What you need before you start

Replacing a bathtub faucet is a task most homeowners can do in an afternoon with basic tools. You will need an adjustable wrench, a screwdriver (both Phillips and flathead), a flashlight or headlamp, and possibly a basin wrench if your faucet sits in a tight space. Have towels ready — water will spill. Before you touch anything, turn off the water supply to the bathroom. Look under the sink or in the basement for the shutoff valve; if you cannot find it, turn off the main water supply to the house.

Know what type of faucet you have. Most bathtub faucets are either single-handle, double-handle, or cartridge-style. The replacement faucet you buy must match your plumbing setup — specifically, the number of holes in your tub deck and the distance between them (called the "spread"). Measure this distance before you shop. If you are unsure, take a photo of your current faucet and bring it to a hardware store; staff can help you find a compatible replacement.

Key Takeaways

  • Turn off the water supply before you begin, and test that the water is actually off by turning the handle.
  • Remove the handle and trim ring first, then use a wrench to unscrew the faucet body from underneath the tub deck.
  • The new faucet goes in the same holes; align it, hand-tighten the mounting nuts, then tighten with a wrench from below.
  • Reattach the handle and trim ring, turn the water back on, and check for leaks at all connection points.
  • If water leaks from under the deck after installation, the mounting nuts are too loose; tighten them slightly and test again.

Remove the old faucet handle and trim

Start by removing the handle. On single-handle faucets, look for a small screw or set screw hidden under a decorative cap. Pry the cap off gently with a flathead screwdriver, unscrew the handle screw, and lift the handle away. On double-handle faucets, do this for each handle separately.

Next, remove the trim ring (also called an escutcheon) — the decorative ring that sits against the wall or tub deck. It usually screws on or clips in place. If it screws on, turn it counterclockwise by hand or with a wrench. If it clips, pry it gently with a flathead screwdriver. Once the trim is off, you will see the faucet body and the mounting nuts underneath the deck.

Disconnect the faucet body from below

Crawl under the tub or into the access space below the deck with your flashlight. You will see the faucet body held in place by two or three mounting nuts. Use an adjustable wrench to turn these nuts counterclockwise. They may be tight, so apply steady pressure rather than forcing them. As you loosen each nut, support the faucet body from above with your other hand so it does not fall.

Once the nuts are loose enough, unscrew them by hand and set them aside. The old faucet body will now pull free from above. Before you remove it completely, check if there are supply lines (the flexible hoses that carry hot and cold water) attached to the faucet. If so, use an adjustable wrench to disconnect them at the faucet end. Water may drip — have a towel ready.

Install the new faucet body

Clean the holes in the tub deck where the old faucet sat. Remove any old caulk or debris with a scraper or old cloth. Position the new faucet so its body sits centered in the holes and the spout points toward the tub. The faucet should sit flat against the deck.

From underneath, hand-tighten the mounting nuts onto the faucet body. Once they are snug by hand, use your adjustable wrench to tighten them further — turn clockwise until they are firm but not over-tight. Over-tightening can crack the faucet or strip the threads. A good rule: tighten until you feel resistance, then give the wrench a quarter turn more. The faucet body should not move when you push on it from above.

Reconnect the water supply lines

Locate the hot and cold water supply lines. These are usually flexible hoses that come from the wall or floor. Connect them to the corresponding inlets on the new faucet body — hot to hot, cold to cold. Use an adjustable wrench to tighten the connection nuts by hand first, then with the wrench. Do not over-tighten; these connections are easy to crack. Hand-tight plus a quarter turn is usually enough.

If your new faucet came with new supply lines, use those instead of the old ones. Old lines can crack or leak, especially if they have been in place for years. Wrap the connection threads with plumber's tape (also called PTFE tape or Teflon tape) before screwing on the nuts — wrap it clockwise around the threads three times. This creates a watertight seal.

Reattach the handle and trim ring

Screw the trim ring back onto the faucet body by hand, then tighten it with a wrench if needed. It should sit flush against the tub deck or wall with no gaps. Reattach the handle by sliding it onto the stem, aligning any notches or tabs, and screwing in the handle screw. Replace the decorative cap over the screw.

Test the handle to make sure it moves smoothly and does not bind. If it does, remove it and check that the stem is seated correctly. The handle should turn from fully off to fully on without resistance.

Turn the water back on and test for leaks

Go to the shutoff valve and turn the water supply back on slowly. Listen and watch for any spraying or dripping. Turn on the faucet and let water run for 30 seconds to flush out any debris from the lines. Check the handle operation — it should turn smoothly and the water should stop completely when fully off.

Now inspect for leaks. Look under the tub deck with your flashlight. Check the connection points where the supply lines meet the faucet body, and check the mounting nuts. Water should not be dripping or pooling. If you see a small drip at a supply line connection, use your wrench to tighten that nut a quarter turn and test again. If water leaks from under the deck around the faucet body itself, the mounting nuts are too loose — tighten them slightly from below and test again.

Run the faucet for a few minutes and check once more. If everything is dry, you are done. If a leak persists after tightening, turn off the water, remove the faucet, and inspect the mounting surface for cracks or debris that might prevent a watertight seal.

Frequently Asked Questions

Do I need to use plumber's tape on every connection?

Use it on threaded connections where water flows through — the supply line connections to the faucet body and the trim ring if it screws on. Do not use it on the mounting nuts that hold the faucet body in place from below; those are compression fittings and do not need tape.

What if the old faucet is stuck and will not unscrew?

Spray the mounting nuts with penetrating oil (like WD-40) and wait 15 minutes. Try again with your wrench. If they still will not budge, apply heat with a hair dryer for a minute to expand the metal slightly, then try once more. Do not force it — you risk cracking the faucet or stripping the threads.

Can I install a new faucet if my tub has a different number of holes than the old one?

No. The faucet must match the number and spacing of holes in your tub deck. If your new faucet has a different spread, you will need to either drill new holes (which requires a drill and a steady hand) or choose a faucet that matches your existing holes. A hardware store can help you find the right fit.

Why is water leaking from under the deck even though I tightened everything?

The mounting surface may have debris or old caulk preventing a seal. Turn off the water, remove the faucet, clean the deck thoroughly, and reinstall. Alternatively, the faucet body itself may be cracked — if leaking continues after cleaning and reinstalling, the faucet is defective and should be exchanged.

Do I need to caulk around the trim ring?

Yes, once you confirm there are no leaks. Apply a bead of silicone caulk around the edge where the trim ring meets the tub deck or wall. This prevents water from seeping behind the trim and causing mold or rot. Let the caulk cure for 24 hours before using the tub.