A leaking faucet might not seem like a major plumbing problem at first. Maybe it is just a slow drip from the bathroom sink, a small puddle around the kitchen faucet, or a handle that leaks only when the water is running.
But even a small faucet leak can waste water, increase your utility bill, and point to a part inside the faucet that is wearing out. The good news is that most faucet leaks are caused by a handful of common problems. Once you understand what causes a faucet to leak, it becomes easier to know whether you can handle the repair yourself or whether it is time to call a plumber.
Common Causes of a Leaky Faucet
Faucets have several small parts that work together to control water flow and create a tight seal when the water is turned off. Over time, those parts can wear down, loosen, corrode, or stop sealing properly.
Here are some of the most common reasons your faucet may be leaking.
1. Worn-Out Washers
A worn-out washer is one of the most common causes of a dripping faucet, especially in compression-style faucets.
The washer is a small rubber part that presses against the valve seat when you turn the faucet off. This creates a seal that stops water from flowing. Each time you use the faucet, the washer rubs against other parts inside the fixture. Over time, that friction can wear it down.
When the washer becomes cracked, stiff, loose, or misshapen, it can no longer create a proper seal. As a result, water can continue dripping from the spout even after the handle is turned off.
A washer can also leak if it was installed incorrectly or if the wrong size washer was used during a previous repair.
2. Damaged O-Rings
An O-ring is a small rubber ring that helps seal parts inside the faucet. If your faucet is leaking around the handle or near the base of the spout, a worn or damaged O-ring may be the problem.
O-rings are common in cartridge faucets and some single-handle faucets. Over time, they can dry out, crack, loosen, or wear down from regular use. Once that seal fails, water can seep out around the handle or base.
This type of leak may start small, but it can get worse if ignored. Replacing the O-ring is often a simple repair, but the faucet may need to be taken apart to confirm that the O-ring is the actual cause.
3. Corroded Valve Seat
The valve seat connects parts of the faucet to the spout and helps control water flow. If it becomes corroded, water may leak from the spout even when the faucet is off.
Corrosion often happens because of mineral buildup, especially in homes with hard water. Over time, minerals and sediment can collect around the valve seat, damaging the surface and preventing the faucet from sealing properly.
A corroded valve seat can sometimes be cleaned, but if the damage is severe, the part may need to be repaired or replaced. In some cases, corrosion inside the faucet is a sign that the fixture itself is nearing the end of its life.
4. Faulty Faucet Cartridge
Many modern faucets use a cartridge to control water flow and temperature. When the cartridge works properly, it opens and closes smoothly as you move the handle. But if the cartridge becomes worn, clogged, cracked, or damaged, the faucet may start to leak.
A faulty cartridge can cause several issues, including:
- Dripping from the spout
- Leaking around the handle
- Difficulty turning the faucet on or off
- Trouble controlling hot and cold water
- Uneven or inconsistent water flow
Cartridge problems are common in both kitchen and bathroom faucets. The repair usually involves removing the handle, taking out the old cartridge, and installing a matching replacement.
5. Loose Faucet Parts
Sometimes a faucet leaks simply because something inside it has loosened. Faucet handles, packing nuts, adjusting rings, stems, and other small components can shift over time with regular use.
When these parts are loose, water may escape around the handle, base, or spout. You may also notice that the faucet handle feels wobbly, stiff, or less secure than it used to.
In some cases, tightening the right part can stop the leak. However, if the part is damaged, stripped, or corroded, tightening alone may not be enough.
6. High Water Pressure
High water pressure can put extra stress on your faucet and plumbing system. If the pressure is too strong, it can force water past seals, washers, and other internal parts.
One clue that water pressure may be involved is a leak that happens only at certain times. For example, the faucet might drip at night, when water demand in the home or neighborhood is lower and pressure is higher.
High water pressure can affect more than one fixture, so it is worth taking seriously. Left alone, it can contribute to leaks, worn plumbing parts, and damage throughout the system.
7. Mineral Buildup
Mineral buildup from hard water can affect washers, cartridges, valve seats, aerators, and other faucet parts. As minerals collect, they can block water flow, damage seals, and keep moving parts from working the way they should.
Signs of mineral buildup include white or chalky residue around the faucet, reduced water flow, uneven spray, or a faucet that feels harder to operate.
Cleaning may help in some cases, but if the buildup has damaged internal parts, those parts may need to be replaced.
8. Worn Seals
Faucets rely on seals to keep water contained inside the fixture. Like washers and O-rings, these seals can wear out over time. When they fail, leaks may appear around the spout, handle, or base.
Seals may wear faster if the faucet is used heavily, exposed to hard water, or affected by high water pressure. A plumber can inspect the faucet and determine whether the leak is coming from a replaceable seal or a larger issue inside the fixture.
9. A Problem Under the Sink
Not every “faucet leak” actually comes from the faucet itself. Sometimes water appears near the faucet, but the real problem is under the sink.
Possible causes include:
- Loose supply line connections
- Damaged water supply lines
- Leaking shutoff valves
- Drain leaks
- Worn fittings
- Cracked pipes or connections
If you see water pooling in the cabinet below your sink, do not assume the faucet is the only issue. Leaks under the sink can cause cabinet damage, mold growth, and flooring problems if they are not fixed quickly.
How to Tell Where Your Faucet Is Leaking From
The location of the leak can give you clues about the cause.
If water is dripping from the spout, the issue may be a worn washer, faulty cartridge, damaged seal, or corroded valve seat.
If water is leaking around the handle, the problem may be a damaged O-ring, loose packing nut, worn cartridge, or internal seal issue.
If water is collecting around the base of the faucet, the O-ring or base seal may be worn.
If water is pooling under the sink, the issue may be with the supply lines, shutoff valves, drain assembly, or other plumbing connections.
This is why it is important to look closely before assuming the faucet needs to be replaced. In many cases, a small part is responsible for the leak.
Can You Fix a Leaky Faucet Yourself?
Some leaky faucets can be fixed with basic tools and replacement parts. If the problem is a worn washer, O-ring, or cartridge, a handy homeowner may be able to make the repair.
Before attempting a faucet repair, always turn off the water supply under the sink. Then open the faucet to release any remaining water pressure. It is also a good idea to cover the drain so small screws or parts do not fall in.
However, DIY faucet repair is not always simple. Different faucet types use different parts, and replacement pieces need to match your specific faucet. If a part is installed incorrectly, the leak may continue or get worse.
When to Call a Plumber for a Leaky Faucet
You should call a plumber if:
- You cannot identify where the leak is coming from
- The faucet keeps leaking after replacing parts
- There is corrosion inside the faucet
- Water is leaking under the sink
- The faucet is old or damaged
- You suspect high water pressure
- Multiple fixtures are leaking
- You are not comfortable taking the faucet apart
A plumber can diagnose the issue, replace the correct parts, and check for related plumbing problems that may not be obvious.
Should You Repair or Replace a Leaky Faucet?
In many cases, a leaky faucet can be repaired. Replacing a washer, O-ring, cartridge, or seal is often more affordable than installing a new fixture.
However, replacement may be the better option if the faucet is badly corroded, outdated, difficult to repair, or leaking from multiple areas. If you have already repaired the faucet several times and it keeps leaking, a new faucet may save you time and frustration.
A professional plumber can help you decide whether repair or replacement makes more sense.
Don’t Ignore a Leaking Faucet
A dripping faucet may seem minor, but it is usually a sign that something inside the fixture is worn, loose, or damaged. The longer you wait, the more water you may waste and the more likely the problem is to get worse.
Whether the cause is a worn washer, damaged O-ring, faulty cartridge, corroded valve seat, or water pressure issue, fixing the leak early can help protect your plumbing and prevent unnecessary water waste.
If your faucet will not stop dripping, leaks around the handle, or leaves water under the sink, schedule faucet repair with a trusted plumber. A quick repair today can help prevent a bigger plumbing problem tomorrow.
