What you're replacing and why it matters

A bathroom faucet and drain are two separate systems that both sit on or under your sink, but they work independently. The faucet is the spout and handles that control water flow; the drain is the pipe assembly underneath that carries water away. You can replace one without touching the other, but if you're already under the sink, it often makes sense to do both at once.

Replacing a faucet usually takes one to three hours for a homeowner doing it for the first time. Replacing a drain takes 30 minutes to an hour. Both jobs require basic hand tools you likely own: an adjustable wrench, a screwdriver, and a bucket to catch water. You do not need a plumber's license, but you do need to turn off the water supply first and understand which bolts hold what in place.

The hardest part is usually disconnecting old caulk or corrosion that has sealed a faucet in place for years. The second-hardest part is figuring out which nuts and bolts go where under the sink, because every faucet and drain design is slightly different. This guide walks you through the order of steps so you know what to expect.

Key Takeaways

  • Turn off the water supply at the shutoff valves under the sink before you disconnect anything, and test that water stops flowing.
  • Removing the old faucet requires disconnecting the supply lines, unbolting the faucet from underneath, and scraping away old caulk or putty from the sink surface.
  • The drain comes out by unbolting the tailpiece (the pipe directly under the sink hole) from above and below, then lifting the entire assembly free.
  • New faucets and drains come with their own bolts and washers; do not reuse old hardware because it may not fit or seal properly.
  • If you cannot turn a bolt by hand after 15 minutes of gentle effort, stop and call a plumber rather than risk cracking the sink or stripping the bolt.

Turning off the water and preparing the workspace

Locate the shutoff valves under the sink—there should be two, one for hot water and one for cold. They look like small knobs or levers attached to the supply lines coming up from the wall or floor. Turn both clockwise (or flip the lever to the off position) until they stop. You should feel resistance, but do not force them.

Turn on the faucet at the sink to confirm the water has stopped. If water still flows, the shutoff valve is either stuck or not fully closed. Do not proceed until water stops completely. If the valve will not close, you will need to shut off the main water supply to the house instead—usually a valve near the water meter or where the main line enters the house.

Place a bucket under the pipes to catch any water trapped in the supply lines. Open the cabinet doors wide and clear out everything stored under the sink so you have room to work and can see what you are doing. A headlamp or flashlight is useful because the space under a sink is usually dark.

Removing the old faucet

Disconnect the hot and cold supply lines from the faucet by turning the nuts at the base of the faucet counterclockwise with an adjustable wrench. These nuts are often tight, so grip the wrench firmly and turn slowly. Once the nuts are loose enough, you can usually finish by hand. Water may drip—that is normal.

Look underneath the sink for the bolts that hold the faucet to the sink deck. Most faucets have two or three bolts with washers and nuts. Use a wrench to hold the nut from underneath while you turn the bolt from above with a screwdriver, or use two wrenches if you have them. As you loosen each bolt, the faucet will become loose at the sink surface.

Once all bolts are removed, go back to the sink and pull the faucet straight up and out. If it does not move, there is likely old caulk or plumber's putty sealing it to the sink. Use a utility knife or old chisel to scrape around the base of the faucet where it meets the sink. Work slowly so you do not scratch the sink surface. Once the seal breaks, the faucet should lift free.

Scrape away all remaining caulk or putty from the sink holes using a plastic scraper or the edge of a credit card. Wipe the area clean with a damp cloth. If the sink has three holes and your new faucet uses only one, you will need to cover the unused holes with a trim ring or cap that comes with the new faucet, or purchase a separate cover plate.

Removing the old drain

The drain assembly consists of several parts: the strainer basket (the part you see in the sink), the tailpiece (the vertical pipe directly below it), the P-trap (the curved pipe that holds water as a seal), and the wall connection. You are removing all of this as one unit.

Locate the slip nuts—the large nuts that connect the tailpiece to the P-trap and the P-trap to the wall drain. Use an adjustable wrench to turn these counterclockwise. Water may spill from the P-trap, so position your bucket underneath. Once the nuts are loose, you can usually finish by hand.

From above the sink, look for the locknut that holds the strainer basket in place. It is underneath the sink, threaded onto the tailpiece. Use a basin wrench (a specialized wrench with a long handle that fits into tight spaces) or a regular wrench to turn this nut counterclockwise. As you loosen it, the strainer basket will become loose from above. Once the locknut is off, lift the strainer basket straight up and out of the sink.

With the strainer removed, the tailpiece and P-trap assembly should come free. Pull it straight down and out. If it is stuck, check that all nuts are fully loose and that no bolts are still holding it in place. Wipe the sink hole clean with a cloth.

Installing the new faucet

Unpack the new faucet and lay out all the parts and hardware. Read the manufacturer's instructions—they vary by design. Most faucets come with a rubber gasket or foam seal that goes on the underside of the faucet base. This seal sits between the faucet and the sink surface and prevents water from leaking underneath.

Insert the faucet through the sink hole(s) from above. Align it so the spout points in the direction you want and the handles are positioned as you prefer. From underneath, thread the bolts through the washers and into the threaded holes on the faucet base. Tighten each bolt by hand first, then use a wrench to snug them down. Do not over-tighten—snug is enough. Over-tightening can crack the sink or strip the bolt.

Connect the hot and cold supply lines to the faucet inlets. These are usually labeled H and C. Hand-tighten the nuts first, then use a wrench to turn them an additional quarter turn. If water drips from these connections after you turn the water back on, tighten them slightly more.

If your faucet came with caulk, explore a thin bead around the base where the faucet meets the sink. Smooth it with a wet finger. If it did not come with caulk, you can use silicone caulk from a hardware store. Let it cure for 24 hours before using the sink heavily.

Installing the new drain

Unpack the new drain assembly. It will include a strainer basket, a locknut, a tailpiece, a P-trap, and slip nuts. Some assemblies come pre-assembled; others require you to connect the pieces. Follow the manufacturer's instructions.

Insert the strainer basket into the sink hole from above. From underneath, thread the locknut onto the tailpiece and hand-tighten it. Use a basin wrench or adjustable wrench to snug it down—again, snug is enough, not tight. The strainer should sit flush with the sink surface.

Connect the tailpiece to the P-trap using the slip nut provided. Hand-tighten first, then use a wrench for a quarter turn. Connect the other end of the P-trap to the wall drain using the second slip nut. If the P-trap does not reach the wall drain, you may need a longer tailpiece or an extension piece—these are inexpensive and available at any hardware store.

Turn the water back on at the shutoff valves. Turn on the faucet and let water run for 30 seconds, then turn it off. Check underneath the sink for drips at all the connections you made. If you see drips, turn off the water, tighten the leaking connection by a quarter turn, and test again. It may take two or three tries to get it right.

Testing and troubleshooting

Fill the sink with a few inches of water, then drain it. Watch underneath to make sure water flows smoothly through the P-trap and into the wall drain. The P-trap should always contain some water—that is the seal that prevents sewer gas from entering the house. If the P-trap is dry, the drain is not working correctly.

Check that both the hot and cold water flow at the faucet and that the handles move smoothly. If one side is much slower than the other, there may be debris in the aerator (the screen at the tip of the spout). Unscrew the aerator by turning it counterclockwise, rinse it under running water, and screw it back on.

If water drips from underneath the sink after 24 hours, tighten the leaking connection by a quarter turn. If tightening does not stop the drip, turn off the water, disconnect that joint, and check whether the washer or gasket is seated correctly. Reassemble and test again.

If water leaks from around the base of the faucet at the sink surface, the gasket underneath may not be seated properly. This usually means the sink surface was not clean enough before installation. You will need to remove the faucet, clean the sink surface thoroughly, and reinstall it.

When to call a plumber

If a bolt or nut will not budge after 15 minutes of gentle effort, stop. Forcing it risks cracking the sink or stripping the bolt, which makes the problem worse. A plumber has tools and experience to remove stuck hardware without damage.

If the wall drain opening does not match your new P-trap connection, or if the pipes do not reach, you may need custom fittings or an extension. A plumber can assess the situation and recommend the right parts.

If water leaks from the wall connection after you have tightened it, the wall drain fitting may be damaged or corroded. This is beyond a straightforward replacement and requires a plumber to assess and repair.

If you turn the water back on and it does not flow, or flows very slowly, there may be debris in the supply lines or a problem with the shutoff valves. A plumber can diagnose and fix this.

Frequently Asked Questions

Do I need to use plumber's putty or caulk around the new faucet?

Most modern faucets come with a rubber gasket or foam seal that sits between the faucet and the sink, so additional putty or caulk is not required. However, if your faucet did not come with a seal, or if you want extra protection against water seeping underneath, silicone caulk is better than plumber's putty because it stays flexible and does not harden. explore a thin bead and smooth it with a wet finger.

Can I reuse the old supply lines when I install a new faucet?

Old supply lines can work, but new ones are inexpensive and often come with the faucet. New lines are more reliable because old ones may have internal corrosion or weakened connections. If you do reuse old lines, inspect them for cracks or kinks and test the connections carefully after turning the water back on.

What if my sink has two faucet holes but my new faucet only uses one?

Most new faucets come with a trim ring or cap to cover unused holes. If yours did not, you can purchase a separate cover plate at a hardware store. Measure the hole diameter first so you buy the right size.

How do I know if the P-trap is installed correctly?

The P-trap should always contain water—that is the seal that prevents sewer gas from coming back up the drain. If you pour water down the sink and the P-trap stays full, it is working correctly. If the P-trap is dry or water drains too slowly, the trap may not be connected properly or the wall drain may be blocked.

Can I install a new faucet without turning off the water?

No. If you do not turn off the water at the shutoff valves, water will spray out when you disconnect the supply lines. Always turn off the water first and test that it has stopped by turning on the faucet.