How to Change a Bathtub Drain

Changing a bathtub drain means removing the old flange, cleaning the seat, then threading in a new drain with the right seal for your tub.

A tired drain can leave stains, slow flow, and that faint sewer smell after a long soak. The fix is usually a flange swap, not a full rip-out.

You’ll get steps, the tools that actually bite, and a few “stuck drain” saves. If you move slow and keep the finish protected, this is a solid DIY job.

What You’re Replacing And What Parts Matter

The metal ring you see is the drain flange. It threads into the drain shoe under the tub. The flange seals to the tub surface; the shoe ties into the waste pipe.

Most of the time you replace the flange and the stopper trim. If the shoe is cracked or the gasket under the tub is torn, you’ll need access from below to finish the repair.

Drain Style	What You’ll Notice	Best Removal Grip
Crossbar flange	Two bars across the opening	Drain wrench or dumbbell tool
Toe-touch stopper	Tap down to close, tap to open	Unscrew stopper first, then drain wrench
Lift-and-turn stopper	Knob lifts, then twists to lock	Remove set screw, then drain wrench
Trip-lever pop-up	Overflow lever controls a plug	Remove linkage, then drain wrench
No-crossbar flange	Open ring, smooth inside	Internal pipe wrench or extractor
Plastic flange	Lightweight, often white	Wide pliers with gentle pressure
Corroded flange	Pitting, thin edges, flaking	Extractor plus penetrating oil
Silicone-beaded rim	Clear bead at the tub surface	Cut bead, then drain wrench

Tools And Supplies To Gather Before You Start

Get everything in reach, then start. Pausing mid-job can leave you with an open pipe and a tub you can’t use.

Drain wrench (tub drain remover)
Adjustable wrench or large pliers
Utility knife and plastic scraper
Rag, gloves, small bucket
Plumber’s putty or 100% silicone
New drain flange (match finish and size)

Nice-to-have backups: penetrating oil, internal pipe wrench, and a drain extractor for broken crossbars.

Buying The Right Replacement Drain Before You Open Anything

Most tubs use a 1-1/2 inch drain, yet finishes and thread styles vary. The simplest move is to buy a replacement flange that matches the old one: same outside diameter, same crossbar layout, same stopper style, and a finish that matches your faucet trim.

If your old flange is badly corroded, take a clear photo from above and measure the visible opening across the threads. Many home centers sell “universal” kits, but the threads still need to match the drain shoe or you’ll fight a bind on the first turn.

Before you start, keep this in mind: how to change a bathtub drain is mostly about thread fit and a clean seal, not muscle. If the new flange won’t spin in by hand for the first few turns, stop and swap to the correct part.

This is the repeatable flow that fits most tubs. Read it once, then follow it in order.

Step 1 Protect The Tub And Pull The Stopper

Lay a towel in the tub so tools don’t chip enamel. Remove the stopper parts. Toe-touch and lift-and-turn stoppers often unscrew once you open them. Some use a tiny set screw.

If you have a trip lever, remove the overflow plate and slide the linkage out as one piece. Set it aside on a towel.

Step 2 Cut The Old Seal

Run a knife around the outer edge of the flange where it meets the tub. Cut until you can slip a plastic scraper under the rim. Clear away loose sealant so your wrench sits flat.

Step 3 Unthread The Old Flange

Seat the drain wrench into the crossbars and turn counterclockwise. Keep the tool vertical. A tilted bite snaps crossbars fast.

If it won’t move, add penetrating oil, wait ten minutes, then try again with steady pressure. Light heat on the flange can help too, but keep it moving and avoid heating acrylic hard.

Step 4 Clean The Seat And Check The Threads

Lift out the flange and scrape off every trace of putty or silicone on the tub surface. Wipe with alcohol or mineral spirits until it feels clean and dry.

Look down into the opening and inspect the drain shoe threads. If they’re cracked or stripped, the flange can’t hold. That’s the point where access from below matters.

Step 5 Pick Putty Or Silicone Based On The Tub

Many porcelain and metal tubs work well with plumber’s putty under the flange lip. Many acrylic and fiberglass tubs call for silicone instead, since some putties can react with plastics. Oatey’s page on using plumber’s putty spells out where it fits and where it doesn’t.

Some manufacturers warn against putty on acrylic. A Delta installation document notes “Do not use plumber’s putty to seal the drain flange” for acrylic surfaces; see the Delta drain flange instruction for that caution.

Step 6 Install The New Flange

Roll putty into a rope and wrap it under the flange lip, or lay a thin silicone bead under the lip. Set the flange into the opening and turn it clockwise by hand for the first few turns. If it doesn’t catch smoothly, back off and restart.

Once it’s hand-tight, use the drain wrench to snug it down. Stop when you see a small, even squeeze-out ring. Over-tightening can distort gaskets below and can crack plastic parts.

Wipe away squeeze-out. Putty lifts with a rag. Silicone needs a scraper, then a wipe after it skins.

Step 7 Reassemble And Water Test

Reinstall the stopper and overflow plate. Fill the tub with a few inches of water, then drain it while you watch the flange edge. Run hot water for a minute too, since heat can reveal a weak seal.

If you can reach the plumbing from below, check for drips at the shoe while the tub drains fast.

Pull the rag from the opening, then rinse the tub. If hair or grit drops into the drain, grab it with a hook tool before it reaches the trap below.

Changing A Bathtub Drain With A Stuck Flange

Some drains act like they’re welded in. Corrosion and old sealant can lock the flange to the shoe.

Use Steady Pressure And Keep The Tool Seated

Hold the drain wrench down with one hand and turn with the other. If you’re using a dumbbell remover, slide a screwdriver through the holes for extra reach and turn slowly.

If the tool cams out, stop and re-seat it. Slips gouge finishes and chew crossbars.

Cut, Soften, Then Switch Tools

Cut the seal again, add penetrating oil, wait, then turn. If crossbars break, move to an internal extractor that bites the inside of the flange. Avoid prying up on the flange; that bends thin metal and scars the tub.

What Changes When You Have Access From Below

With access, you can hold the drain shoe steady while you turn the flange from above. You can also replace the shoe gasket if it looks flattened, torn, or stuck to the tub.

If you see water marks on the ceiling under the tub, plan to watch the joint below during the test. A dry rim on top doesn’t always mean the joint under the tub is sealed.

Symptom	Likely Cause	Fix
Drips under the tub	Shoe gasket pinched	Loosen, re-seat gasket, retighten evenly
Water beads at the rim	Old seal left behind	Remove flange, clean fully, reseal
Flange won’t tighten	Threads stripped in shoe	Replace drain shoe and gasket
Stopper won’t seal	Wrong stopper height	Adjust linkage or replace stopper seal
Slow drain after swap	Debris in trap	Flush, then snake gently if needed
Crossbars snapped	Corrosion or angled tool	Use internal extractor, turn slowly
Hazy ring on tub finish	Puttied on plastic surface	Clean residue, use silicone next time
Metal squeak while tightening	Dirty threads binding	Back off, clean threads, retighten

Small Details That Keep Leaks Away

Clean surfaces and even pressure beat brute force. Start the threads by hand, keep the flange level, and stop once you get an even squeeze-out ring.

If you used silicone, give it cure time before a long bath. Many 100% silicone products want a full day. Putty seals right away, but it can still shift if you crank the flange too hard.

A quick habit that helps: after the first test, wait fifteen minutes, then run a dry paper towel around the rim. It catches slow seepage that skin contact can miss.

When The Leak Isn’t The Flange

If the overflow gasket is brittle, water can run behind the wall once the tub level reaches that opening. If the trap is loose, the leak may show only during a fast drain.

A sewer smell that returns after the swap can also point to a dry trap or a venting issue, not a bad rim seal.

Quick Checklist Before You Put Tools Away

Sealant ring is even and cleaned up
Stopper opens and closes smoothly
Tub holds water for ten minutes with no damp rim
No drips below after a full drain cycle

Last Check And Future Swap Notes

If you ever revisit this job, the rhythm stays the same: remove the stopper, unthread the flange, clean the seat, reseal, then snug it down. Learning how to change a bathtub drain once makes the next swap feel routine.

Keep the old flange until the new one passes a full test. It’s a handy reference for thread size if you need a different drain trim later.