What a faucet stem is and why it fails

The stem is the part inside your faucet that moves when you turn the handle. It's a shaft with threads on one end that screws into the faucet body, and a tapered cone at the other end that opens and closes the water valve. When you turn the handle, you're rotating the stem, which lifts that cone and lets water through.

Stems wear out because water and minerals pass over them constantly. The rubber seal at the base of the stem hardens and cracks, usually after five to fifteen years depending on your water quality and how often you use the tub. When the seal fails, water leaks from under the handle or drips from the spout even when the handle is fully closed. Replacing the stem is the standard fix—it's cheaper and faster than replacing the whole faucet.

Key Takeaways

  • Turn off the water supply to the tub before you start, using the shutoff valve under the sink or in the wall behind the tub.
  • You need to know whether your faucet is a compression faucet (two handles) or a cartridge faucet (one handle), because the stem design is different for each.
  • Buy a replacement stem that matches your faucet brand and model—stems are not universal, so bring the old one to the hardware store or look up your faucet's model number online.
  • The job takes thirty minutes to an hour and requires only basic tools: a screwdriver, adjustable wrench, and possibly a stem removal tool if the stem is stuck.

Shut off the water before you touch anything

Locate the shutoff valve under the sink. It's usually a small oval knob on the pipe coming from the wall. Turn it clockwise until it stops—you should feel resistance, not a hard stop. If there's no valve under the sink, look in the wall behind the tub or in the basement directly below it. Some older homes have a main shutoff only; if that's your situation, turn it off at the meter or where the water line enters the house.

Turn on the tub faucet and let it run for a few seconds to confirm the water is off. If water still comes out, the valve didn't close all the way—turn it a bit more. If water still flows, the valve itself is broken and you'll need to call a plumber to replace it before you can safely work on the faucet stem.

Remove the handle and expose the stem

Look at the handle. Most handles have a small cap or button on top or on the side—this is usually a decorative cover hiding a screw. Pry it off gently with a flat screwdriver. If there's no cap, the screw may be hidden under a label or sticker. Once you find and remove the screw, the handle should pull straight off.

Under the handle, you'll see a packing nut—a hexagonal nut that holds the stem in place. This is what you need to unscrew next. Use an adjustable wrench to turn it counterclockwise. It usually takes three to five full turns before it comes loose. Once it's loose enough, you can often unscrew it by hand. Set it aside in a safe place.

Identify your faucet type and remove the stem

Look at what's now exposed in the faucet body. If you see a single shaft with a flat or notched top, you have a compression faucet—the most common type in older homes. If you see a cartridge (a plastic or metal cylinder about two inches long), you have a cartridge faucet, and you'll need a different replacement part. The instructions below cover compression stems, which are the most straightforward to replace.

For a compression stem: grip the stem with an adjustable wrench just below the packing nut and turn it counterclockwise. It should unscrew like a bolt. If it's stuck, explore penetrating oil (like WD-40) and wait fifteen minutes, then try again. Do not force it—if you strip the threads, you'll need a plumber. Once it's loose, unscrew it by hand and pull it straight out.

Buy the correct replacement stem

Take the old stem to a hardware store or home improvement center. Show it to the staff and tell them your faucet brand if you know it. Stems are brand-specific—a Moen stem won't fit a Delta faucet. If you can't bring the stem, look for the faucet brand name on the faucet body itself (usually stamped or printed near the base), then search online for "[brand name] faucet stem" along with your faucet model number if you can find it. Many manufacturers print the model on a label under the sink.

Replacement stems cost between eight and twenty dollars. Buy a stem kit if available—it usually includes the stem, a new rubber seal, and a washer, which is cheaper than buying them separately and ensures all the parts match.

Install the new stem and reassemble

Before you screw in the new stem, wrap the threads with plumber's tape (also called PTFE tape or Teflon tape). Wrap it clockwise around the threads three to four times—this creates a watertight seal and makes the stem easier to remove next time. Screw the new stem into the faucet body by hand first, then use the wrench to tighten it. It should be snug but not forced—you're aiming for firm resistance, not maximum tightness.

Screw the packing nut back on by hand, then tighten it with the wrench. It should be tight enough that you can't turn it by hand, but not so tight that you need all your strength. Screw the handle back on, then replace the cap or button. Turn the water back on at the shutoff valve and test the faucet. It should turn smoothly and not drip when fully closed.

What to do if the stem won't come out or the leak continues

If the stem is stuck and won't budge after explore penetrating oil, stop trying. Forcing it risks breaking the faucet body, which means replacing the entire faucet. Call a plumber at this point—they have specialized tools and experience removing seized stems without damage.

If you've installed the new stem and water still drips from the spout, the most common cause is that the packing nut is too loose. Tighten it another quarter turn with the wrench. If it still drips after that, the new stem may be the wrong model for your faucet—take it back to the store and confirm the brand and model with the staff. If water leaks from under the handle instead of the spout, the packing nut is too tight; loosen it slightly until the leak stops.

Frequently Asked Questions

Can I replace just the rubber seal instead of the whole stem?

Yes, if the stem itself isn't corroded or damaged. The seal is usually held on with a small screw or clip at the bottom of the stem. However, if the stem is discolored, pitted, or rough to the touch, replacing the whole stem is safer and costs only a few dollars more. A damaged stem will wear out a new seal quickly.

What if my faucet has one handle instead of two?

That's a cartridge faucet, not a compression faucet. The replacement part is different—it's called a cartridge, not a stem. The removal process is also different and usually requires a cartridge puller tool. Look up your faucet brand and model online to find the correct cartridge, or bring a photo of the faucet to the hardware store and ask for help identifying it.

Do I need to turn off the water if I'm just replacing the stem?

Yes, always. Even though the valve should close when you turn the handle, water sits in the pipes behind the faucet. When you unscrew the stem, that water will leak out. Turning off the shutoff valve prevents water from flowing and makes the job much cleaner and faster.

How long does a new stem last?

A replacement stem typically lasts as long as the original one did—five to fifteen years depending on water quality and use. Hard water and frequent use shorten the lifespan. If you notice the faucet starting to drip again after several years, the new stem's seal has worn out and it's time to replace it again.