What a cartridge does and why you need to replace it

A cartridge is the part inside your faucet that controls water flow and temperature. When you turn the handle, you are moving the cartridge. Over time — usually five to ten years — the rubber seals inside wear out, and the cartridge starts to leak or becomes stiff to turn. Replacing it stops the drip and restores smooth operation without replacing the entire faucet.

Most single-handle faucets use a cartridge. Two-handle faucets use cartridges too, one in each handle. The cartridge itself costs between $15 and $75 depending on the brand. The job takes 30 minutes to an hour if you have the right cartridge and basic tools.

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 or at the main shutoff before you start, or you will have water spraying everywhere.
  • Most cartridges come out by removing the handle, then the decorative cap, then unscrewing a single bolt that holds the cartridge in place.
  • Push the old cartridge straight up and out, then slide the new one in the same way, making sure the alignment tab matches the slot in the faucet body.
  • If the cartridge does not turn smoothly after reassembly, you may have installed it backwards — remove it and flip it 180 degrees.

Identify your faucet brand and model number

The cartridge you need depends entirely on your faucet brand. Moen cartridges do not fit Kohler faucets, and Pfister cartridges do not fit either. Look under the sink or on the faucet body itself for a brand name stamped or printed on the metal. Common brands are Moen, Kohler, Delta, Pfister, and Grohe.

Once you know the brand, look for a model number. It is usually on a sticker under the sink, on the faucet spout, or on the escutcheon (the decorative ring around the base). Write down the full model number. Take a photo of it with your phone. When you go to the hardware store or search online, give the cashier or search engine both the brand and the model number. The staff can then pull the exact cartridge that fits your faucet.

If you cannot find a model number, bring the old cartridge with you to the store after you remove it. The staff can match it by sight.

Turn off the water and drain the lines

Look under the sink for two shutoff valves, one on the hot line and one on the cold line. They are usually oval knobs or small levers on the copper or plastic pipes. Turn both clockwise until they stop. If you cannot find shutoff valves under the sink, locate the main water shutoff for your house — usually in the basement, crawl space, or outside near the foundation — and turn that off instead.

After shutting off the water, turn on the faucet handle and let any remaining water drain out. This prevents water from spilling when you open the faucet body. Leave the handle in the on position while you work.

Remove the handle and decorative cap

Most faucet handles have a small decorative cap or plug on top. It is usually plastic or metal and sits flush with the handle. Use a flathead screwdriver or a plastic pry tool to gently pop it off. Do not use a metal screwdriver on a polished finish — wrap it in a cloth first to avoid scratches.

Under the cap is a screw. Remove it with the correct screwdriver — usually a Phillips head, sometimes a hex key. Keep the screw in a small cup so you do not lose it. Pull the handle straight toward you and off the faucet body. If it is stuck, wiggle it gently side to side while pulling.

On some faucets, the decorative cap is not removable. Instead, you will see a set screw on the side of the handle. Loosen that screw and slide the handle off.

Unscrew and remove the old cartridge

Once the handle is off, you will see the faucet body. On most faucets, there is a large nut or collar holding the cartridge in place. Use an adjustable wrench or a cartridge removal tool (a specialized wrench that comes with some cartridges) to unscrew it counterclockwise. Turn it until it comes free in your hand.

Some faucets have a single bolt instead of a collar. Use a hex key or Phillips screwdriver to remove it. Once the fastener is out, grasp the cartridge stem — the part sticking up — and pull it straight up and out of the faucet body. It may take firm pressure. Do not twist it; pull straight up.

Lay the old cartridge on a paper towel. You may see rubber seals and springs inside the cavity where it sat. These are normal. Do not clean them out unless they are visibly clogged with mineral deposits. If they are, rinse them gently with white vinegar on a soft cloth.

Install the new cartridge and reassemble

Before inserting the new cartridge, check that it has an alignment tab — a small notch or key on one side of the stem. Look at the slot inside the faucet body where the cartridge goes. It should have a matching slot or groove. Align the tab with the slot so the cartridge can only go in one way. This prevents you from installing it backwards.

Slide the new cartridge straight down into the faucet body, pushing firmly until it seats fully. You should feel it click or bottom out. Screw the collar or bolt back in by hand first, then tighten it with your wrench. Do not over-tighten; snug is enough. Reattach the handle and screw, then pop the decorative cap back on.

Turn the water back on at the shutoff valves under the sink, or at the main shutoff if that is what you used. Turn on the faucet and check for leaks around the base and under the sink. The handle should move smoothly. If it is stiff or does not control temperature properly, turn off the water, remove the handle, and check that the cartridge is fully seated. If it still does not work, the cartridge may be installed backwards — remove it, rotate it 180 degrees, and reinstall it.

Troubleshooting common problems after replacement

If water still drips from the spout after you install the new cartridge, the cartridge may not be fully seated. Turn off the water, remove the handle, and push the cartridge down harder. You should hear or feel a click. Reassemble and test again.

If the handle is very stiff or will not turn, you may have installed the cartridge backwards. The alignment tab should match the slot in the faucet body. Remove the handle, pull the cartridge out, rotate it 180 degrees, and reinstall it. If stiffness continues, the cartridge may be defective — return it to the store and ask for a replacement.

If water leaks from under the handle where it meets the faucet body, the packing nut (a small nut at the base of the cartridge stem) may be loose. Use a small wrench to tighten it a quarter turn. Do not over-tighten or the handle will become stiff.

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 will not be able to see what you are doing. Always shut off the water supply first, either at the valves under the sink or at the main shutoff. It takes two minutes and prevents a mess.

What if I install the cartridge backwards?

The faucet will not work properly — the handle will be stiff, or hot and cold will be reversed. Remove the handle, pull the cartridge straight up, rotate it 180 degrees, and push it back in. The alignment tab should match the slot in the faucet body.

How do I know which direction to turn the shutoff valves?

Turn them clockwise — the same direction as tightening a screw. You will feel resistance. Stop when the valve stops turning; do not force it. To turn the water back on, turn counterclockwise.

Do I need special tools to replace a cartridge?

You need a screwdriver, an adjustable wrench, and possibly a hex key. Some cartridges come with a specialized removal tool. A plastic pry tool helps remove decorative caps without scratching. You probably have most of these already.

What if the new cartridge leaks when ready?

Check that it is fully seated by pushing it down firmly. If it still leaks, turn off the water and remove it. Look inside the faucet body for debris or mineral buildup. Rinse it with white vinegar and a soft cloth. Reinstall the cartridge and test again. If leaking continues, the cartridge may be defective — return it for a replacement.