How to Replace an Old Kitchen Sink With a New One

Swapping out a tired, stained, or just plain annoying kitchen sink for a shiny new model is one of those
upgrades that looks intimidating but is surprisingly doable for a handy homeowner. If you can turn off
a shutoff valve, use a wrench without hurting yourself, and tolerate a little time spent lying on your
back in a cabinet, you’re already most of the way there.

This guide walks you through how to replace an old kitchen sink with a new one, step by step, in the
spirit of This Old House: practical, detailed, and just a little bit nerdy about doing it the right way.
We’ll help you plan the project, disconnect and remove the old sink, prep and install the new one, and
reconnect all the plumbing without turning your kitchen into an indoor water feature.

Step 1: Plan Your Kitchen Sink Replacement Like a Pro

Before you touch a wrench, you’ll want a game plan. Replacing a kitchen sink is easiest when the new sink
fits the existing countertop opening and your plumbing layout doesn’t change dramatically. A little extra
planning up front can save hours of frustration later.

Match the Size and Style of the Existing Sink

Start by measuring your existing sink and the cutout in the countertop. Measure the overall length and
width of the sink, as well as the size of the basin opening. Most drop-in kitchen sinks follow standard
sizes (like 33 inches or 36 inches wide), but there are plenty of exceptions.

Sink width and front-to-back depth: Measure from left to right and from front edge to back edge of the rim.
Cutout size: If you can, measure the opening from underneath the counter where you can see the actual cutout.
Number of holes: Count faucet and accessory holes (for a sprayer, soap dispenser, or filtered water tap).

Choosing a new sink with the same overall dimensions and similar rim style (drop-in/top-mount vs.
undermount) usually means you won’t need to cut or modify your countertop. If you’re upgrading from a
double-bowl to a large single-bowl sink, double-check that your plumbing trap and dishwasher or disposal
connections can still line up with the new drain location.

Gather Your Tools and Materials

You don’t need a full plumbing truck to tackle this project, but you will need a basic set of hand tools
and a few supplies.

Common tools

Adjustable wrench and/or basin wrench
Channel-lock pliers
Screwdrivers (flathead and Phillips)
Putty knife or scraper
Utility knife
Bucket and old towels or rags
Jigsaw (only if the countertop opening needs adjustment)
Flashlight or headlamp (your future self under the sink will thank you)

Materials

New kitchen sink (preferably same size as existing)
New faucet and accessories (optional but highly recommended)
Plumber’s putty or sink manufacturer–approved sealant
Silicone caulk for sealing the sink to the countertop
New supply lines (braided stainless flex lines are easiest)
New P-trap or trap adapter, if existing parts are old or don’t line up well
New strainers and/or garbage disposal mounting kit

If your shutoff valves are ancient, consider picking up replacement valves. It’s a good opportunity to
upgrade if they don’t fully shut off or are heavily corroded.

Step 2: Shut Off Water and Power

This is the “don’t flood the kitchen” part. Under the sink, you should see a hot and cold shutoff valve
feeding the faucet. Turn both handles clockwise until they stop. Then open the faucet to relieve pressure
and make sure the water is really off.

If you have a garbage disposal, turn off power at the wall switch and flip the breaker in your
electrical panel. It’s overkill until someone accidentally flips the switch while you’re working in the
cabinetthen it’s just smart.

For extra safety, unplug the garbage disposal and any under-sink appliances like instant hot-water
dispensers.

Step 3: Disconnect the Plumbing and Accessories

Now it’s time to release the old sink from its tangle of pipes and hoses. Keep a bucket and towels handy
there’s almost always a bit of residual water hiding in the lines.

Disconnect supply lines and faucet

Use an adjustable wrench or basin wrench to loosen the nuts connecting the supply lines to the shutoff valves.
Loosen the mounting nuts that hold the faucet to the sink from underneath. These are often located on threaded rods at the base of the faucet.
Lift the faucet out from above and set it aside. If you’re installing a new faucet, you can discard the old one.

Disconnect the drain, disposal, and dishwasher line

Place a bucket under the P-trap (the U-shaped section of pipe) and loosen the slip nuts with pliers or by hand.
Let any water in the trap drain into the bucket and remove the trap assembly.
If you have a garbage disposal, follow the manufacturer’s directions to unmount it from the sink and disconnect its discharge pipe.
Disconnect the dishwasher drain hose from either the disposal or the sink tailpiece and set it aside.

Once the supply lines, drain, and disposal are disconnected, your old sink is basically just hanging on by
clips and caulk.

Step 4: Free the Old Sink From the Countertop

Most drop-in sinks are secured with metal clips underneath and a bead of caulk around the rim. Removing
them is more about patience than brute force.

Crawl under the sink and locate the mounting clips around the perimeter. Use a screwdriver or nut driver
to loosen them and pivot them away from the countertop.
From above, run a utility knife around the edge of the sink to cut through the old caulk bead.
Gently work a putty knife under the rim of the sink, prying carefully. Move around the perimeter to
gradually break the seal.
Once the sink is loose, lift it straight up and out of the countertop cutout. This is easier with two
people, especially for heavy cast-iron or composite sinks.

With the sink removed, scrape off any leftover caulk or putty from the countertop surface. A clean, smooth
rim is crucial for a good seal with the new sink.

Step 5: Prep the New Kitchen Sink

Here’s where you start to feel like a real plumbing pro. Doing as much work as possible while the sink is
upside-down on a pair of sawhorses (or a padded counter) makes life under the cabinet much easier later.

Dry-fit the sink

Before you attach anything, drop the new sink into the opening to confirm the fit. Check that:

The rim fully covers the cutout.
The sink sits flat and doesn’t rock.
The bowls are centered the way you want them.

If the opening is slightly too small, you may need to enlarge it using a jigsaw, cutting carefully along a
marked line. If the opening is significantly too large or the countertop is stone, it’s wise to call in a
pro rather than improvising.

Install the faucet and sink accessories

With the sink on a stable work surface, install the faucet, side sprayer, soap dispenser, filtered water
tap, or any other accessories according to their instructions. It’s far easier to tighten mounting nuts
while you can actually see what you’re doing.

Next, assemble and install the basket strainers (and garbage disposal flange, if you have one). Typically,
you’ll:

Roll a rope of plumber’s putty and press it around the underside of the strainer flange.
Drop the strainer body into the drain hole from above.
From below, add the rubber gasket, friction ring, and locknut, then tighten until putty squeezes out evenly.
Wipe away excess putty around the drain opening.

Some modern sinks and strainers call for silicone instead of putty, so always follow the manufacturer’s
directions for the best seal.

Attach the mounting clips

Flip the sink carefully and attach the supplied mounting clips around the perimeter, pointing inward.
Spacing them evenly helps distribute pressure when you tighten them after the sink is in place.

Step 6: Set and Seal the New Sink

Now comes the oddly satisfying partdropping the new sink into place and seeing the transformation.

Run a continuous bead of high-quality kitchen- and bath-grade silicone caulk around the edge of the countertop opening or along the underside of the sink rim, depending on the manufacturer’s instructions.
Carefully lower the sink into the opening, making sure the faucet and any hoses slide through without snagging. Press the sink down gently so the caulk beds evenly.
From below, rotate each clip outward until it catches the underside of the countertop. Tighten the screws or nuts a little at a time, moving around the sink in a crisscross pattern so you don’t warp the rim.

As you tighten, the sink should snug down against the countertop and a small bead of caulk will squeeze out
around the rim. Wipe this away with a damp finger or cloth for a neat finish.

Step 7: Reconnect the Plumbing

With the sink anchored, it’s time to reconnect everything and make the new setup watertight.

Reconnect supply lines

Attach new flexible supply lines to the faucet (if they aren’t factory-installed).
Thread the other end of each line onto the hot and cold shutoff valves by hand, then snug them with a wrench. Don’t overtighten.

Flexible braided lines are your best friend herethey can handle small alignment changes without kinks. If
your old lines look worn or are stiff, replacing them is inexpensive insurance against leaks.

Reconnect drains, trap, and disposal

Attach the sink’s tailpieces and slip nuts to the strainers (these often come with the sink or strainer kit).
Dry-fit the P-trap assembly between the tailpiece and the wall drain. You may need a new tailpiece extension or additional fittings to reach comfortably without stressing joints.
If you have a garbage disposal, mount it to the new flange following the manufacturer’s instructions, then connect its discharge to the drain line.
Reattach the dishwasher drain hose to the disposal or to a branch tailpiece, making sure it loops up high under the counter to prevent backflow.

Hand-tighten all slip nuts first, then give them a cautious extra turn with pliers. They should be snug but
not crushed.

Step 8: Turn Everything Back On and Check for Leaks

Moment of truth time.

Remove tools and rags from the cabinet and place a dry paper towel under each connection.
Slowly turn the shutoff valves back on, watching for drips around the supply line nuts.
Plug in the garbage disposal and flip the breaker and switch back on (if applicable).
Run both hot and cold water, fill each basin, then let the water drain while you watch all the drain connections and the trap.

If you spot a small drip, gently tighten that connection a bit more and retest. Persistent leaks may mean a
misaligned washer or a cross-threaded nut that needs to be disassembled and reassembled.

Step 9: When to Call a Professional

While replacing a kitchen sink is within reach of many DIYers, there are a few situations where it’s smart
to hire a licensed plumber or countertop pro:

You have stone or solid-surface counters that need cutting or polishing.
You’re switching from a drop-in to an undermount sink (especially under stone).
You need to move the drain location more than a few inches.
Your shutoff valves or supply lines are severely corroded or frozen in place.
You’re uncomfortable working with electrical connections for the garbage disposal.

Even if you hand off part of the job, knowing the sequence and the terminology makes it easier to work with
a pro and understand what you’re paying for.

Real-World Lessons: What You Learn Replacing a Kitchen Sink

Replacing an old kitchen sink isn’t just about shiny stainless steel and deeper basins. The project teaches
you a lot about how your kitchen really worksand gives you plenty of stories to share.

Measure twice, shop once

Homeowners often discover, the hard way, that “close enough” measurements don’t cut it. A sink that’s even
half an inch too big may not fit between side walls or might bump into the backsplash. A sink that’s too
small can leave gaps along the rim that look sloppy and allow moisture to sneak into the countertop
substrate. Taking careful measurements (and bringing them to the store) is the difference between a smooth
afternoon install and an emergency countertop modification.

Budget time for surprises under the cabinet

Old shutoff valves that don’t actually shut off, corroded traps that crumble at a touch, mystery fittings
added by the previous ownerthese are all common discoveries. Many DIYers report that the “quick sink
swap” turned into an extra run to the hardware store for new valves, a fresh P-trap, and sometimes a new
supply line configuration. Building an extra hour or two into your schedule keeps those surprises from
feeling like setbacks.

Pre-assembling everything really does make it easier

The pros almost always install the faucet, strainers, and disposal flange while the sink is out of the
cabinet, and there’s a reason: gravity is nicer when you’re not lying on your back. Many homeowners who’ve
done this project once say that the second time, they assembled absolutely everything they could before
dropping the sink in, and the job went far faster with far fewer “where did that tiny nut go?” moments.

Flexible connections are lifesavers

Flexible braided supply lines and adjustable plastic traps forgive small alignment errors and changes in
sink depth. Rigid, old metal traps and solid copper lines, on the other hand, can turn a sink replacement
into a geometry puzzle. Swapping to modern flexible components doesn’t just make installation easier; it
also makes future maintenance simpler when you eventually replace a faucet, disposal, or dishwasher.

Don’t rush the leak test

One of the most shared “learned the hard way” stories is turning the water back on, glancing quickly at the
pipes, and calling it goodonly to discover a slow drip under the sink hours later. Let the water run, fill
the basins, and drain them fully while you watch each connection. Paper towels or tissue under fittings
make even tiny leaks obvious. Spending ten quiet minutes testing beats tearing out soggy garbage bags and
damaged cabinet bottoms later.

A new sink changes how your kitchen feels

Once the job is done, the payoff is bigger than you might expect. A deeper bowl means baking sheets and
stockpots finally fit. A pull-down faucet makes rinsing produce and dishes easier. A quieter, better
insulated sink cuts down on that “metal drum” sound when water hits the basin. Many homeowners say it’s one
of the most satisfying medium-sized DIY upgrades they’ve madelarge enough to notice every day, small
enough to tackle in a weekend.

In the end, replacing your old kitchen sink with a new one isn’t just a plumbing project; it’s a quality of
life upgrade for the space you use more than almost any other room in the house. With a bit of planning,
the right tools, and a calm approach to the occasional drip, you can pull it off and enjoy your “new” This
Old House–style kitchen centerpiece for years to come.