A Step-by-Step Guide for Installing a Bathroom Sink

Kathryn Pomroy
Written by Kathryn Pomroy
Updated May 9, 2022
woman turning on black faucet
Photo: Studio Luniste


Perfect for handy homeowners.

Time to complete

5 hours

4 to 5 hours



Installing a sink can save you money and can be done in an afternoon

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What you'll need:


  • Pipe (crescent) wrench, slip joint, or channel lock pliers
  • Basin wrench
  • Utility and putty knives
  • Bucket
  • Rags or a towel


  • New sink unit
  • Silicone caulking
  • Set of plumbing sockets
  • Plumber’s putty

Installing a bathroom sink is no small feat, but, if you’re handy, you can do it yourself in an afternoon—especially if you have a pair of helping hands. Or, you could hire a local pro to get the job done faster (and with less hassle on your part).

Pro Tip: Because you might also want (or need) to replace your sink fixtures and countertop, you also need to budget for those costs.

  1. Shut Off the Water Supply

    You’ll likely find two knobs below the sink. Turn both to off, then test your both hot and cold water to make sure nothing comes out. If you don’t find these knobs under the sink, you may have to turn off the main water supply.

  2. Remove Your Old Sink

    Using your channel lock pliers or a pipe wrench, disconnect the supply and drain lines from the faucet. Look for the large metal or plastic nut that connects the sink to the drain and disconnect it as well, then detach the P-trap section of the pipe. (You may not have to totally remove the P-trap, but you will need to loosen it). 

    Use a bucket to collect any water that drains out. Then, simply remove your sink. 

    You might need to slide a putty knife under and around the sink’s perimeter to loosen the caulk. If your old sink is glued down, you might need to use a chisel and hammer to free it from your countertop. 

    Pro Tip: If you’re reusing the drain (like the faucet) from your old sink, make sure to pay attention to how it’s fitted before removing it. That way you’ll know exactly what steps are needed to reattach it.

  3. Install the Faucet

    Installing the faucet is easier to do before you actually fit your new sink into place. Simply follow the instructions that came with your unit. 

    If you plan to keep using your old faucet, you likely don’t have instruction materials on hand. So, as you remove it, make notes on how it was installed originally so you can replicate the setup.

  4. Install Your New Sink

    Man installing bathroom sink
    Photo: Angelov / Adobe Stock

    Some sinks come with a gasket that seals the unit in place. If you don’t have a gasket, apply non-hardening plumber’s putty, caulking, or silicone to create a seal to prevent water from dripping through the gap. 

    If you’re installing an undermount sink, find another set of hands—unlike a drop-in sink, this type will need to be held in place or it will fall. For an undermount sink, apply the caulking, silicone, or plumber’s putty to the top rim before pushing it up into place. When your sink is in position, add any bolts or clips as necessary. 

    Wait until the caulking sets (about 24 hours) before proceeding to the next step. This ensures the sink doesn’t move while you reconnect the pipes and hoses.

  5. Reconnect the P-trap and Water Lines

    If you bought a new drain, it should come with instructions for proper installation. You can now reattach the P-trap and water lines by screwing the nuts back into place with your pliers or wrench.

  6. Caulk the Drain and Sink

    While you can caulk before you reconnect the water lines, sometimes it's easier after everything is reconnected to make sure everything lines up. 

    Add caulking all the way around the drain, remove any excess that oozes out, and wait about 24 hours before you use the sink to make sure the seal sets. You’ll also want to add a bead of caulk around the outside of the sink so no water leaks between the sink and the countertop.

  7. Test Your Handiwork

    When everything is reconnected, caulked, and dried, now’s the time to test your sink. Turn the water supply back on and run both the hot and cold water to be sure nothing leaks (it won’t hurt to have a bucket on hand, just in case).

Need professional help with your project?
Get quotes from top-rated pros.