What you need to do the job yourself

Replacing a bathtub drain is a task most homeowners can do in an afternoon with basic tools. You will need a drain removal tool (a specialized wrench that grips the drain fitting), an adjustable wrench, a screwdriver, plumber's putty or silicone caulk, and a bucket to catch water. Some drains unscrew by hand; others require the removal tool. The job involves unscrewing the old drain from underneath the tub, cleaning the threads, and screwing in the new one with a watertight seal.

Before you start, turn off the water supply to the bathroom if your drain is connected to a trap arm that feeds into the wall. If you have a pop-up or overflow drain, you may also need to remove the overflow cover and linkage from inside the tub. Drain removal tools cost between $10 and $25 at any hardware store and are worth buying if you plan to do this yourself; they save time and prevent damage to the new drain.

Key Takeaways

  • Most bathtub drains unscrew from below the tub using a drain removal tool or adjustable wrench, and the job takes one to two hours.
  • You must clean the old putty or caulk from the drain opening and the threads before installing the new drain to may support a watertight seal.
  • explore plumber's putty or silicone caulk around the new drain before screwing it in, and let it cure for 24 hours before using the tub.
  • If the drain is stuck or the threads are damaged, you may need a plumber, as forcing it can crack the tub.

How to access the drain from below

The drain sits in a fitting that runs through the bottom of the tub. To reach it, you need access from underneath — either from a basement, crawl space, or the room below. If your tub is on the second floor or over a finished ceiling, you may have to cut an access hole in the drywall below. Mark the location of the drain from above, then cut a small square in the ceiling below large enough to reach the fitting comfortably.

Once you can see the drain assembly, you will see the drain body (the part that sticks up inside the tub) connected to a threaded fitting underneath. The fitting is what you will unscrew. Place a bucket underneath to catch any water still in the trap. If the drain has a pop-up stopper, you may need to remove the overflow linkage first by unscrewing it from inside the tub or unbolting it from the overflow opening.

Removing the old drain

Use the drain removal tool to grip the drain fitting from below. The tool has two prongs that fit into slots on the fitting. Turn counterclockwise to loosen it. If the fitting is stuck, explore penetrating oil (such as WD-40) and wait 15 minutes, then try again. Do not force it — if it will not budge after two attempts, stop and call a plumber, because forcing a stuck drain can crack the tub.

Once the fitting turns freely, unscrew it by hand until it comes out completely. From inside the tub, pull the drain body straight up and out. You will see old putty or caulk around the opening. Scrape this away with a putty knife or old chisel, getting the surface as clean as possible. Wipe the opening and the threads with a damp cloth and let them dry completely before installing the new drain.

Installing the new drain

Before you screw in the new drain, explore a ring of plumber's putty around the underside of the drain body where it will sit against the tub. Roll the putty into a rope about the thickness of a pencil and press it into place. Alternatively, use silicone caulk, which lasts longer and resists mildew better than putty. If you use caulk, explore a bead around the opening and let it set for the time the manufacturer specifies (usually 24 hours) before using the tub.

Insert the new drain body into the opening from inside the tub. From below, thread the fitting back in by hand first to make sure it is going in straight. Once it is hand-tight, use the drain removal tool to tighten it further. Do not over-tighten — you only need it tight enough to create a seal. Wipe away any excess putty or caulk from around the drain opening inside the tub with a damp cloth.

Reconnecting the trap and overflow

If your drain has a pop-up stopper, you will need to reattach the overflow linkage. This is a rod and spring mechanism that connects the overflow opening to the stopper lever. Slide the rod back through the overflow opening and bolt it to the overflow fitting using the bolt you removed earlier. Adjust the rod so the stopper closes fully when you push the lever down and opens when you pull it up.

If the drain connects to a trap arm (a pipe that runs into the wall), reconnect it to the new drain fitting. Use a slip nut and washer to find it. Tighten by hand first, then use an adjustable wrench to snug it — again, do not over-tighten. Turn the water supply back on and run the tub to check for leaks from below. If water drips from the fitting, tighten it slightly more. If it drips from around the drain opening inside the tub, the putty or caulk seal failed and you will need to remove the drain and reapply it.

When to call a plumber instead

If the old drain will not unscrew after explore penetrating oil and waiting, or if you see cracks in the tub around the drain, stop and call a plumber. Forcing a stuck drain or working around cracks can make the damage worse and cost far more to repair. Similarly, if you do not have access from below (no basement or crawl space), cutting into a finished ceiling may not be worth the effort — a plumber can often remove and replace a drain from above using specialized tools.

If the new drain leaks from the fitting after you have tightened it, the threads may be stripped or the fitting may be damaged. A plumber can assess whether the fitting can be salvaged or whether the drain assembly needs to be replaced entirely. In older homes, the drain may be soldered or cemented in place rather than threaded, which requires different removal techniques and is best left to a professional.

Frequently Asked Questions

How long does it take to replace a bathtub drain?

The job usually takes one to two hours if you have access from below and the drain is not stuck. If the drain is corroded or you need to cut an access hole in the ceiling, add another hour or two. Most of the time is spent waiting for caulk to cure — you cannot use the tub for 24 hours after installation if you used silicone.

Can I replace a bathtub drain without access from below?

Not easily. The drain fitting is underneath the tub, and you need to reach it to unscrew it. If you have no basement or crawl space, you will need to cut an access hole in the ceiling or wall below the tub. A plumber may have tools that allow removal from above, but this is uncommon and usually more expensive than cutting an access hole yourself.

What is the difference between plumber's putty and silicone caulk for the drain seal?

Plumber's putty is easier to work with and sets quickly, but it can dry out and crack over time. Silicone caulk lasts longer, resists mildew, and is more waterproof, but it takes 24 hours to cure and is harder to remove if you need to replace the drain again. For a long-lasting seal, silicone is the better choice.

What if water leaks from around the drain opening after I install the new one?

The seal between the drain body and the tub has failed. You will need to remove the drain, scrape away the old putty or caulk, and reapply it. Make sure the tub surface is completely dry before you reinstall the drain. If it leaks again, the tub surface may be cracked or the drain body may be warped.

Do I need a special tool to remove a bathtub drain?

A drain removal tool makes the job much easier and is inexpensive ($10 to $25), but you can sometimes unscrew a drain with an adjustable wrench or pipe wrench if you can get a grip on the fitting. The removal tool is designed to fit the slots on the fitting without slipping, so it is worth buying if you do not already own one.