What a cartridge is and why yours might need replacing

A cartridge is the valve inside your faucet that controls water flow and temperature. In a double-handle faucet, you have two cartridges—one under each handle. When a cartridge wears out, you'll notice water dripping from the spout even when the handles are fully closed, or the handle becomes stiff and hard to turn. Replacing the cartridge is usually faster and cheaper than replacing the entire faucet.

The cartridge itself is a small cylindrical part, typically 2 to 4 inches long, made of plastic or brass. It contains springs, seals, and a valve stem that wear down over time from constant use. Hard water, sediment, and mineral buildup can speed up this wear. The good news: you don't need to shut off water to the whole house, and the job takes about 30 minutes once you have the right cartridge.

Key Takeaways

  • You need to identify your faucet brand and model before buying a replacement cartridge, because cartridges are not universal across brands.
  • Turn off the water supply to that specific faucet using the shutoff valves under the sink, not the main water valve.
  • Remove the handle by prying off the decorative cap, unscrewing the handle screw, and pulling the handle straight up and off.
  • Use a cartridge puller tool (a specialized wrench you can rent or buy for $10–$30) to remove the old cartridge, because it is usually too tight to remove by hand.
  • Install the new cartridge by sliding it straight in, making sure the alignment notch on the cartridge matches the slot in the faucet body.

Identify your faucet brand and find the correct cartridge

Before you buy anything, you need to know what brand and model faucet you have. Look under the sink at the faucet body itself—most brands stamp their name there. Common brands include Moen, Delta, Kohler, Pfister, and Grohe. If you can't find a stamp, look at the handles or spout for a logo.

Once you know the brand, search online for "[brand name] cartridge replacement" or check the faucet manual if you still have it. You can also take a photo of the faucet and bring it to a plumbing supply store; staff there can usually match it. Cartridges cost between $15 and $60 depending on the brand. Buying the wrong cartridge will not fit, so take the time to confirm the model number before checkout.

If your faucet is more than 15 years old and you cannot identify the brand, consider calling a plumber. Older faucets sometimes use cartridges that are no longer made, and replacement may not be possible without replacing the entire faucet.

Turn off the water supply and drain the lines

Look under the sink for two small shutoff valves—one on the hot water line and one on the cold water line. They usually have a small handle or knob. Turn both valves clockwise until they stop. You should feel resistance, but do not force them; they can break if you turn too hard.

After shutting off the valves, turn on the faucet handle to release any remaining water pressure in the lines. Let the water run for a few seconds, then turn the handle back off. This step prevents water from spraying out when you remove the cartridge. If water continues to drip from the spout after you've shut off both valves, the shutoff valves themselves may be worn out—in that case, you may need a plumber to replace them first.

Remove the handle and expose the cartridge

Look at the top of the handle where it meets the faucet body. You'll see a small decorative cap, usually made of plastic or metal. Use a flat-head screwdriver or a plastic pry tool to gently pop this cap off. Do not use a metal screwdriver directly on a finished cap, as it can scratch the chrome or paint.

Underneath the cap is a single screw. Remove this screw with a Phillips-head screwdriver and set it aside in a small container so you don't lose it. Now grab the handle and pull it straight up and away from the faucet body. It should come free without much force. If it's stuck, wiggle it gently side to side while pulling—do not twist it, as that can break the handle.

Once the handle is off, you'll see the cartridge body underneath. It's a cylindrical piece, usually with a flat top and a notch or slot on one side. This is what you're replacing.

Remove the old cartridge with a cartridge puller

The cartridge is held in place by friction and is almost always too tight to remove by hand. You need a cartridge puller—a specialized wrench designed for this job. Pullers are brand-specific, so when you buy your replacement cartridge, buy the puller for that brand too. Moen, Delta, and Kohler each make their own. A puller costs $10 to $30 and can be rented from some plumbing supply stores for $5 to $10 if you don't want to buy one.

Fit the puller over the cartridge stem (the part sticking up from the top). The puller has a handle or knob that you turn clockwise. As you turn, the puller grips the cartridge and pulls it straight up and out of the faucet body. This usually takes steady pressure—turn slowly and do not jerk. Once the cartridge is out, set it aside.

If you cannot get the cartridge to budge even with the puller, the cartridge may be corroded or stuck from mineral buildup. Spray the cartridge with white vinegar and let it sit for 15 minutes, then try again. If it still won't move, call a plumber rather than forcing it—forcing can crack the faucet body.

Install the new cartridge and reassemble

Before you insert the new cartridge, look at the faucet body where the cartridge sits. You'll see a small slot or notch on one side. Now look at the new cartridge—it has a corresponding flat edge or notch. These must align when you insert the cartridge. Slide the new cartridge straight down into the faucet body, making sure the notch on the cartridge lines up with the slot in the body. Push it down firmly until it sits flush with the top of the faucet.

Once the cartridge is seated, replace the handle by sliding it back onto the cartridge stem and pushing it down until it sits flush. Screw the handle screw back in and tighten it with a Phillips-head screwdriver. Do not over-tighten—snug is enough. Pop the decorative cap back on by pressing it down until it clicks.

Turn the shutoff valves back on by turning them counterclockwise. Turn on the faucet and check for leaks around the handle and at the base of the spout. If water drips from the spout when the handle is fully closed, the new cartridge may be installed backwards or upside down. Turn off the water, remove the handle, and check that the cartridge notch is aligned correctly with the faucet body slot.

Test the faucet and troubleshoot common issues

Run hot and cold water through the faucet and check that both handles move smoothly and that the water temperature changes as expected. The handle should not feel stiff or require excessive force to move. If the handle is still hard to turn after the cartridge replacement, you may have installed the cartridge backwards—remove it and flip it 180 degrees.

If water still drips from the spout after you've turned the handle fully off, the new cartridge may be defective. This is rare but does happen. Turn off the water, remove the handle, and check that the cartridge is seated all the way down and the notch is aligned. If it is, the cartridge itself may be faulty and should be returned to the store for a replacement.

If water leaks from under the handle where it meets the faucet body, the handle screw may be loose. Tighten it a quarter turn and test again. If the leak continues, the cartridge may not be fully seated—remove the handle, push the cartridge down harder, and reinstall the handle.

When to call a plumber instead

Call a plumber if the shutoff valves under the sink do not turn off the water completely, or if water continues to drip from the spout even after you've installed a new cartridge and confirmed it's aligned correctly. A plumber can replace faulty shutoff valves or diagnose whether the faucet body itself is damaged and needs replacement.

Also call a plumber if you cannot identify your faucet brand or model, or if the faucet is very old and the cartridge is no longer made. Attempting to force an incompatible cartridge into the faucet can crack the faucet body, which is expensive to repair.

Frequently Asked Questions

Can I replace just one cartridge in a double-handle faucet?

Yes. Each handle has its own cartridge, and you can replace one without touching the other. If only one handle is leaking or stiff, replace only that cartridge. If both are leaking, you'll need to replace both, but you can do them one at a time.

What if I turn on the water and nothing comes out?

You may have installed the cartridge backwards or upside down. Turn off the water, remove the handle, and check that the flat edge or notch on the cartridge aligns with the slot in the faucet body. Remove the cartridge, flip it 180 degrees, and reinstall it.

Do I need to turn off the main water valve to the house?

No. The shutoff valves under the sink are sufficient. Using the main valve is unnecessary and can cause problems if you forget to turn it back on. Use only the hot and cold shutoff valves under the sink.

How long does a faucet cartridge usually last?

Most cartridges last 5 to 10 years with normal use. Hard water and high water pressure can shorten this. If your cartridge fails after less than a year, the replacement may be defective—return it to the store.

Can I reuse the old cartridge if the new one doesn't fit?

No. Once a cartridge is removed, the seals are compromised and it will leak. Always install a new cartridge. If the new one does not fit, you bought the wrong model—return it and get the correct one for your faucet brand.