What a Faucet Cartridge Is and Why You Replace It

A cartridge is the part inside your faucet handle that controls water temperature and flow. When you turn the handle, you are moving the cartridge, not the water directly. Over time—usually after five to ten years—the cartridge wears out, and your faucet will drip, leak, or stop responding to the handle. Replacing the cartridge fixes the problem without replacing the entire faucet.

The cartridge sits hidden behind your handle. You cannot see it without taking the faucet apart, but you can feel when it has failed: the handle becomes stiff, water leaks from the spout even when the handle is off, or the temperature does not change when you adjust the handle. A new cartridge costs between $15 and $75 depending on the brand, and the job takes about 30 minutes if you have the right cartridge model.

Key Takeaways

  • You must identify your faucet brand and model before buying a cartridge, because cartridges are not universal and a wrong one will not fit.
  • Turn off the water supply under the sink before you start, and turn on the faucet to release pressure in the lines.
  • The cartridge sits under the handle; you remove the handle first by prying off a cap and unscrewing a screw, then pull out the old cartridge with pliers.
  • Insert the new cartridge in the same position as the old one, reassemble the handle, and test for leaks before you turn the water back on fully.
  • If water still leaks after replacement, the problem may be the valve seat or O-rings, which require a different repair.

Identify Your Faucet Brand and Model Before You Buy

The cartridge you need depends on who made your faucet. Moen, Delta, Kohler, and Pfister each make different cartridges, and they do not interchange. If you buy the wrong one, it will not fit, and you will have wasted money and time.

Look under your sink or on the faucet body itself for the brand name. It is usually stamped or printed on the metal. If you cannot find it, take a photo of the faucet and bring it to a hardware store, or call the store's plumbing department and describe the handle style and spout shape. Once you know the brand, search online for "[brand] faucet cartridge replacement" or look at the faucet manual if you have it. Write down the exact cartridge model number before you go to the store or order online.

Turn Off the Water and Release the Pressure

Under your sink, you will see two shut-off valves—one for hot water and one for cold. Turn both clockwise until they stop. Do not force them; they should turn smoothly. If they are stuck or will not turn, you may need to turn off the main water supply to the house instead, which is usually in the basement or outside.

After you close the valves, turn on the faucet handle and let water run for a few seconds. This releases the pressure in the lines so water does not spray when you open the faucet. Leave the handle in the on position while you work.

Remove the Handle and Expose the Cartridge

Most faucet handles have a small cap or plug on top or on the side. Use a flathead screwdriver or a plastic pry tool to gently pop off this cap—do not use a metal screwdriver directly on the cap if it is decorative, because you will scratch it. Underneath the cap is a screw. Remove this screw with a Phillips screwdriver and set it somewhere safe.

Pull the handle straight up and away from the faucet. It should come off easily; if it does not, wiggle it gently side to side as you pull. Once the handle is off, you will see the cartridge body, which looks like a cylinder or a flat piece with a notch or slot on top. Some faucets have a decorative collar or collar nut around the cartridge; if yours does, use an adjustable wrench to turn it counterclockwise and remove it.

Pull Out the Old Cartridge

The cartridge is held in place by friction and sometimes by a small clip or retaining nut. Look for a clip on the side of the cartridge body—if you see one, use needle-nose pliers to pull it straight out and set it aside. If there is a retaining nut (a small hexagonal nut on top of the cartridge), use a socket wrench or adjustable wrench to turn it counterclockwise and remove it.

Grip the cartridge body with adjustable pliers or a cartridge puller tool (a specialized tool you can rent or buy for $10 to $20). Turn the pliers handle to tighten the grip, then pull straight up with steady, even pressure. The cartridge should slide out. If it is stuck, do not force it—spray a penetrating oil like WD-40 around the base, wait 10 minutes, and try again. Once the cartridge is out, you may see rubber O-rings around the base; note their position or take a photo so you can put them back in the same spot.

Install the New Cartridge and Reassemble

Before you insert the new cartridge, check the orientation. Most cartridges have a notch, slot, or flat side on top that must align with a matching notch in the faucet body. Look at the old cartridge or the faucet opening to see which way it should go. Slide the new cartridge straight down into the opening, aligning the notches. It should fit snugly but not require force.

If the old cartridge had a retaining nut or clip, install the new one the same way: put the clip back in place or screw the nut back on and tighten it by hand, then snug it with a wrench. Do not over-tighten. Replace the decorative collar if there was one, then slide the handle back onto the cartridge, making sure the notch on the handle aligns with the notch on the cartridge. Screw the handle screw back in and replace the cap.

Test for Leaks and Turn the Water Back On

Before you turn the water supply back on, turn the handle to the off position. Then slowly turn the shut-off valves under the sink counterclockwise to turn the water back on. Turn on the faucet and let water run for 10 to 15 seconds to flush out any debris from the lines. Check the spout and the base of the faucet for leaks. A small drip from the spout is normal for the first minute; if it continues after a minute, the cartridge may not be seated correctly.

If the faucet still drips after the cartridge is replaced, the problem may be the valve seat (the surface the cartridge seals against) or the O-rings. These require a different repair: the valve seat may need to be cleaned or replaced, and the O-rings may need to be removed and reseated. If you are not comfortable doing this, a plumber can handle it for $100 to $200.

Common Mistakes to Avoid

The most common mistake is buying the wrong cartridge model. Take the time to identify your faucet brand correctly before you buy. The second mistake is forcing the cartridge out when it is stuck; use penetrating oil and patience instead of brute force, or you may damage the faucet body.

A third mistake is not aligning the cartridge notch correctly when you reinstall it. If the notches do not line up, the cartridge will not seat properly and the faucet will leak or the handle will not turn smoothly. Check the alignment before you push the cartridge all the way in. Finally, do not forget to turn off the water supply before you start—this is the easiest step to skip and the most important one.

Frequently Asked Questions

How do I know if my faucet has a cartridge or a different type of valve?

Single-handle faucets almost always use a cartridge. Two-handle faucets may use cartridges, compression valves, or ball valves. If you turn a single handle up and down to control temperature and flow, you have a cartridge faucet. If you have two handles and they turn in a circle, you likely have compression valves instead.

Can I replace just the O-rings instead of the whole cartridge?

Yes, if the cartridge itself is not damaged and the only problem is a leaking O-ring. You can buy an O-ring kit for $5 to $10, remove the cartridge, slide off the old O-rings, and slide on new ones. This is cheaper than a full cartridge replacement, but it only works if the cartridge body is not cracked or worn.

What if the cartridge is stuck and will not come out?

Spray penetrating oil around the base of the cartridge and wait 15 to 30 minutes. Try again with pliers, pulling straight up with steady pressure. If it is still stuck, you can try tapping the pliers handle gently with a hammer to help break the seal, but do not hit hard. If it remains stuck after this, a plumber may need to remove the entire faucet body to access the cartridge from underneath.

Do I need to turn off the water at the main if the shut-off valves under the sink do not work?

Yes. If the shut-off valves will not turn or are leaking, turn off the main water supply to the house. This is usually a valve in the basement, crawl space, or outside near the foundation. If you cannot find it, call your water company and ask where the main shut-off is located.

How long does a new cartridge last?

A new cartridge typically lasts five to ten years, depending on water hardness and how often the faucet is used. Hard water can shorten the life of a cartridge because mineral buildup wears it out faster. If your water is very hard, you may want to install a water softener to extend the life of your cartridge and other plumbing fixtures.