How to Install a Bathroom Sink

January 13, 2023

Can you install a bathroom sink yourself? The answer is yes, though not everyone wants to take on that type of DIY responsibility. After all, when you’re dealing with water lines in your house—and possible flooding or other types of water damage—mistakes aren’t an option. 

If you’re ready to learn how to install a bathroom sink, however, you’re in the right place. In this article, we’ll cover everything you need to know, whether you’re trying to figure out how to install a pedestal sink, how to change a bathroom sink faucet, or how to attach a sink to a vanity. 

What Do I Need To Do Before Installing a Bathroom Sink?

Before you install your sink, you’ll need to measure your current sink and the surrounding area. You don’t want to go out and buy a sink or vanity without knowing if it will fit properly in your space—this would be a recipe for frustration and DIY blues. Make sure to measure your:

  1. Sink basin’s length, height, and width
  2. Sink’s length, height, and width
  3. Sink basin’s depth
  4. Faucet center / knob placements 
  5. Vanity length, width, and height (if applicable)

Measuring is key before buying a sink or vanity, and it will also help you figure out whether DIY is truly the route you want to take. Just make sure your space will fit whichever sink style you choose, whether it’s a single sink, double sink, or pedestal sink. 



What Tools & Materials Do I Need To Install A Sink?

Before you set out to install your sink, you’ll need the following tools and supplies:

Tools

  • Bucket
  • Utility knife
  • Putty knife
  • Rags
  • Channel lock pliers
  • Pipe wrench

Supplies

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

You’ll also want to make sure you have an extra set of hands if you’re choosing to DIY a sink installation. You’ll likely need help lifting and placing the sink and/or vanity. This is especially true for undermount sinks, which are attached underneath a hole in the counter or vanity top vs. hanging through a hole from above. 

How Much Does A Sink Repair Cost?

According to HomeGuide, a bathroom sink installation can cost anywhere between $380 – $1,200, depending on where you live, the type of materials you need to purchase, and the scope of your project. The cost includes:

Materials: $50 – $550

Labor fees: $230 – $650

You can definitely save on labor costs by making sink installation a DIY project, but you’ll need to understand basic plumbing, the space you’re working with, and any limitations it might present before you start your project. If you’re not the handy type, hiring help might be a safer option and save you time in the long run.

How much time, you ask? Well, it can take 4 to 5 hours for a professional to swap out a sink or replace a vanity and sink. If you don’t know what you’re doing, you can expect it to take much longer. Hiring an experienced Tasker will definitely relieve you of that headache!



How To Install A Bathroom Sink

When you’re ready to install your new bathroom sink, you’ll want to take a step-by-step approach. There are two main types of sinks to think about: pedestal sinks and vanity sinks. We’ll tackle them one at a time.

How To Install A Vanity Sink

Vanity sinks are very common in bathrooms and can provide much-needed surface space around the sink. To install a vanity sink, do the following:

  1. Shut off the water supply. Most sinks have two knobs underneath them connected to pipes—one for cold and one for hot. To shut off the water, turn these knobs clockwise until they’re tight. Test the hot and cold water in your sink to make sure no water comes out.
  1. Disconnect and drain the water lines. Using channel lock pliers or a pipe wrench, disconnect the water lines from the valves. Make sure you do this above a bucket to catch any water that needs to drain out.
  1. Disconnect the P-trap. Under your sink, there will be a curved section of piping—the P-trap. Place your bucket under this, and loosen the nut that connects to the sink’s drain pipe. You may be able to leave the P-trap connected to the wall, but your sink or vanity installation may require it to be removed altogether, until the new sink install is complete.
  1. Remove the old sink and vanity. You may need to slide a putty knife or other type of sharp blade around any edges that are sealed with caulking before removing your sink. For the vanity, unscrew any screws that are connecting it to the wall, and pull it away. Use an extra set of hands if necessary!
  1. Repair any damaged areas of the wall. This is a great time to patch up any wall damage in the sink area, or repaint the wall if the vanity was previously blocking paintable areas. 
  1. Install the new vanity. First, measure your vanity, and mark the wall where it should go. Then set your new vanity in place, aligning it to the marks on the wall. You can also remove the vanity’s doors to make installation easier, then reattach them once the main portion of the vanity is in place. Next, make sure the vanity is level—use shims if necessary. Once it’s perfectly level, drill pilot holes into the wall, and then attach it with screws. If you don’t have studs to drill into, you’ll need to use properly sized wall anchors.
  1. Install the vanity top (if applicable). If your vanity doesn’t come with a top, you can place the new one on the newly installed vanity, using caulking to glue it into place. Also use caulking to seal any areas where the vanity top touches the wall. If your vanity top has a sink attached to it, move on to step 9. 
  1. Install the sink. If you have a drop-in sink, place it in the hole of the vanity top, and seal all edges—including the drain—with caulking. (Note that it can sometimes be worth it to reinstall everything before sealing edges with caulking, just to make sure each element lines up!) For undermount sinks, you’ll need an extra set of hands. Once you have help, apply caulking, silicone, or plumber’s putty to the rim before pushing it up into place around the edge of the vanity’s sink hole. Add any bolts or fastening clips as necessary.
  1. Install the faucet, and reconnect the P-trap and water lines. Follow the manufacturer’s instructions to install your new water faucet. Make sure the hot and cold water lines are connected properly, and reinstall the P-trap the same way you detached it.
  1. Test. Seal. Use. Once everything is aligned, connected, and sealed, test out your sink. Use a bucket if necessary under any areas that might leak. Seal up any areas that do, and then you should be good to go!

How To Install A Pedestal Sink

Installing a pedestal sink is a fairly involved process, so before you try doing it, make sure DIY is the best route to take. Most pedestal sinks are actually attached to the wall using a mounting brace that must be built into the studs—their main base/stem is a secondary support. (Check your sink manufacturer’s instructions to see if this brace is necessary.) To install a pedestal sink, do the following:

  1. Shut off the water, remove the P-trap, and remove the old sink. Follow the steps listed above to do this. Once your old sink is gone, you can also repair and repaint the wall if necessary. 
  1. Install the mounting brace under the wall. Using a stud finder, determine where the wall studs are, and mark the height of the new sink on the wall and where it will fall between the studs. Then:
    1. Cut a 2×6’’ board the length of the recommended brace. This step is necessary if your sink requires a mounting brace. (You can also use a 2×8’’ board). 
    2. Cut a hole in the wall, and install the brace between the studs. Use an oscillating tool to cut through the drywall. Once the drywall is removed, cut shallow notches into the studs so that the 2×6’’ board can be placed flat inside them, creating a mounting brace inside the studs. (See this video for help!) If your wall has tile, you may need to remove the tile and replace them later.
    3. Patch up your wall, and repaint it. Use a new piece of drywall to patch up the hole. After spackling the edges, sand it to make sure it’s smooth and ready for paint. 
  1. If applicable, mark and drill holes for the sink’s hanger bolts. You may need to assemble your sink on its secondary support/pedestal to get an idea of how it will line up with the new brace and the holes you’re drilling. Once the spacing is confirmed, attach your hanger bolts to the new brace, leaving them extending from the wall about 1 inch.
  1. Alternatively, you can install your sink’s mounting bracket (if it has one). Anchor the bracket by screwing it into the 2×6’’ board you placed inside the wall.
  1. Install the sink drain. Most sinks don’t come with drains or faucets—you’ll likely have to purchase these separately. After wiping out any dust from your sink basin and drain hole, follow the manufacturer’s instructions to assemble the drain. Make sure you use the proper amount of plumber’s putty when installing the flange through the sink’s top, and make sure the gasket and washer are properly placed on the underside. Finally, screw the lock nut onto the drain, and tighten it by hand (but not too tight). 
  1. Attach the P-trap, and install the sink over it. After assembling the sink basin and pedestal away from the wall, test fit it with the P-trap to make sure all piping fits inside the pedestal through its open backside. Then:
    1. Remove the test build, and temporarily attach the P-trap to the wall’s waste pipe after measuring 1) from the floor to the top of the P-trap’s vertical portion and 2) from the floor up to the drain’s tailpiece. 
    2. Use this measurement to mark how high the P-trap should fit onto the drain’s tailpiece. 
    3. Next, remove the P-trap from the wall. Cover its threads with plumber’s tape to ensure a leak-free fit once it connects to the drain. 
    4. Put the P-trap’s slip nut and washer over the drain’s tailpiece, and then slide the P-trap up to the mark you made on the tailpiece. 
    5. Thread the slip-nut onto the P-trap, and tighten by hand. Then use a wrench to tighten it by a ¼ turn. 
    6. You’ll connect the P-trap back to the wall’s waste pipe at the end!
  1. Install the faucet. Without yet attaching the sink to the wall, follow the manufacturer’s guidelines to install the faucet. Place a ¾ inch thick rope of plumber’s putty around the underside of the flanges of the faucet’s valves and spout. Insert the faucet pieces into their proper holes in the sink basin. When you press the flanges down, wipe away any excess putty that pushes out. Thread the provided gasket and nut onto each piece’s underside, and tighten the nuts by hand before finishing with a wrench.
  1. Mount the sink. When all the pieces are assembled, move the sink basin and pedestal back to their final spot against the wall. Next, mount the sink basin to the mounting bracket. Or, if you installed hanger bolts earlier, align the sink basin so that the bolts extend through the mounting holes on the basin’s back side. After checking to make sure the sink is level, use cap nuts and washers to fasten it to the wall.
  1. Connect the plumbing. Consult the manufacturer’s directions for the specific faucet you bought, and make sure the P-trap is once again reconnected to the waste pipe running into the wall. Test it with water to make sure there are no leaks.
  1. Bolt the pedestal to the floor. Your pedestal sink should come with bolts to secure it to the floor. Don’t over-tighten them, as this can crack the pedestal. Check the manufacturer’s directions for specific guidelines.

Check out this article from Home Depot for more detail on installing a pedestal sink.



How To Change A Bathroom Sink Faucet

Before you replace your bathroom faucet, you’ll need to determine which type it is: 

  1. Single hole. These are single-handle faucets that operate through one hole.  
  2. Center set. This will require three holes—one for the actual faucet and two for the handles. There should be at least 4 inches between each piece and a cover or escutcheon plate that connects the pieces on top of the sink.
  3. Split set (a.k.a. widespread). These are designed to have 6+ inches between the handles and faucet.

Once you’ve determined which type of faucet you have (and read the directions), follow these general steps:

  1. Turn off the water supply. Turn off the “hot” and “cold” water lines that feed the faucet.
  2. Remove the old faucet. Use a wrench to unscrew the nuts under the sink that are keeping the faucet in place. After disconnecting the lift rod, pull the old faucet pieces up until they clear the sink. The pieces may be fixed to the sink, so use two hands to pull them off if necessary.
  3. Clean the sink’s surface. Use rubbing alcohol or all-purpose cleaner with a clean rag to make sure any adhesive or old putty is cleaned off the sink’s surface.
  4. Replace the drain pipe if needed. If your faucet kit includes a new drain, you can remove the P-trap and replace the drain. 
  5. Attach the new faucet. Place the rubber or plastic gaskets on top of the sink holes, and place the new faucet pieces in the appropriate place (again, consult the manufacturer’s directions).
  6. Seal the edges. Use bathroom caulking to seal the edges of the new pieces. 
  7. Put washers over the mounting nuts under the sink. Connect them by hand first, and then use a wrench or pliers to tighten them. 
  8. Attach the lift rod. This connects to the drain’s tailpiece to control the drain. 
  9. Connect the water supply lines. Make sure the “hot” and “cold” lines match to the proper taps.
  10. Test the faucet. Make sure to check all areas you worked on for leaks, and seal them if necessary!

Check out this article from Home Depot for more detail on replacing a bathroom faucet.

How To Attach A Sink To A Vanity

While we covered how to install a sink with a vanity above, you might simply be wondering how to attach a sink to a vanity. This is necessary whenever you buy a vanity base without an attached top, or if you’re only wanting to replace the top. To connect a sink to a vanity, do the following steps:

  1. Ensure the vanity is level and flush to the wall. There should be no space between the wall and the vanity.
  2. Add silicone caulking to the top rim of the vanity. This will adhere the vanity top to the vanity.
  3. Set the top piece into position. Make sure all elements align with the plumbing below, and press down to ensure the adhesive takes hold.
  4. Make sure the vanity top is flush to the wall and level. You may need to use shims if your vanity doesn’t come with adjustable legs.
  5. Secure the vanity to the wall, and add a backsplash. Once everything is in place, secure the vanity to the wall. You may also want to add a backsplash if your vanity top doesn’t have one built in. Seal all edges to protect against water damage.

As you can see, replacing or installing a bathroom sink is a bit more involved than your basic home improvement task—it’s definitely important to know what you’re doing if you’re planning to DIY. If your peace of mind is the most important factor, you can always hire a Tasker to make sure the job is done right.

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