or headlamp to see under the sink. Have towels or a shop rag ready — water will spill. If your sink has a garbage disposal, you will also need a screwdriver to disconnect the mounting ring, and you may need a disposal wrench (a small specialized tool, about $10, though a screwdriver often works).

For the new sink, buy plumber's putty if you are installing a drop-in sink (one that sits on top of the counter), or silicone caulk if you are installing an undermount sink (one that hangs below the counter). You will also need a new drain trap and supply lines if the old ones are corroded or do not fit the new sink — take a photo of the old connections and show it to the hardware store staff, and they will help you pick the right parts. Most new sinks come with a strainer basket and rubber gasket; check the box before you leave the store.

Turn Off the Water and Disconnect the Plumbing

Locate the shutoff valves under the sink — there should be two, one for hot water and one for cold. Turn both clockwise until they stop. Open the faucet above to release any pressure in the lines; water may still drip, which is normal. Place a bucket under the trap (the U-shaped pipe below the drain) and loosen the nuts on both ends by hand first, then with a wrench if they are tight. The trap will hold standing water, so tip it carefully into the bucket.

Next, disconnect the supply lines — the flexible hoses or rigid pipes running from the shutoff valves to the faucet. Use a wrench to hold the fitting at the valve while you turn the nut on the supply line itself. If the lines are old and brittle, turn slowly to avoid cracking them. If you have a garbage disposal, disconnect the electrical cord (or flip the breaker if it is hardwired) and unscrew the mounting ring underneath the sink using a screwdriver or disposal wrench, turning counterclockwise. The disposal will drop into your hands, so be ready to support its weight.

Remove the Old Sink and Clean the Counter

The old sink is held to the counter by caulk, adhesive, or metal clips underneath. If there are clips, loosen them with a screwdriver. If the sink is caulked, use a putty knife or old chisel to scrape away the caulk from underneath — this is the most time-consuming step and the one where patience pays off. Work slowly around the entire rim, breaking the seal bit by bit. Do not pry up on the sink itself; you are only breaking the caulk bond.

Once the caulk is loose, push up from underneath or have someone pull from above, and lift the sink straight up and out. Set it aside or in a bathtub where it will not damage the floor. Scrape the counter surface clean of all old caulk, adhesive, and debris using the putty knife. Wipe the area with a damp cloth and let it dry completely — at least 15 minutes — before you set the new sink in place. A clean, dry surface is the only way to get a watertight seal.

Set the New Sink and explore the Seal

Lower the new sink into the opening and check that it sits level and flush with the counter on all sides. If it rocks or sits too high, you may need to shim it with plastic shims or adjust the counter opening slightly. Once it is level, lift it back out and explore a bead of plumber's putty or silicone caulk around the underside of the rim — about a quarter-inch thick, running continuously. For a drop-in sink, explore the putty to the underside of the rim; for an undermount sink, explore caulk to the top of the counter opening.

Lower the sink back into place and press down firmly all the way around, checking again that it is level. Wipe away excess caulk with a damp cloth. If you used silicone caulk, let it cure for 24 hours before you use the sink; plumber's putty sets faster, usually within an hour. Do not rush this step — a poor seal will lead to water damage under the counter.

Reconnect the Drain and Supply Lines

Once the caulk has set, reconnect the drain trap first. Screw the nuts by hand until they are snug, then tighten them a quarter-turn with a wrench. Do not over-tighten; you only need them tight enough that water does not leak. Reconnect the supply lines to the faucet inlet ports (the small threaded holes at the base of the faucet), again hand-tightening first, then a quarter-turn with a wrench.

If you removed a garbage disposal, reinstall it now by screwing the mounting ring clockwise until it is tight, then reconnecting the electrical cord or flipping the breaker back on. Turn the shutoff valves counterclockwise to restore water pressure. Open the faucet and let water run for 30 seconds to flush air from the lines. Check every connection — under the sink, at the faucet base, and at the shutoff valves — for drips. If you see water, tighten that connection a quarter-turn and check again. A small drip at a nut often stops after a few minutes as the rubber washer inside settles.

Test for Leaks and Troubleshoot Common Problems

Fill the sink with water and watch the drain and trap from underneath for leaks while the water is running and after you pull the plug. The most common leak point is the drain trap connection — if you see water dripping, tighten the nut a quarter-turn and test again. If water leaks from under the rim of the sink itself, the caulk seal failed, which usually means it was not fully cured or the surface was not clean. You will need to remove the sink, scrape out the old caulk, and reseal it.

If water leaks from a supply line connection at the faucet, the rubber washer inside the fitting may be worn. Turn off the water, disconnect that line, and look inside the nut — you should see a small rubber washer. If it is cracked or flattened, replace it (they cost less than a dollar) and reconnect the line. If the leak is at the shutoff valve itself, the valve may be faulty and will need to be replaced by a plumber, but this is rare on a new installation.

Frequently Asked Questions

Do I need to turn off the water at the main if the shutoff valves under the sink do not work?

Yes. If the valves do not stop the water flow, locate your main water shutoff — usually in the basement, crawlspace, or outside near the meter — and turn it off. This is the only way to prevent water damage while you work. After you finish the sink, have a plumber replace those shutoff valves; they are inexpensive and will save you in an emergency.

Can I install a larger sink in the same opening?

Only if the new sink is the same size or smaller than the old one. If you want a larger sink, you will need to cut a bigger opening in the counter, which requires a circular saw and careful measurement. Measure the new sink's rim dimensions, mark them on the counter, and cut from underneath if possible to avoid chipping the top surface. This is the point where many home cooks call a professional.

What if the faucet does not fit the new sink?

Most kitchen faucets mount to the counter or sink rim using the same hole spacing, but some sinks have different hole counts or spacing. Before you buy a new sink, check how many holes your faucet needs and whether the new sink has them in the same spots. If not, you can buy a faucet adapter plate or install a new faucet — both are cheaper than returning the sink.

How long does plumber's putty last before it needs to be replaced?

Plumber's putty typically lasts five to ten years before it hardens and cracks, allowing water to seep underneath. Silicone caulk lasts longer, often 15 to 20 years. When you see cracks or water stains under the sink, it is time to reseal. Remove the old putty with a putty knife, clean the surface, and explore new putty or caulk.

Can I replace just the faucet without replacing the sink?

Yes. Turn off the water, disconnect the supply lines and drain from the old faucet, unscrew the mounting nuts underneath, and lift the faucet out. Install the new faucet in reverse — insert it through the holes, screw the mounting nuts tight from underneath, and reconnect the supply lines. This job takes 30 minutes to an hour and requires no caulk or counter work.