What a faucet cartridge is and why you need to replace it

A faucet cartridge is the part inside your faucet that controls water flow and temperature when you move the handle. It looks like a small cylinder, usually plastic or brass, and sits hidden inside the faucet body. When a cartridge wears out, you get a dripping faucet, water that won't shut off completely, or handles that stick and won't move smoothly.

Replacing the cartridge yourself takes about 30 minutes and costs $15 to $50 for the part—far less than calling a plumber. The job requires no special skills, just the right cartridge model for your faucet and a few basic tools you likely already own.

Key Takeaways

  • You must identify your faucet brand and model before buying a replacement cartridge, because cartridges are not universal and one brand will not fit another.
  • Turn off the water supply under the sink before you start, or shut off the main water valve if you cannot find the shutoff valves.
  • Remove the handle by prying off a decorative cap, then unscrew the handle screw and lift the handle straight up and off.
  • Pull out the old cartridge using a cartridge puller tool (a $10 to $20 rental or purchase from any hardware store), then slide the new cartridge in and reassemble in reverse order.
  • Test for leaks at the connection points under the sink before you consider the job finished.

Identify your faucet brand and model before you buy

The cartridge you need depends entirely on your faucet brand. Moen cartridges do not fit Kohler faucets, and Pfister cartridges do not fit Delta. If you buy the wrong one, it will not slide into the faucet body and you will have wasted money.

Look under the sink or on the faucet body itself for a brand name stamped or printed on the metal. Common brands are Moen, Delta, Kohler, Pfister, and Grohe. Once you know the brand, take a photo of the faucet or write down the model number if you can find one. Bring this information to the hardware store, or search online for "[brand name] faucet cartridge" to find the exact part number. Many stores can look up the cartridge by brand and model while you wait.

Turn off the water supply and prepare your workspace

Look under the sink for two shutoff valves—one for hot water and one for cold. Turn both clockwise until they stop. If you cannot find shutoff valves under your sink, you will need to turn off the main water valve for your home, usually located in the basement, crawl space, or outside near the water meter. Turn it clockwise until it stops.

Once the water is off, turn on the faucet handle to release any remaining water pressure in the lines. Place a towel under the sink to catch any water that drips from the connections. Have a small bucket or cup nearby as well—cartridge removal can release a small amount of trapped water.

Remove the handle and decorative trim

Look for a small decorative cap on top of or behind the faucet handle. This cap usually snaps on and covers the handle screw. Use a flat-head screwdriver or a plastic pry tool to gently pop it off. Do not use a metal screwdriver directly on the cap if it is chrome or polished—wrap the screwdriver tip in a cloth first to avoid scratching.

Once the cap is off, you will see a screw. Use a Phillips-head screwdriver to unscrew it, turning counterclockwise. Keep the screw in a safe place—it is small and straightforward to lose. Lift the handle straight up and off the faucet. If it feels stuck, wiggle it gently side to side as you pull. Do not force it or you may crack the handle.

Below the handle, you may see a decorative collar or trim ring. Some faucets have one, some do not. If yours does, it usually unscrews by turning it counterclockwise by hand, or it may straightforward pull straight up. Set it aside with the handle.

Remove the old cartridge with a cartridge puller

You will now see the cartridge itself—a cylindrical part sticking up from the faucet body. Cartridges are designed to pull straight up and out, but they often stick from mineral buildup or corrosion. Pulling by hand usually will not work and can damage the cartridge or the faucet.

A cartridge puller is a straightforward tool that grips the cartridge and pulls it straight up with mechanical advantage. You can rent one from most hardware stores for $5 to $10, or buy one for $15 to $25. It looks like a small metal claw with a handle. Follow the tool's instructions—typically, you slide the claw around the cartridge stem, tighten a bolt to lock it in place, and then turn the handle to pull the cartridge up and out. This usually takes steady pressure, not sudden force.

Once the cartridge is out, you may see a small brass or plastic piece underneath called a cartridge seat or cartridge body. Leave it in place unless it is visibly cracked or damaged. If you remove it, you will need to reinstall it before the new cartridge goes in.

Install the new cartridge and reassemble

Before you insert the new cartridge, check the orientation. Most cartridges have a small notch or flat edge on the stem that must align with a matching notch or pin inside the faucet body. Look inside the faucet opening and locate this alignment feature. Slide the new cartridge in slowly, making sure the stem aligns with the notch. Push it down firmly until it seats completely—you should feel it click or settle into place.

Now reassemble in reverse order. If you removed a decorative collar, screw it back on by turning clockwise. Slide the handle back onto the cartridge stem and insert the screw. Tighten the screw by turning clockwise, but do not over-tighten—just snug enough that the handle does not wiggle. Snap the decorative cap back on over the screw.

Turn the water supply back on by turning the shutoff valves counterclockwise. Turn on the faucet and let water run for 10 to 15 seconds to flush out any air in the lines. Check under the sink for leaks at the shutoff valves and at the faucet base. If you see drips, turn the water off and tighten the connection slightly with a wrench. If the faucet still drips from the spout after 30 minutes of use, the new cartridge may not be seated correctly—turn off the water and reseat it by pushing down firmly.

Common mistakes to avoid

The most common mistake is buying the wrong cartridge because you did not verify the brand first. Take the extra five minutes to confirm the brand before you leave the store. Another frequent error is forcing the old cartridge out without a puller, which can crack the faucet body or strip the cartridge stem and make removal impossible.

Do not forget to turn off the water supply before you start—many people skip this step and end up with water spraying everywhere when they remove the cartridge. Also, do not over-tighten the handle screw when you reassemble. The screw only needs to be snug; over-tightening can crack the handle or strip the screw hole.

Finally, if the new cartridge does not slide in smoothly, stop and check the alignment. Forcing a misaligned cartridge can damage both the cartridge and the faucet body. If it truly will not go in after checking alignment, the cartridge may be the wrong model—verify the part number again before proceeding.

Frequently Asked Questions

Do I need a cartridge puller or can I just pull the cartridge out by hand?

Most cartridges will not budge by hand alone because mineral deposits and corrosion lock them in place. Pulling hard by hand risks breaking the cartridge stem or damaging the faucet. A cartridge puller costs $10 to $25 to buy or $5 to $10 to rent and makes the job safe and quick. It is worth the cost.

What if water keeps dripping from the spout after I install the new cartridge?

The cartridge is probably not seated all the way down. Turn off the water, remove the handle, and push the cartridge down firmly until you feel it click or settle. Reassemble and test again. If it still drips, the cartridge may be the wrong model—double-check the part number against your faucet brand and model.

Can I replace a cartridge without turning off the water?

You can, but water will spray out when you remove the old cartridge. If you must work without shutoff valves, have towels and a bucket ready, and work quickly. Turning off the water takes two minutes and prevents mess and waste, so it is worth doing if you can.

How do I know which shutoff valve is hot and which is cold?

The shutoff on the left side of the pipe (when facing the sink) is usually hot water, and the one on the right is usually cold. If you are unsure, turn off both. You only need one off to work on the cartridge, but turning off both is safer and prevents accidental hot water exposure.

What if the decorative cap will not pop off?

Try using a plastic pry tool or the edge of a plastic credit card instead of a screwdriver—metal can scratch. Work around the edge of the cap gently rather than forcing one spot. If it still will not budge, it may be glued on. Soak the area with warm water for a few minutes to soften any adhesive, then try again.