Quick Answer:

If the bathtub faucet won’t shut off, start by making sure the handle is fully in the off position and check the handle adapter or set screw for looseness. Many persistent leaks come from a worn cartridge or valve inside the faucet. If you can’t stop the flow quickly, turn off water to the house and follow temporary steps to protect floors and finish materials.

Why This Happens

Bathtub faucets usually fail to stop completely for a few common reasons:

• Worn cartridge or valve seat: internal seals and cartridges wear out over time and allow water to pass even when the handle is “off.”
• Loose or broken handle adapter/set screw: if the handle isn’t engaging the cartridge properly, the valve may not close fully.
• Debris or corrosion: mineral buildup or corrosion can prevent a tight seal.
• Plumbing pressure or a stuck stem: parts that are seized or bent can leave the valve partly open.

Step-by-Step What to Do

1. Confirm handle position

• Make sure the handle is rotated fully to the off position. If you have separate hot and cold controls, check both.
• With single-lever faucets, move the lever slowly to feel if it reaches an obvious stop. Sometimes the lever sits slightly off center and the valve remains partly open.

2. Inspect the handle adapter and set screw

• Look for a small cap on the handle—pop it off with a flat tool and check the set screw. If the handle is loose, tightening the screw gently may restore proper engagement.
• Do not force the screw; if it’s stripped or corroded, avoid aggressive turning. If tightening the screw fixes the engagement and the faucet stops, you have a quick repair.

3. Identify cartridge symptoms

• Common signs the cartridge or valve is the problem:
  • Water drips or runs constantly even with the handle fully off.
  • Handle is hard to turn, sticks, or wobbles.
  • Visible corrosion or mineral deposits around the spout or handle.
• Cartridge replacement is a common fix. If you are comfortable and have the correct replacement part and the water turned off, you can replace it yourself. If not comfortable, stop and call a plumber.

4. Use the house shutoff if you can’t stop the flow

• If the faucet won’t close and water continues to run, shut off the supply to the fixture or the whole house. Locate your main shutoff valve and turn it off to stop all water flow.
• Turn both hot and cold sides off if you can isolate those valves. If you don’t have local shutoffs, the house main will stop the flow until the faucet is repaired.

5. Temporary steps to stop water safely

• Place a bucket under the spout or catch water in the tub if the flow is slow. Use towels or a waterproof barrier to protect floors and baseboards from splashes or overflow.
• Turn off the water to the house if you cannot stop the fixture. If you need instructions, consult guidance on how to shut off water to your house.
• Open nearby faucets to relieve pressure after turning off the main. This helps reduce dripping while you arrange repairs.
• Dry and ventilate the area as soon as flow is controlled to reduce risk of water damage and mold.

What Not to Do

• Do not force the stem or handle—forcing can break internal parts and make the repair more expensive.
• Do not keep tightening random screws hoping to stop the leak—overtightening can strip screws or damage components.
• Do not leave the tub running unattended while you try fixes—continuous flow can cause overflow and serious water damage.

When to Call a Professional

• Call a plumber if you cannot stop the water with the house shutoff, the cartridge appears broken or stuck, or you see water seeping into walls or floors.
• Also call a pro if you’re unsure which replacement part you need or if corrosion and mineral buildup are extensive—those situations benefit from proper diagnosis and part matching.
• If you detect water damage already happening (soft floors, bulging walls, persistent dampness), get a plumber quickly to prevent bigger repairs.

Safety Notes

• Always shut off water before you disassemble faucets. If you can’t isolate the fixture, use the house main to stop the flow.
• Watch for slip hazards from water on floors and use towels or a mop to keep the area safe.
• Electrical items near the tub should be moved away from water and outlets should remain dry. If water reaches electrical outlets, shut off power to that area and call an electrician.

Common Homeowner Questions

• Why does my faucet drip even when the handle is off?
  A worn cartridge, damaged seat, or failed seal usually lets small amounts of water pass even when off.
• Can I replace the cartridge myself?
  Yes, if you feel comfortable and have the right replacement part and the water is shut off; otherwise hire a plumber.
• How fast do I need to act?
  Act immediately to stop flow to avoid water damage; use the house shutoff and protective measures while arranging a repair.