Install Your Kitchen Sink and Faucet
This is one of the most satisfying moments in your renovation—when you finally have running water in your new kitchen. Installing the sink and faucet correctly ensures years of leak-free operation and marks the beginning of your kitchen becoming functional again.
Quick Summary
Time needed
3-4 hours
Difficulty
Moderate (DIY-friendly)
Helper needed?
Yes, for undermount sinks
Before You Begin
Installing a sink and faucet is manageable for most DIYers, but there are a few tricks that make the difference between a smooth installation and a frustrating one.
Pro Tip: Install the faucet on the sink before you mount the sink in the countertop. Trying to attach a faucet from underneath in a cramped cabinet is miserable. Do yourself a favor and attach it from above while the sink is still accessible.
Tools You'll Need:
- •Basin wrench (essential)
- •Adjustable wrench
- •Channel locks or pipe wrench
- •Caulk gun and silicone
- •Plumber's putty
- •Teflon tape
- •Bucket and rags
- •Flashlight or headlamp
Step-by-Step Installation
1. Install the Faucet First
Before the sink goes in the counter, install the faucet through the sink holes. This is so much easier than working upside down in a cabinet.
- •Read the faucet instructions—each brand is slightly different
- •Feed the supply lines through the sink holes from above
- •Install the rubber gasket or use plumber's putty as directed
- •From below, thread on the mounting hardware and tighten with a basin wrench
- •Make sure the faucet is straight before fully tightening
Common Mistake: Forgetting to install the deck plate (the trim piece that covers extra holes). Install it before you tighten the faucet mounting nuts.
2. Mount the Sink in the Countertop
The mounting method depends on your sink type. Undermount and drop-in sinks use different techniques.
For Undermount Sinks:
- 1.Apply a generous bead of 100% silicone to the underside lip of the countertop cutout
- 2.Lift the sink (you'll need a helper) and position it carefully
- 3.Install the mounting clips or brackets per manufacturer instructions
- 4.Tighten clips evenly to create even pressure all around
- 5.Wipe away excess silicone that squeezes out
For Drop-In Sinks:
- 1.Run a continuous bead of silicone around the sink rim
- 2.Carefully lower the sink into the cutout opening
- 3.Press down evenly around the edges to seat it
- 4.Install clips underneath if provided (some don't have them)
- 5.Wipe away excess caulk with a damp cloth immediately
Pro Tip: For undermount sinks, have your helper support the sink from below while you tighten clips from above. Use 2x4s or a jack to take the weight off while you work.
3. Connect the Water Supply Lines
Now connect the faucet to the house water supply under the sink.
- •Identify hot (usually left) and cold (usually right) shutoff valves
- •Attach braided supply lines to the faucet tailpieces if not already connected
- •Connect the other end to the shutoff valves—hot to hot, cold to cold
- •Wrap threaded connections with 2-3 wraps of Teflon tape in a clockwise direction
- •Hand-tighten first, then use a wrench for a quarter to half turn more
Warning: Don't over-tighten supply line connections. The brass fittings can crack if you gorilla-grip them. Snug is enough—you can always tighten a bit more if it leaks.
4. Install the Drain Assembly
The drain assembly includes the basket strainer, tailpiece, and P-trap that connects to your waste line.
- •Install the basket strainer with a rope of plumber's putty under the rim
- •From below, install the rubber gasket, friction ring, and locknut
- •Tighten the locknut while holding the strainer so it doesn't spin
- •Attach the tailpiece to the strainer
- •Connect the P-trap between the tailpiece and the wall drain stub-out
- •Adjust the P-trap sections to fit—they slide and swivel for alignment
Tip: The P-trap creates a water seal that prevents sewer gas from entering your home. All connections should be hand-tight plus a quarter turn—no pipe dope or Teflon tape needed on the rubber compression washers.
5. Install Garbage Disposal (If Applicable)
If you're installing a garbage disposal, it replaces the standard drain basket in one of your sink bowls.
- •Install the disposal mounting assembly to the sink drain opening
- •Lift the disposal and twist it onto the mounting ring (have a helper hold it)
- •Lock it in place with the mounting tabs
- •Connect the discharge tube to the P-trap or to the other sink bowl
- •Wire the disposal to the electrical supply (turn off circuit first!)
- •If connecting a dishwasher, knock out the disposal inlet plug and attach the hose
Safety First: Turn off the circuit breaker before wiring the disposal. If you're not comfortable with electrical work, hire an electrician for this part—it only takes them 15 minutes.
6. Test Everything Thoroughly
Don't skip this step. Finding a leak now is easy. Finding it six months from now when your cabinet is full of mold is not.
- •Turn on the water supply valves slowly
- •Check for leaks at the supply line connections
- •Run both hot and cold water for several minutes
- •Fill both basins completely, then let them drain
- •Use a dry paper towel to check every connection under the sink
- •Run the disposal with water flowing to check for disposal leaks
- •Check the sink rim seal for any water seeping through
Success: If everything is dry after 10 minutes of testing, congratulations! You've successfully installed your sink and faucet. The first time you wash your hands in your new kitchen is a great moment.
Common Issues and Solutions
Supply lines dripping at shutoff valve
Solution: Tighten the connection slightly with a wrench. If it still leaks, shut off water, remove the connection, check that the rubber washer is seated properly, and reconnect. Sometimes the washer is crooked or damaged.
Water pooling around the sink rim
Solution: The seal isn't complete. For drop-in sinks, you may need to remove the sink, clean off the old caulk, and reinstall with a fresh bead. For undermount sinks, you may be able to add more silicone to gaps from below.
P-trap connections dripping
Solution: Make sure the rubber compression washers are in place and seated correctly. Hand-tighten the slip nuts, then use channel locks for just a quarter turn more. Over-tightening can actually cause leaks by deforming the washer.
Drain basket strainer leaking
Solution: Remove the strainer assembly and check that you used enough plumber's putty under the rim. You should see putty squeeze out when you tighten it. Also verify the rubber gasket and friction ring are installed in the correct order below.
Frequently Asked Questions
Should I install the faucet before or after mounting the sink?
Always install the faucet before mounting the sink. Working from above to attach the faucet, supply lines, and mounting hardware is dramatically easier than trying to do it from underneath in the cramped cabinet space. This is one of those "trust us on this" tips that will save you hours of frustration.
How do I know if my sink needs plumber's putty or silicone?
For undermount sinks attached to the underside of the countertop, use 100% silicone sealant. For drop-in sinks that rest on top of the counter, use silicone or plumber's putty around the rim. For drain basket strainers, plumber's putty is traditional and easier to remove later. Check your sink's installation instructions for specific requirements.
What's the biggest mistake people make when installing a kitchen sink?
Not testing for leaks thoroughly before closing everything up. Run water for at least 5-10 minutes, fill both sink basins completely and let them drain, and check every connection with a dry paper towel. A small drip now becomes a cabinet full of mold in six months. Also, over-tightening connections—hand-tight plus a quarter turn is usually enough.
Do I need a plumber to install a garbage disposal?
If you have basic DIY skills and an existing disposal outlet under the sink, you can install a disposal yourself. The mounting ring attaches to the sink drain, the disposal twists onto the mounting ring, and you connect the discharge pipe and plug it in. However, if you need to add an electrical outlet or are uncomfortable with the plumbing connections, hiring a plumber for an hour or two is money well spent.
How tight should I make the supply line connections?
Hand-tight plus about a quarter to half turn with a wrench is perfect. Over-tightening can crack fittings or damage washers, causing leaks. Use Teflon tape on threaded metal connections, but don't use it on compression fittings that have rubber washers—the washer does the sealing. After testing, you can always tighten a connection slightly if it drips.
Ready for the Next Step?
With your sink and faucet installed, it's time to position and connect all your major appliances.