How to Fix a Running Bathroom Faucet

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9 min read|Updated: Jun 27, 2026|By Home Repair Expert

Quick Answer

A running bathroom faucet is almost always caused by a worn cartridge, O-ring, or washer inside the valve body. Shut off the water at the shut-off valves under the sink, remove the handle and trim, pull out the cartridge or stem, and replace the worn part. Most repairs cost under $15 in parts and take 15-30 minutes.

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A running bathroom faucet is more than just an annoyance – that constant trickle can waste gallons of water every day and slowly drive up your utility bill. The good news is that most running faucets are caused by a few common, easy-to-fix problems, and you can usually solve them yourself in under an hour with basic tools.

In this guide, we will walk through exactly why your bathroom faucet keeps running and how to fix it step by step, whether you have a compression faucet, a cartridge faucet, or a ceramic disc model.

Why Your Bathroom Faucet Keeps Running

Before you grab your tools, it helps to understand the cause. A faucet that won’t stop running usually points to one of these issues:

• Worn washer or O-ring: In compression faucets, a rubber washer creates the seal. Over time it hardens, cracks, or wears down, letting water seep through.
• Damaged cartridge: Cartridge faucets rely on an internal cartridge to control flow. When it wears out, water keeps moving even when the handle is off.
• Corroded valve seat: Mineral buildup around the valve seat prevents a tight seal.
• Loose or worn parts: Sometimes a simple loose nut or aging internal component is all it takes to cause a constant drip.

Tools and Materials You Will Need

• Adjustable wrench
• Phillips and flathead screwdrivers
• Replacement washers, O-rings, or cartridge (match your faucet model)
• Plumber’s grease
• White vinegar (for cleaning mineral deposits)
• An old towel or rag

Step-by-Step: How to Fix a Running Bathroom Faucet

Step 1: Turn Off the Water Supply

Look under the sink for the shutoff valves and turn them clockwise until the water is off. If there are no local valves, shut off the main water supply to your home. Open the faucet to release any remaining pressure and water in the line.

Step 2: Plug the Drain

Place a rag or drain stopper in the sink so you don’t lose small screws or parts down the drain while you work.

Step 3: Remove the Handle

Pry off the decorative cap on top of the handle to reveal the screw. Unscrew it and gently lift the handle off. If it’s stuck due to corrosion, wiggle it carefully or use a handle puller.

Step 4: Inspect and Replace the Worn Part

Depending on your faucet type, remove the retaining nut and pull out the cartridge, or remove the stem to access the washer and O-ring. Examine each part closely. Replace anything that looks worn, cracked, or corroded with an exact-match replacement. Take the old part to the hardware store if you’re unsure which one to buy.

Step 5: Clean the Valve Seat

While everything is apart, soak any mineral-encrusted parts in white vinegar and wipe down the valve seat. This ensures a clean, tight seal once reassembled.

Step 6: Reassemble and Test

Apply a thin layer of plumber’s grease to the new parts, then reassemble the faucet in reverse order. Turn the water supply back on slowly and test the faucet. The running should stop completely.

When to Call a Plumber

If you’ve replaced the worn parts and the faucet still runs, the valve seat may be too corroded to seal, or there could be a hidden issue in the supply line. In that case, calling a licensed plumber is the safer choice and can prevent further water damage.

Final Thoughts

Fixing a running bathroom faucet is one of the most satisfying and budget-friendly DIY repairs you can do. With a few inexpensive parts and about 30 minutes, you can stop wasting water and save money on every future bill. Keep a small repair kit of washers and O-rings on hand so you’re ready the next time a faucet acts up.