Leaks only when the tub drains
No leak while the tub is filling or sitting full, then water shows up below once you pull the stopper.
Start here: Start with the bathtub drain flange, drain shoe gasket, and the waste-and-overflow connection.
Bathtub leak diagnosis
Bathtub Drain Leaking Through Ceiling
Direct answer: If water shows up through the ceiling below a tub, the bathtub drain is a common cause, but it is not the only one. First figure out whether the leak happens only while the tub is draining, only when the water is running, or only when the water level reaches the overflow.
Most likely: Most often, the leak is at the bathtub drain shoe gasket or the overflow gasket, especially when the ceiling leak appears during or right after a bath drains out.
Start with a simple water test and watch the timing. If it leaks only during draining, stay focused on the bathtub drain connection first. If it leaks while the faucet is running before the tub even drains, look at the spout, valve wall, or supply piping instead. Reality check: the drip you see in the ceiling is often several feet away from the actual leak. Common wrong move: cutting a big ceiling hole before doing a controlled tub test.
Don’t start with: Do not start by buying a new bathtub drain assembly just because the stain is under the tub. A loose drain flange, failed overflow gasket, cracked tub around the drain, or a supply-side leak can drip to the same spot.
Leaks only when drainingCheck the bathtub drain flange, drain shoe gasket, and waste connection first.
Leaks while filling tooShift early to the spout, overflow, valve wall, or supply piping instead of guessing at the drain.
Last reviewed: 2026-04-04
What the leak pattern is telling you
Leaks when the water level reaches the overflow
The ceiling stays dry during a shower or shallow fill, but leaks when the tub is filled higher for a bath.
Start here: Focus on the bathtub overflow plate and overflow gasket before the main drain.
Leaks while the faucet is running even before draining
Water appears below while filling the tub or while the shower is on, even with the drain closed.
Start here: This points away from the drain and toward the tub spout, valve wall, shower riser, or supply piping.
Leaks after someone stands in the tub
The leak is worse with body weight in the tub or when someone shifts around near the drain end.
Start here: Look for movement at a loose bathtub drain flange, a failed drain shoe gasket, or a crack around the tub drain opening.
Most likely causes
1. Loose or poorly sealed bathtub drain flange
This is the classic leak when water escapes around the drain opening and shows up below mainly during draining or when someone stands near the drain.
Quick check: Remove the stopper if needed and look for a flange that turns easily, missing putty or sealant squeeze-out, or staining around the drain opening.
2. Compressed, split, or misaligned bathtub drain shoe gasket
The gasket under the tub can leak only when water is moving through the drain or when the tub flexes under weight.
Quick check: If you have access from below or through a panel, look for the first wet point around the underside of the drain shoe, not the lowest drip.
3. Failed bathtub overflow gasket
If the leak starts only when the water level reaches the overflow opening, the overflow gasket is the better bet than the main drain.
Quick check: Fill the tub to just below the overflow and watch for leaks, then add another inch so water reaches the overflow opening and compare the result.
4. Tub spout, valve wall, or supply-side leak mistaken for a drain leak
Water can run along framing and drip through the same ceiling area, especially if the leak happens while filling or showering.
Quick check: Run the faucet with the drain closed and the tub nearly empty. If the ceiling leaks before draining starts, stop chasing the drain.
Step-by-step fix
Step 1: Contain the leak and pin down when it happens
The timing tells you more than the stain does. You want to know whether this is a drain leak, overflow leak, or supply-side leak before opening anything up.
- Stop using the tub until you can test it in a controlled way.
- If water is actively dripping through the ceiling, place a bucket under the drip and protect the floor.
- If the ceiling is bulging with trapped water, stop and consider a pro before it lets go unexpectedly.
- Dry the tub area and the ceiling area as much as you can so fresh water is easier to spot.
- Run three short tests: faucet running with drain closed, tub filled but not overflowing, and tub draining after the faucet is off.
- Write down exactly which test creates the leak and how quickly it shows up below.
Next move: You now know which side of the tub to chase first instead of guessing from the ceiling stain. If the leak pattern is still unclear, you need better access and a direct view of the plumbing before replacing anything.
What to conclude: A leak during draining points to the bathtub drain path. A leak during filling points to the spout, valve wall, riser, or supply piping. A leak only at high water level points to the overflow.
Stop if:
- Water is pouring through the ceiling instead of dripping.
- The ceiling drywall is sagging badly or looks ready to collapse.
- You cannot safely access the tub area without standing in water or on an unstable surface.
Step 2: Separate the drain from the overflow
These two leaks get mixed up all the time because both can drip into the same ceiling bay.
- Close the stopper and fill the tub to a few inches below the overflow opening.
- Wait several minutes and check below for any leak.
- If it stays dry, add water until it just reaches the overflow opening or trickles into it.
- Watch below again and note whether the leak starts only after water reaches the overflow.
- If the leak starts only at the higher level, remove the overflow plate screws and check for a loose plate or a shifted gasket if you have safe access.
Next move: If the leak appears only when water reaches the overflow, you have narrowed it to the bathtub overflow gasket or plate area. If it still leaks below the overflow level or only when draining, move back to the main bathtub drain connection.
What to conclude: Overflow-only leaks usually come from a hardened or misaligned bathtub overflow gasket, not the main drain flange.
Step 3: Check the bathtub drain opening from above
A loose drain flange or failed seal at the tub opening is common, visible, and less invasive to confirm than opening the ceiling first.
- Remove the stopper if it blocks your view of the drain flange.
- Clean soap film from around the drain opening with warm water and mild soap so you can see the metal-to-tub joint clearly.
- Press gently around the drain opening and watch for movement, gaps, or cracked tub material.
- Try turning the bathtub drain flange lightly by hand or with the proper drain tool if you have one. It should not spin loosely.
- If the flange is obviously loose and the tub surface around it is sound, retightening or resealing the bathtub drain flange is a reasonable next repair path.
Next move: A loose flange with no tub cracking strongly supports a bathtub drain flange reseal or replacement. If the flange feels solid, the leak is more likely under the tub at the drain shoe gasket or at the overflow branch.
Step 4: Inspect the first wet point from below or through an access opening
The first wet point is the truth. The lowest drip is just where gravity drops it.
- Use an existing access panel if you have one. If not, look for the least-destructive viewing point before opening a large section of ceiling.
- Have one person run the same controlled tub test while another watches with a flashlight.
- Start dry, then look for the first bead of water at the underside of the bathtub drain shoe, the overflow elbow, or the tub spout and valve piping area.
- If water forms right at the underside of the drain opening, the bathtub drain shoe gasket is the leading suspect.
- If water starts at the overflow elbow only when the tub is filled high, the bathtub overflow gasket is the likely fix.
- If water appears on supply piping, the tub spout drop, or inside the wall before any draining happens, stop this page and treat it as a supply-side bathtub leak instead.
Next move: You have the leak source narrowed to the exact bathtub component instead of replacing parts blindly. If framing is wet everywhere and you cannot identify the first wet point, open access may need to be widened or a plumber may need to pressure-test and inspect it directly.
Step 5: Make the repair that matches the test result, then retest hard
Once the leak source is clear, fix that exact point and prove it before closing anything up.
- If the bathtub drain flange was loose or leaking at the tub opening, remove and reseal or replace the bathtub drain flange and confirm the tub surface is not cracked.
- If the underside of the drain shoe was the first wet point, replace the bathtub drain shoe gasket and reassemble the drain connection squarely without over-tightening.
- If the overflow test was positive, replace the bathtub overflow gasket and tighten the overflow plate evenly so the gasket seats flat.
- After the repair, run the same three tests again: faucet running, tub filled below overflow, and full drain-down.
- Leave the access area or ceiling opening exposed until everything stays dry through a full bath-level test.
A good result: If all three tests stay dry, you can let the area dry fully and then close up the access or repair the ceiling.
If not: If the leak remains after the matched repair, the tub may have a crack, the waste-and-overflow assembly may be misaligned, or the leak may actually be coming from the wall side. At that point, bring in a plumber before replacing more bathtub parts.
What to conclude: A successful retest confirms you fixed the actual leak point, not just the part closest to the stain.
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FAQ
Can a bathtub drain leak only when the tub is draining?
Yes. That is one of the strongest clues that the main bathtub drain connection is the problem. A loose bathtub drain flange or a failed bathtub drain shoe gasket often stays quiet while the tub is full, then leaks once water starts moving through the drain.
Why is the ceiling leaking below the tub if the drain looks dry from above?
Because the leak may be under the tub, not at the visible top edge. Water can slip past the drain opening, the overflow gasket, or nearby piping and travel along framing before it finally drips through the ceiling.
Is the overflow more likely than the main drain?
Only if the leak starts when the water level reaches the overflow opening. If the tub can sit full below the overflow without leaking, then starts leaking once water touches the overflow, the bathtub overflow gasket moves to the top of the list.
Should I open the ceiling or the tub access side first?
Use any existing access panel first. If there is no access, do the controlled water tests before cutting. Once you know whether the leak is drain, overflow, or supply-side, you can open the smallest area that gives you a direct view of the first wet point.
Can I just tighten the bathtub drain and be done?
Sometimes, but only if the flange is actually loose and the tub is not cracked around the opening. If the leak is from the drain shoe gasket underneath or from the overflow, tightening the top flange will not solve it and can make diagnosis harder.
What if the leak happens while filling the tub, not while draining?
Then stop chasing the drain first. That pattern points more toward the tub spout, valve wall, shower riser, or supply piping. Water from those spots often runs to the same ceiling area and fools people into replacing drain parts they did not need.