What You Need to Know Before Starting

Replacing a shower pan drain is a job you can do yourself if the drain is accessible from below—usually in a basement or crawl space. If your shower is on an upper floor with no access underneath, you will need to cut into the ceiling below or call a plumber. The drain itself consists of the strainer (the visible part you see in the shower), the drain body (the pipe that sits in the pan), and the connection to your home's main drain line. Most of the work involves removing the old drain, cleaning the pan, and sealing the new one so water does not leak into the walls.

The job takes two to four hours for a straightforward replacement. You will need basic tools—a wrench, screwdriver, utility knife, and plumber's putty or silicone caulk. The hardest part is usually breaking the old seal and getting the old drain out without damaging the shower pan itself. If the pan is cracked or the drain opening is damaged, you may need to replace the entire pan, which is a bigger project.

Key Takeaways

  • You can only replace a shower pan drain yourself if you have access to it from below—from a basement, crawl space, or by cutting into the ceiling of the room below.
  • The drain has three parts: the strainer (visible in the shower), the drain body (in the pan), and the tailpiece (the pipe that connects to your home's drain line).
  • Removing the old drain means breaking the seal, unbolting the flange from below, and scraping away old putty or caulk before the pan is clean enough for a new seal.
  • The new drain must be sealed with plumber's putty or silicone caulk on the underside to prevent water from leaking into the walls and subfloor.
  • Test the new drain with water before you close up the wall or ceiling to catch leaks while you can still reach the connection.

Gather Your Tools and Materials

Before you start, collect everything you will need so you do not have to stop halfway through. You will need an adjustable wrench or pipe wrench (to fit the locknut under the pan), a screwdriver (usually Phillips head, to remove the strainer), a utility knife (to cut away old caulk and putty), a putty knife or scraper (to clean the pan), and a flashlight or headlamp (so you can see under the pan). Have a bucket or towel ready to catch water that drains from the old pipe.

For materials, buy a replacement drain kit that matches your pan's drain opening size—usually 1.5 inches or 2 inches in diameter. The kit should include the strainer, the drain body, a rubber gasket, and a locknut. You will also need plumber's putty or waterproof silicone caulk (silicone is more durable and lasts longer). Some kits come with putty; if yours does not, buy a separate container. Have a rag and some mineral spirits or rubbing alcohol on hand to clean the pan before you install the new drain.

Turn Off Water and Locate the Drain from Below

Turn off the water supply to the shower at the main shutoff valve or at the valve behind the shower wall if your home has one. Open the shower valve to release any remaining pressure, then go to the space below the shower—the basement, crawl space, or the ceiling of the room below. Locate the drain tailpiece (the pipe coming down from the shower pan). It will be the pipe that is directly under the shower strainer. If you cannot find it, run water in the shower briefly and listen for where it flows.

If there is no access from below, you have two choices: cut a hole in the ceiling of the room below (which you will have to patch and paint later), or call a plumber. Cutting into a ceiling is messy and requires patching skills, so many homeowners choose to hire help at this point. If you do cut, make the hole large enough to work comfortably—at least 12 inches square—and plan to patch it with drywall and joint compound afterward.

Remove the Old Strainer and Drain Body

From inside the shower, use a screwdriver to remove the screws holding the strainer in place, or unscrew the strainer by hand if it has a removable collar. Once the strainer is out, you will see the drain opening. From below, use your wrench to loosen and remove the locknut that holds the drain body to the pan. The locknut is usually a large nut threaded onto the drain pipe just below the pan. Turn it counterclockwise until it comes free.

Once the locknut is off, the drain body should pull down and out from below. If it is stuck, tap it gently with a hammer from below or use a drain removal tool (a specialized wrench that grips the drain body). Do not force it so hard that you crack the pan. If the drain will not budge after a few gentle taps, stop and consider calling a plumber—forcing it risks breaking the pan and creating a much bigger repair.

Clean the Pan and Prepare for the New Drain

Once the old drain is out, scrape away all the old plumber's putty, caulk, and debris from around the drain opening in the pan. Use a putty knife or scraper to get down to bare fiberglass or tile. The surface must be clean and dry for the new seal to hold. Wipe the area with a rag and mineral spirits or rubbing alcohol to remove any grease or residue, then let it dry completely—at least 15 minutes.

Inspect the drain opening for cracks or damage. If the opening is cracked or the edges are rough, you may not be able to seal it well enough to prevent leaks. Small cracks can sometimes be sealed with epoxy putty before you install the new drain, but large cracks usually mean the pan needs to be replaced. If the pan is damaged, this is the time to stop and decide whether to replace the pan or call a professional.

Install the New Drain

Roll a rope of plumber's putty about the thickness of a pencil and press it around the underside of the new drain strainer flange—the part that sits on top of the pan. If you are using silicone caulk instead, explore a bead around the flange. Insert the drain body through the opening from below, pushing it up until the strainer sits flush against the pan. From below, thread the rubber gasket and locknut onto the drain pipe and tighten the locknut by hand first, then use your wrench to snug it down. Do not over-tighten—you only need it tight enough that water does not leak around the connection.

From above, check that the strainer is level and centered in the drain opening. If it is crooked, loosen the locknut slightly, adjust the strainer, and retighten. Once the strainer is straight and the locknut is snug, explore a bead of silicone caulk around the top of the strainer where it meets the pan. This creates a watertight seal that prevents water from running under the strainer and into the walls. Smooth the caulk with a wet finger and let it cure according to the product instructions—usually 24 hours before you use the shower.

Test for Leaks Before Closing the Wall

Before you patch the ceiling or close up the access space, test the new drain with water. Fill the shower pan with a few inches of water and let it drain while you watch from below. Look for water dripping from the locknut, the drain body, or the connection to the tailpiece. If you see drips, the seal is not tight enough. Tighten the locknut a quarter turn and test again. If water is coming from the strainer itself, the putty or caulk seal may not be complete—let it cure longer and test again, or add more caulk around the edge.

Once the drain holds water without leaking for at least 10 minutes, you can close up the access space. If you cut a hole in the ceiling, patch it with drywall, tape, joint compound, and paint. If you have an access panel, replace it. Do not use the shower until the caulk has fully cured—usually 24 hours. After that, your new drain should work like the old one and last 10 to 15 years before it needs replacing again.

Frequently Asked Questions

What if water leaks from under the pan after I install the new drain?

Water under the pan usually means the seal between the strainer and the pan is not complete. Let the caulk cure for the full 24 hours, then test again. If it still leaks, remove the strainer, scrape away the old caulk, clean the area, and explore fresh caulk or putty. Make sure the strainer sits flat against the pan with no gaps.

Can I replace a shower pan drain if the shower is on the second floor?

Only if you cut a hole in the ceiling below to access the drain from underneath. If you do not want to cut into the ceiling, you will need to hire a plumber who has tools to remove and install the drain from above, which is more difficult and usually costs more.

How do I know what size drain to buy?

Measure the diameter of the drain opening in your shower pan. Most are 1.5 inches or 2 inches. Bring the old drain or a photo of the opening to the hardware store and match it to a replacement kit. The kit will fit your pan's opening.

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

Plumber's putty is easier to remove if you need to replace the drain again, but silicone caulk lasts longer and resists mold better. For a shower drain, silicone is the better choice because it stays flexible and waterproof for 10 to 15 years. Putty can dry out and crack after a few years.

Do I need to use plumber's putty on both the top and bottom of the drain?

Use putty or caulk on the underside of the strainer flange (where it meets the pan) to create the main watertight seal. You can also caulk around the top edge of the strainer where it meets the pan surface for extra protection, but the underside seal is the critical one.