How to Replace a Cartridge in a Faucet

Make sure there’s no water flowing before replacing a sink’s faucet cartridge. Follow these steps to shut off the water supply to your sink:

• Use the shut-off valve underneath the sink to cut off the water supply. Be sure the valve closes completely.
• Turn the hot and cold taps on all the way. This lets the water that's still in the pipes run out into the sink. It’ll slow to a trickle and then stop.
• Turn off the taps.
• Plug the drain. Use the stopper handle on the faucet or a traditional stopper. Even a rag will do in a pinch. This is to keep faucet parts or tools from falling down the drain.

When you’re learning how to replace a cartridge faucet, start with the handles.

Faucet hardware with crystal ball decor on the taps usually has decorative covers. Not all faucets have these. If you can see a screw on the handle, skip this step. If you can’t see a screw at the top of the tap handle, you’ll need to remove a cover. 

Use a flat head screwdriver to pop off the plastic cap from the top of each handle. This will expose the screws.

Once you can see the screw on the tap handle, unscrew it. Choose your faucet setup for instructions.

For two handles with screws on top:

• Use a screwdriver to remove each screw. Turn counterclockwise until you can pull the screw out.
• Set the screw aside. Make sure it won’t fall into the drain.
• Carefully pull straight up on the handle. It should come off easily.
• Repeat for the other handle.

For two-angled handles:

• If your faucet has angled handles, the screw may be in a different spot.
• For a screw on the side of a handle, use a hex key or 1/8-inch Allen wrench to loosen it.
• Pull off the handle.
• Repeat for the other angled handle.

For some two-handled faucets:

• You’ll likely need to remove a bonnet nut or retaining nut.
• Unscrew the nut with an adjustable wrench.
• The plastic cylinder with a stem on top is the faucet cartridge. It comes in white, blue or black plastic.

For a cartridge faucet with one handle:

• The screw is on the front of the handle. It might be covered with a nameplate or decoration.
• Use an Allen wrench or hex key to unscrew it.
• Remove the handle.
• The bonnet nut is shaped like a bonnet or dome. Twist it off.
• Put it aside, all in one place.
• You may be able to see the cartridge now.

The cartridge is a plastic cylinder with notches in the side. It has a stem on the top. You’ll see it when you’ve removed enough pieces from the faucet. Part of learning how to remove a faucet cartridge is reaching it.

• Lift out the cartridge and set it aside. Use pliers to grip the stem if you need. If you don’t see the cartridge yet, keep going. For one-handled faucets and some two-handled ones, you may have more pieces to remove. See the next step to learn how to remove a retaining nut and a retaining clip.
• If it’s difficult to remove the cartridge, you may need a special tool. Check the manufacturer’s instructions for your faucet for details.

Tip: If there’s a brass nut on the top of the cartridge, remove it and set it aside. Your replacement might not come with one. You’ll need it to reassemble your faucet properly.

If the cartridge won't budge, check the bottom of the fitting. You may have a retaining nut at the base of the handle. It holds the cartridge in place. Not all faucets have one, but it’s more common on single-handle faucets. If you have a retaining nut, you’ll need to remove it. (If you don’t have one, skip to Step 7).

• Remove the plastic retaining nut. Use water pump pliers, adjustable pliers or a pipe wrench.
• Once you’ve removed the nut, lift the cartridge straight up.
• If you still can’t remove the cartridge, your faucet likely has a retaining clip. The clip is a narrow piece of brass, shaped like a horseshoe. Using needle nose pliers, pull it straight out.

After the cartridge is out, look inside the faucet. Some faucets have an O-ring. It looks like a round rubber O or washer. You may just see a spring. Take out both pieces: 

• If there is an O-ring, remove it. You can hook it on the end of a screwdriver.
• If you can’t slip off the O-ring, cut it with a utility knife.
• Remove a spring if you see one.
• Clean any debris from the faucet housing with a soft cloth.
• Using a rag, soak up any excess water in the faucet handles.

Cartridges come in many shapes and sizes. Rather than trying to figure out how to tell if a faucet cartridge is bad, simply replace it. If you're wondering about it, swap it out. The easiest way to find the correct part is to be prepared:

• Take the O-ring, spring and cartridge to the store with you. That way, you’re sure to find a replacement part that fits. The new faucet parts must be the same size as the old ones.
• Note the faucet’s manufacturer and model number.

Once you have the replacement cartridge, it’s time to fit it into the faucet. Simply reverse the process for taking the faucet apart in Steps 1 through 8:

• Replace any springs in the bottom of the faucet.
• Coat the new O-ring with silicone grease and install on the faucet cylinder.
• Re-attach any retaining clips. Screw on the plastic retaining nut.
• Put a thin slick of plumber’s grease around the part of the cartridge getting inserted.
• For one-handled faucets, match the cold and hot water sides on the cartridge.
• Drop the cartridge into place. Make sure it’s aligned correctly with any notches.
• Screw the bonnet nut back into place.
• Put the handle or handles back on the faucet.
• Screw them in place using a screwdriver or Allen wrench.
• Place the decorative covers back on the handles if needed.

Open the water valve below the sink. Slowly turn on one tap at a time to make sure everything is operating properly.

Tip: Sometimes a one-handled faucet will have hot water coming out of the cold tap. If so, it’s an easy fix. Go back into the faucet and rotate your cartridge half a turn. Once you flip it around, your taps will work as normal.