What a tub faucet stem is and why it fails
The stem is the part inside your faucet handle that turns to open and close the water. It sits inside the faucet body and connects to a washer or cartridge that actually stops the flow. When a stem wears out, you get a drip that won't stop, water that leaks from under the handle, or a handle that spins without turning the water on or off.
Stems fail because the rubber washers inside them compress and crack after years of use, or because mineral buildup from hard water locks them in place. Replacing the stem is cheaper than replacing the whole faucet and takes about an hour if you have the right tools and the right replacement part.
The hardest part is finding the correct stem for your faucet. Faucet stems are not universal — a stem for a Moen faucet will not fit a Delta or Kohler. You need to know your faucet brand and often the model number before you buy.
Key Takeaways
- Faucet stems are brand-specific, so you must identify your faucet brand and model before buying a replacement.
- The basic steps are: turn off the water, remove the handle, unscrew the packing nut, pull out the old stem, and screw in the new one.
- You will need an adjustable wrench, a screwdriver, and possibly a stem removal tool, depending on your faucet type.
- Mineral buildup can lock a stem in place; soaking it in vinegar or using penetrating oil can help free it.
Identify your faucet brand and find the right stem
Look at the faucet itself for a brand name stamped or printed on the body. Common brands are Moen, Delta, Kohler, Pfister, and Grohe. If you cannot see a name, check under the sink for the original paperwork or look at the shut-off valves — sometimes the brand is marked there.
Once you know the brand, look for a model number. On some faucets it is printed on the body. On others you may need to remove the handle to see it stamped on the faucet body itself. Write down both the brand and model number.
Take this information to a plumbing supply store or search online for "[brand] [model] faucet stem." Stems cost between $15 and $40 depending on the brand. Buying the wrong stem means a wasted trip back to the store, so verify the part number matches your faucet before you leave the counter or check out online.
Turn off the water and remove the handle
Locate the shut-off valves under the sink — one for hot water and one for cold. Turn both clockwise until they stop. If you cannot find shut-off valves under the sink, you will need to shut off the main water supply to the house. Turn on the faucet to confirm the water is off.
Look at the handle. Most handles have a small cap or button on top or behind the handle. Pry this off with a flat screwdriver — it usually covers a screw. Remove the screw and pull the handle straight toward you. Some handles are held by a set screw on the side instead; loosen that screw and the handle will slide off.
Once the handle is off, you will see the packing nut — a hexagonal nut that sits just below where the handle was. This nut holds the stem in place.
Remove the packing nut and extract the old stem
Use an adjustable wrench to turn the packing nut counterclockwise. Turn it by hand once it is loose enough — do not force it. Remove the nut completely and set it aside.
Now you can see the stem itself. On some faucets you can straightforward pull it straight out. On others, especially older Delta faucets, the stem has a slot on the end that requires a special stem removal tool — a long handle with a fork or hook on the end. If your stem has a slot, you will need this tool; a plumbing supply store can sell you one for $5 to $10, or you can rent one.
If the stem is stuck, do not force it. Spray penetrating oil like WD-40 around the stem where it enters the faucet body. Let it soak for 15 to 30 minutes. You can also soak a cloth in white vinegar and wrap it around the stem to dissolve mineral buildup. Try again gently after soaking.
Install the new stem and reassemble
Before you insert the new stem, check that it matches the old one in length and thread direction. The threads should spiral the same way. Insert the new stem straight into the faucet body, pushing it in until it stops. Do not force it — it should slide in smoothly.
Screw the packing nut back on by hand first, then tighten it with the wrench. Tighten it firmly but not so hard that you strip the threads — you should feel resistance but still be able to turn it with moderate pressure.
Slide the handle back onto the stem and insert the screw. Tighten the screw and snap the cap back on. Turn the shut-off valves back on by turning them counterclockwise. Turn on the faucet and check for leaks around the handle and at the base of the faucet.
Adjust the handle position and test for leaks
Once the water is back on, the handle may point in a different direction than it did before. This is normal. You can adjust it by loosening the handle screw slightly, rotating the handle to the position you want, and tightening the screw again.
Let the faucet run for a minute and watch for drips from under the handle or from the base where the faucet meets the sink. A small amount of water under the handle is normal for the first few minutes as air works out of the line. If water continues to drip after five minutes, the packing nut may need to be tightened another quarter turn.
Test the handle movement. It should turn smoothly without grinding or catching. If it feels rough, the stem may not be fully seated. Turn off the water, remove the handle, and push the stem in a bit further, then reassemble.
What to do if the stem is stuck or the faucet leaks after replacement
A stuck stem usually means mineral buildup has hardened around it. Soak it with penetrating oil for several hours or overnight, then try again. If it still will not budge, you may need to soak the entire faucet body by plugging the drain and filling the sink with a vinegar-and-water solution for a few hours.
If the faucet leaks from under the handle after you install the new stem, the packing nut is too loose. Tighten it another quarter turn with the wrench. If it leaks from the spout itself, the new stem may not be the correct part — compare the part number on the box to the number you wrote down from your faucet.
If you cannot stop a leak and you have confirmed the stem is the right part, the faucet body itself may be damaged. At that point, replacing the entire faucet is usually cheaper than trying to repair it further.
Frequently Asked Questions
Do I need to turn off the water at the main if I cannot find shut-off valves under the sink?
Yes. If there are no shut-off valves under the sink, locate your main water shut-off valve — usually in the basement, crawl space, or outside near the foundation. Turn it clockwise until it stops. This cuts water to the entire house, so tell anyone else in the house before you do this.
Can I replace just the washer instead of the whole stem?
On older faucets with a straightforward stem design, yes — you can remove the stem, unscrew the packing nut at the bottom, and replace the rubber washer inside. On newer cartridge-style stems, the washer is not replaceable; you must replace the entire stem.
What if the handle turns but no water comes out?
This usually means debris is blocking the aerator — the screen at the tip of the spout. Unscrew the aerator by hand or with a wrench, rinse it under running water, and screw it back on. If water still does not flow, the new stem may be installed backward or the shut-off valves under the sink may not be fully open.
How long does a new stem last?
A quality replacement stem typically lasts 10 to 15 years, depending on water hardness and how often the faucet is used. Hard water shortens the lifespan because mineral buildup wears the internal parts faster.
Can I replace a stem on a faucet with a single handle?
Yes, but the process is slightly different. Single-handle faucets usually have a cartridge instead of a traditional stem. The cartridge pulls straight out after you remove the handle and a retaining clip. Bring the old cartridge to the store to match the replacement, as cartridges vary by brand.