Is Your Bathtub Leaking? How to Find and Fix the Source

The grout around the rim of my bathtub has had cracks in it for at least a year. I didn’t consider the problem urgent until I learned how much damage leaky water can do

To fix a leaking bathtub, first pinpoint the source of the leak. Common leak sources include eroded washers, cracks in grout, and rusted valves and pipes. Fixing a leaking bathtub often involves replacing damaged parts and adding new silicone sealant.

In this post, we’ll explore how to repare your bathtub leak in detail. Even if you’re a beginner at DIY, you can follow directions to know when a leak is easily fixable by you or when it’s best to call a plumber. I’ll also introduce you to some cool technology that can help you identify leaks the moment they start. 

And if you’re in urgent need of plumbing equipment, check out Plumbing Deals. You’ll find huge discounts on pumps, pipes, valvues, bathroom fixtures and other supplies you’ll need to fix a leaking bathtub.

How Much Danger Is a Leaking Bathtub?

All types of bathtub leaks are not created equal. This is because some can do quite a bit more damage than others, with the most dangerous types of leaks posing health hazards and costing you many thousands of dollars.

All leaks wastewater, and depending upon the extent and duration, they will drive up your water bill. While a leak in the plate on your shower control might drip water into the bathtub, a leak in an underlying pipe might go undetected for years until it rots out the wood on your floor and causes a bathroom mold problem.

Needless to say, the sooner you can catch a leak the better. And even more impressive would be to prevent leaks from happening in the first place.

Anatomy of a Bathtub

In order to identify the source of a bathtub leak and learn how to repare it, you’ll need to know what type of bathtub you have and what the various parts are called. 

What Type of Bathtub Do You Have?

First, you have the bathtub itself. There are 8 major tub types:

1. Alcove Tubs
2. Drop-In Tubs
3. Walk-In Tubs
4. Corner Tubs
5. Classic Clawfoot
6. Japanese Soaking Tubs
7. Contemporary Freestanding Tubs
8. Whirlpool and Air Tubs

If you have an alcove, drop-in, walk-in or corner tub, the rim around your bathtub connects to a wall or platform. It is sealed with silicone grout. The tile around your tub is filled in with caulking. 

What Material Is Your Bathtub?

Knowing the material of your tub can help you rule in and out various sources of leaks. Common bathtub materials include:

1. Fiberglass
2. Acrylic
3. Porcelain-Enameled Steel
4. Stone Resin
5. Stone
6. Porcelain-Enameled Cast Iron
7. Copper 
8. Wood

While it’s quite rare for a stone or copper tub to crack, an aging fiberglass or acrylic tub can sometimes spring leaks. Knowing what material your tub is made from and its age can help you rule in or out this possibility.

What Type of Bathtub Faucet Do You Have?

There are several types of bathtub faucets. No matter what type you have, your bathtub faucet has a spout, which is the hardware out of which the water pours into the tub. Faucets are either floor-mounted, wall-mounted or deck-mounted.  

Your bathtub also has either a 1-hole faucet handle that can be turned left or right for hot and cold water. The inside of a 1-hole faucet with a swivel handle can contain a cartridge, ceramic disk or a ball bearing. You cannot know which type of 1-hole faucet you have without taking it apart.

A 3-hole faucet, also called a compression faucet, has separate knobs for hot and cold water, plus the spout. This type of faucet allows the user to get more precise temperature control, but is more prone to leaks than a 1-hole faucet.

What Other Bathtub Hardware Is There?

Your tub also has an overflow drain. When the tub water fills higher than the overflow drain, the excess water will be sucked out of the tub and sent down the drainpipe through this part. There is also a drain on the bottom of the tub.

The bathtub faucets, overflow drain and drain are sealed to the wall or tub bottom with silicone sealant, which is supposed to prevent water from seeping behind the hardware.

Do You Have a Bathtub Access Panel?

Your house may have an access panel to the bathtub’s plumbing. This looks like a little cabinet that’s built into the floor or a wall near the tub. It allows you or a plumber to easily access water pipes. 

If you have an access panel, consider yourself in great luck because you won’t need to pull apart drywall in order to examine the water pipes for leaks. Instead, you can simply open the panel door.

5 Common Sources of Bathtub Leaks

Knowing the source of your bathtub leak is three-quarters of the battle. Let’s take a look at how you can track down the source of your bathtub leak, beginning with the 5 usual suspects:

1. Leaky Bathtub Faucet

A leak in the faucet is often readily apparent. You may see the water dripping out the spout, even when the knobs are turned to the off position. If this is the case, you’ll want to note if the leak is coming from the cold or hot water line, or maybe from both.

If you have a 1-hole faucet, feel the temperature of the drip to determine if the water is coming from the hot or cold water line. (If the water is warm, it could be coming from a combination of both lines.)

Do this test: Turn the hot water on for 10 seconds. Turn it off. Check for leaks using a flashlight to be sure you can really see what’s going on. Feel around the faucet and feel for any leaks that may be coming from where the faucet attaches to the wall. Repeat for cold water.

2. Leaking Caulk or Grout

If you have cracked caulking around the perimeter of your bathtub, chances are water is pouring in there whenever someone splashes in the tub or takes a shower. Consider it a slow-motion emergency. You won’t notice a problem for quite a long time—it could even be years! But eventually, your walls are likely to rot and you could easily have an unhealthy mold colony in your home.

So water can get into the cracks through caulking around the perimeter of your tub. It can also penetrate through cracks in the grout, if you have tile or a window behind your tub.

But water can also leak out of caulking that has eroded. This caulking might have been put in to seal the hardware in your bathtub to a wall, deck or even the floor. Water leaking out of sealants may be good news because it can be easy to fix; you may simply need to recaulk.

3. Leaky Bathtub Drain

If you notice the water in the tub sinks a few inches during the course of your bath, you probably have a broken drain plug or a leak in the overflow drain. 

A leaky drain can also present as a drip onto the ceiling of the floor below. So if you’ve got a water spot there, suspect a drain that may have loosened over time or the gasket inside the overflow has worn out.

Do this test: To check if you have a corroded gasket in the overflow, spray water from the showerhead directly onto the overflow drain. Does this reproduce the leak onto the floor below? If yes, bingo!

4. Cracked Tub Surface

Although much less likely than a leaking faucet or drain, it’s possible to get cracks in the bathtub material itself. This is much more likely to happen with acrylic or fiberglass bathtubs than steel-enameled or stone resin tubs. 

Do this test: Place a dry bed sheet flush against the side of the tub and on the floor. (You can drape it over the ledge on the top and weigh it down with a few heavy objects.) Now fill the tub. Is the sheet wet? Where is it wet? You should be able to tell if the problem is where the bathtub fits into the floor or platform, in which case you may have a problem with the seal. 

However, if the sheet is wet where it lay against the exterior side of the tub, then there could be cracks in the material. If this is the case, before you remove the sheet, mark where it is wet by putting a piece of tape on the spot on the tub.

5. Rusted Water Pipes and Valves

If you have a slow leak in underlying water pipes, you may not discover it until you have a mold problem or rotting drywall or a water spot on the ceiling of the floor below. In all of these cases, expensive damage has already been done. It’s best to repare the leaks as soon as possible.

But how will you know if the water pipes or valves are leaking? If you are fortunate enough to have an access panel, you can open it up. 

Use a flashlight to search for evidence of water. You may see actual drips or you may see dried watermarks. If you find either, look hard for the source. A drip on one pipe may be coming from another loose-fitting valve or pinhole in a pipe somewhere else.

If you don’t have an access panel, you have a few choices: 

1. Proceed with caution first, by thoroughly checking all other possible sources of leaks such as the bathtub faucet, drain, bathtub, caulk and grout. Then if you come up dry there proceed with more drastic measures.
2. Use technology to help you track the leak. 
3. Go to more drastic measures such as tearing out drywall yourself to locate the leak or calling in a professional.

Technology That Tracks the Source of a Bathtub Leak

In addition to using a flashlight to help you see well, technology can be a great asset in your hunt for the source of a leak. It can even prevent you from needing to cut into your ceilings or walls.

Moisture Meter

A good moisture meter can tell you if there is water in the floor, drywall or studs. It can pinpoint the exact source of a leak and the extent of the moisture present. The MMD4E Digital Moisture Meter and Water Leak Detector that we recommend is backlit making it easier to read the screen. You can judge if the leak is old or current by measuring the moisture over a period of days to see if it’s increasing.

Water Monitor

You can install the Flume Water Monitor on your water lines and it will instantly alert you to leaks, not only in your bathroom but anywhere inside or outside of your house. It comes with an app that will show you the source of a leak, as well as the overall water usage in your home. 

Keep in mind that while the moisture meter and water monitor are great for hunting down existing leaks, you can also use these devices to prevent problems from arising in the first place. 

A Step-By-Step Guide to Fixing a Leaky Bathtub

Once you’ve identified the source of the leak, you are in a very good position to fix it. Some leaks are trickier than others, and some people have more DIY know-how than others. 

You’ll need to judge where your leak and your skills fit on the spectrum. Then you can tackle the problem yourself—or call a plumber. 

If you’re going to DIY this, there are two things you need to do before you begin:

Turn Off the Water Supply

Before you attempt to repare a leaky faucet, you’ll want to turn off your water supply. (If you live in a condo or apartment, talk to the maintenance person. That person will notify others and then turn off the water for you.)

There are two places where you can go to shut off the water to your home: 

• At the outside water meter. You’ll open the lid and see the meter reading. There will be a key that you’ll need to turn from vertical to a perpendicular position.  

• At the inside water heater. You can also find a key to shut off the water valve where your water heater is located in your home. This is often in a garage or basement. Again, turn the key from vertical to perpendicular.

Now you’ll want to drain any remaining water from the pipes. To do this, turn on any water source in your home like the faucets, or flush the toilet. 

When nothing else comes out of the faucet or the toilet doesn’t refill, you are ready to repair your leaking bathtub.

Place a Cloth Over the Tub Drain

By covering the tub on the bottom of the drain, you’ll prevent the headache of accidentally dropping small screws and other parts down the drain. Of course, if you’re needing to reseal the drain itself, you’ll need to skip this step.

Next, go to the part of this guide that addresses the source of your leak:

Anatomy of a Bathtub Faucet

As already discussed, there are a variety of faucet types. Each requires its own steps to fix and there’s still a bit of detective work you’ll need to do. Often the problem is a worn-out washer, O-ring or gasket. These are tiny parts that can cause big problems.

 

Just like you needed to learn the parts of a bathtub, if you’ve discovered the source of the leaking water is in the faucet, you’ll need to drill down here, too. Try to get your mind around these parts that make up the inside of a bathtub faucet:

Cap

This is usually a round piece of plastic or metal that fits over the screw that is connecting the faucet handle to the interior faucet hardware. Its purpose is cosmetic. 

Cartridge

A cylindrical case that fits into the valve seat. The cartridge is plastic, ceramic or brass and replaces a traditional valve. It provides a smoother user experience for the person turning the faucet handles.

Clip

A tiny piece of metal used to hold cartridge or valve securely in place inside valve seat or sleeve

Sleeve

A metal ring that holds the cartridge for a swivel faucet in place.

Spring

A metal coil that fits on top of a washer and holds it firmly in place.

Valve

A metal piece that fits into a valve seat. When you turn a faucet handle, the valve adjusts to allow more or less water. Updated faucets contain cartridges instead of traditional valves.

Valve Seat

A piece of metal that holds a valve or cartridge firmly in place inside the faucet. When the faucet handle turns, the valve or cartridge rotates against the washer. A worn-out washer can cause the valve or cartridge to wear out the valve seat. This can be a source of leaks.

Washer

A flat ring or perforated material used to give tightness to a joint, to prevent leaking and to distribute pressure under the head of a nut or bolt. These come in a variety of types and can be rubber, leather or metal. They include the O-ring, faucet washers, and gaskets.

Rubber washers degrade over time. Worn-out rubber washers are the most common source for a leaky bathtub faucet. (If you don’t know what you might need to replace, you may want to have a variety pack on hand.)

How to Fix a Leaky 3-Hole (Compression) Bathtub Faucet

1. Turn the water off at the source.
2. Cover the drain with a cloth.
3. Pop off the caps with a flathead screwdriver. 
4. Remove the screw(s) beneath the cap(s)
5. Disassemble the “guts” of the faucet. Take out the cartridge or valve, the washer and valve seat.
6. Examine the washer. Is the rubber corroded, uneven or worn? If yes, replace it. (This is most likely the problem.)
7. Look at the inside of the valve seat. Is it corroded, uneven or worn? If yes, replace it.
8. Reassemble the parts.
9. Then turn on your water and check that the problem is fixed.

For step 3 above, if you know the problem is with either the hot or cold water line, you can just pop off one cap. But if you’re unsure, remove both caps.

How to Fix a Leaky 1-Hole (Swivel Handle) Bathtub Faucet

1. Turn off the water at the source.
2. Cover the drain with a cloth.
3. Remove the screw that’s on the side of the swivel handle with an Allen wrench.
4. Pull off the swivel handle.
5. Remove the nut with tongue and groove pliers.
6. Pull off metal sleeve, O-ring, clip and cartridge.
7. Inspect O-ring for corrosion and uneven surfaces.
8. Using a flashlight, inspect two washers inside the faucet for corrosion.
9. Use a flathead screwdriver to pop washers out of sockets.
10. Replace any eroded parts and reassemble by working through steps in reverse.
11. Turn on your water supply and test that the problem is fixed.

How to Fix Water Leaking From Caulk or Grout

If you’ve got cracks in caulking around the perimeter of your tub, or around hardware affixed to the wall, deck or floor, the fix is easy! Simply pull off the caulking and recaulk with a waterproof silicone.

1. Dry surface thoroughly.
2. Cut away old silicone by slicing horizontally along the top and bottom edges of the silicone.
3. Remove any remaining silicone with a flat-bladed utility scraper.
4. Spray all-purpose cleaner on seams.
5. Scrub with nylon brush to remove any remainder.
6. Wipe seams with Clorox disinfectant wipes. 
7. Let seams dry.
8. Squeeze a thin bead of silicone around cracks.
9. Run your finger on top of the silicone to fully press it into the adjoining surface.
10. Allow the silicone to dry a few hours. 

For number 8 above, you may or may not need a caulking gun. Certain caulking tubes are designed to give you control without a caulking gun. Also, be sure to purchase the right color of caulk to match your bathroom.

Also, if your moisture meter is telling you that there is damage inside the drywall or floor, that is another matter. Before you recaulk, you’ll need to replace damaged parts either yourself or by calling a carpenter or contractor.

You may be wise to use a caulk that is antimicrobial and will help prevent mold and mildew.

How to Fix Cracks in Tile Grout

1. Clean tile and dry thoroughly.
2. Use a grout saw to remove cracked (or moldy) tile grout. Always move saw in one direction.
3. Wear dust mask and use a vacuum to suck out any remaining chunks of grout.
4. Buy grout to match existing tile grout.
5. Use a margin trowel to spread new grout across tile.
6. Force grout into the joint with a rubber float at 45 degree angle to joint.
7. Wipe surface clean with a damp sponge.
8. In a few hours, buff off the haze on the tile with a clean towel.

How to Fix a Leaky Bathtub Overflow Drain

If your overflow drain is leaking, you will probably be able to fix the problem yourself. 

Check the silicone caulk around the drain itself. Does it need to be replaced? If yes, follow directions for fixing caulking above. If that’s not the issue then follow these steps:

1. Remove the cover on the overflow drain.
2. Check the rubber gasket behind the metal plate for corrosion. 
3. If the gasket needs to be replaced, angle the fat part of the gasket toward the bottom of tub.
4. When you put back the metal plate, be sure to tighten it completely.
5. If you have a metal drain plug, check for corrosion. You may need to reapply sealing putty to even surfaces. If this doesn’t work, you’ll need to replace the drain.

How to Fix a Leaky Bathtub Drain

The hole around the metal drain plug at the bottom of your tub can become uneven due to mineral deposits or corrosion. 

1. Remove the drain plug and feel the surface of the hole with your finger. 
2. If you notice cracks, file the surface so it’s even.
3. Are there holes? If so, fill with plumber’s sealing putty.
4. Reinstall drain plug and test that problem is fixed.

How to Fix a Cracked Bathtub

If there are cracks in the bathtub material itself, you can attempt to fill the cracks with waterproof putty to see if this fixes the problem.

1. Dry surface thoroughly.
2. Apply a bead of waterproof sealant to cracks.
3. Run a finger along the crack to press in sealant.
4. Allow to dry thoroughly and retest.

If you still have a leak, you’ll probably want to consider either a bathtub liner, bathtub refinishing or a new bathtub.

Bathtub Liner

A bathtub liner is a piece of acrylic that is molded to fit right over your existing bathtub. It must be installed by a plumber. However, if the fit isn’t perfect, water can pool between the original tub and the liner causing mold problems.

For much more about whether a bathtub liner is the right solution for you, be sure to read my indepth piece Are Bathtub Liners Any Good?

Bathtub Refinishing

You might also consider a professional bathtub refinisher. The refinisher will remove any mineral deposits on the bathtub surface, no matter what material your tub is made from, and this professional will also repair chips and cracks. Then the refinisher will tub with an acrylic coating.

New Bathtub

Finally, you may opt to buy a new tub. No matter what you decide, though, remember to factor in the cost of removing your old tub and installing the new tub when you compare possible solutions to your problem.

How to Fix Leaks in Valves and Pipes Under the Tub

This can be the most complicated type of leak to fix. The key is knowing the exact source of the problem. If you need to call a professional for help, being able to point to the source will certainly fast-track you to the solution. And if you are committed to DIY, do the following:

1. Check that valves with screw-on connections are tight.
2. If you have rusted valves or pipes, look for pinhole leaks. If found, replace the valves.
3. If old pipes were installed incorrectly, call a plumber for assistance.

Leaking Bathtub: Save Money by Finding the Source

Even if you need to hire a plumber in the end, it may be well worth your while to hunt down the source of the leak. Since most plumbers are paid by the hour, you’ll save a good deal of time. If you’ve discovered the problem, you can tell the plumber over the phone and the plumber can arrive with parts on hand.

Then again, once you discover the source of your leaking tub, you’ll be able to see how complicated the fix will be. At that point, you may want to challenge yourself to DIY the solution. After all, there’s nothing more satisfying than learning a new skill, while you fix a problem in your home.

Be sure to reward yourself with a relaxing soak in the bathtub! See 21 Relaxing Bath Ideas to Take Me-Time to the Next Level. You certainly deserve it!

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