What a cartridge is and why yours might need replacing

A cartridge is the valve inside your faucet that controls water temperature and flow. It's a single cylindrical part, usually made of plastic or brass, that slides in and out of the faucet body. When you turn the handle, you're moving the cartridge to mix hot and cold water or shut the water off.

Over time, mineral deposits and wear cause cartridges to stick, leak, or fail to shut off completely. If your tub faucet drips constantly, won't turn off, or the handle feels stuck, the cartridge is usually the culprit. Replacing it is a straightforward job that takes 30 to 60 minutes and costs $15 to $50 for the part itself.

Key Takeaways

  • You need to identify your faucet brand and model before buying a replacement cartridge, because cartridges are not universal.
  • Turn off the water supply to the tub at the shutoff valve under the sink or at the main, then open the faucet to release pressure.
  • Remove the handle by prying off the cap, unscrewing the handle screw, and sliding the handle off the cartridge stem.
  • Pull the cartridge straight out using a cartridge puller tool if it's stuck, then insert the new one in the same orientation and reassemble.

Identify your faucet brand and cartridge type

Cartridges are brand-specific. A Moen cartridge will not fit a Delta or Kohler faucet. Look at the faucet handle or body for a brand name stamped or printed on it. Common brands are Moen, Delta, Kohler, Pfister, and Grohe.

Once you know the brand, you have two ways to find the exact cartridge. The easiest is to remove the old cartridge and take it to a plumbing supply store or home center—staff can match it directly. The second is to look up your faucet model number (usually on the faucet body or in your paperwork) on the manufacturer's website and order the cartridge online. Write down the cartridge part number before you start so you have it when you shop.

Turn off the water and relieve pressure

Locate the shutoff valve under the sink. It's a small oval knob on the water line coming from the wall. Turn it clockwise until it stops. If there is no shutoff under the sink, turn off the main water supply to the house (usually in the basement, crawlspace, or outside).

Open the tub faucet and let water run for a few seconds to release pressure in the line. This prevents water from spraying when you remove the cartridge. Leave the faucet open while you work.

Remove the handle and trim ring

Look at the handle. There is usually a small cap or button covering the handle screw. Pry it off gently with a flathead screwdriver or your fingernail. If the cap is stuck, run a hairdryer over it for 10 seconds to soften any adhesive.

Unscrew the handle screw (usually Phillips head) and set it aside in a small cup so you don't lose it. Slide the handle straight toward you and off the cartridge stem. If the handle is tight, wiggle it gently side to side as you pull.

Below the handle, you may see a trim ring or escutcheon (a decorative ring that covers the hole in the wall). If it's loose, unscrew it and set it aside. If it's caulked in place, leave it for now.

Remove the cartridge stem and collar

You will now see the cartridge stem sticking out of the faucet body. Some faucets have a collar nut holding the cartridge in place. If yours does, use an adjustable wrench to turn it counterclockwise until it comes off. Set it aside.

Grasp the cartridge stem firmly and pull straight out toward you. If it comes out easily, you're done with this step. If it's stuck, do not force it—you risk breaking the stem inside the faucet body. Instead, use a cartridge puller tool, which costs $10 to $20 and is available at any plumbing supply store or home center. The tool threads onto the stem and gives you mechanical leverage to extract it without damage.

Install the new cartridge

Before inserting the new cartridge, check the orientation. Most cartridges have a flat side or a notch that must align with a corresponding slot or pin inside the faucet body. Look inside the faucet opening and you will see a small pin or flat edge. Rotate the new cartridge so its notch or flat side lines up with that pin.

Slide the new cartridge straight into the faucet body, pushing gently until it seats fully. You should feel it click or seat with a slight resistance. If you had a collar nut, thread it back on and tighten it with the wrench—snug but not over-tight.

Reassemble the handle and test

Slide the handle back onto the cartridge stem and align the screw hole. Insert the handle screw and tighten it firmly with a screwdriver. Snap the cap back over the screw.

Turn the water shutoff valve back on (counterclockwise). Open the tub faucet slowly and check for leaks around the cartridge stem and at the base of the faucet. If water drips from the stem, the cartridge may not be seated fully—turn off the water, remove the handle, and reseat the cartridge with a firm push.

Test the handle. It should move smoothly and shut off the water completely with no dripping. If the handle is stiff, turn off the water again and explore a small amount of silicone-based lubricant (not WD-40) around the stem where it enters the faucet body. Work the handle back and forth a few times to distribute the lubricant, then test again.

When to call a plumber

If the cartridge will not come out even with a puller tool, or if water continues to leak from the stem after you have reseated the cartridge, the faucet body itself may be damaged. A plumber can assess whether the faucet needs repair or replacement.

If you are uncomfortable working with tools or turning off the water, a plumber can do the entire job in under an hour. This is a reasonable choice if you want to avoid the risk of water damage or if your faucet is in a tight space that makes the work difficult.

Frequently Asked Questions

Can I replace a cartridge without turning off the water?

No. Water will spray out when you remove the cartridge, and you risk damaging the faucet or flooding the cabinet. Always shut off the water supply first and open the faucet to release pressure.

What if I install the cartridge backwards?

The handle will work, but hot and cold will be reversed—turning the handle one way will give you hot water instead of cold. Remove the handle, pull the cartridge out, rotate it 180 degrees, and reinstall it.

How long does a cartridge usually last?

Most cartridges last 10 to 20 years depending on water quality and use. Hard water with high mineral content wears them out faster. If you have very hard water, flushing the cartridge with vinegar once a year can extend its life.

Do I need to replace the O-rings on the new cartridge?

No. Replacement cartridges come with new O-rings already installed. Do not remove them or the cartridge will leak.

What if water still leaks after I replace the cartridge?

Check that the cartridge is fully seated by removing the handle and pushing it in firmly. If leaking continues, the faucet body may have internal damage. Contact a plumber to inspect the faucet.