How to Fix Leaky Sink Faucet Bathroom: A Step-by-Step Guide

Updated November 2026

Learning how to fix leaky sink faucet bathroom problems usually comes down to three things: shutting off the water, identifying the faucet type, and replacing the worn part causing the drip. Most leaks come from a worn washer, O-ring, cartridge or valve seat, and each of these is inexpensive and manageable with basic hand tools. This guide walks you through the process from start to finish.

Identify the Faucet Type and Source of the Leak

Before you take anything apart, figure out what kind of faucet you have, because the repair depends on it. Single-handle faucets usually use a cartridge or ball mechanism, while two-handle faucets typically use compression stems with rubber washers. Check whether the drip comes from the spout, which usually points to a worn cartridge, washer or O-ring, or from the base of the handle, which often points to a loose packing nut or worn O-ring.

Shopping for one? See our guide: Bathroom Sink Faucet Drip Repair: 5 Best Kits for Every Fix (2026).

If you are unsure which mechanism you have, look for a brand name or model number on the faucet body or under the sink. Manufacturers such as Moen and Delta publish repair guides for their specific models, and many of those guides include exploded diagrams of the internal parts.

Shut Off the Water and Prepare the Work Area

1. Locate the two shutoff valves under the vanity and turn them clockwise until they stop. If the valves are stiff or do not close fully, shut off the main water supply to the house instead.
2. Open the faucet to relieve remaining pressure and let any water drain out.
3. Place a towel in the sink basin and cover the drain. Small parts like screws and washers can fall in and disappear quickly.
4. Set a small tray or bowl nearby to hold parts in the order you remove them.

Replace the Worn Cartridge, Washer or O-Ring

Once the water is off, remove the handle by loosening the set screw, usually hidden under a decorative cap. Then remove the cartridge or stem using the correct tool for your model. Compare the old part to its replacement before installing it, and take the old part to the hardware store if you need an exact match.

Working With Compression Faucets

On a compression faucet, unscrew the stem, remove the old rubber washer, and seat a new washer of the same size. Apply a light coat of plumber’s grease to the threads and the new washer. Tighten the stem by hand first, then snug it with a wrench. Overtightening can damage the seat and create a new leak.

Working With Cartridge Faucets

For a cartridge faucet, pull out the old cartridge and note how it sits, especially the orientation of its notches and the position of the hot and cold markings. Insert the new cartridge in the same orientation, reinstall the retaining clip or nut, and reattach the handle. Turn the water on slowly and test the faucet.

Test the Faucet and Check for Remaining Leaks

Turn the shutoff valves back on slowly to avoid a sudden surge that could loosen fittings. Run the faucet at low and high settings, then turn it off completely and watch the spout for several minutes. If the drip continues, the seat may be worn or scratched, and you may need a seat wrench or a replacement faucet body.

Recommended Gear

• Plumber’s grease helps lubricate O-rings and washers so they seal properly and stay in place. View on Amazon
• Adjustable wrench gives you grip on packing nuts and stems without marring the finish. View on Amazon
• Faucet repair kit bundles common washers, O-rings and cartridges for many models in one package. View on Amazon

Common Mistakes and Tips

• Skipping the shutoff check. Confirm the water is off by opening the faucet before you start.
• Forcing parts that do not match. A part that almost fits is usually the wrong size or style.
• Overtightening handles and stems, which can crack housings or deform seats.
• Installing a cartridge backward, which often causes hot and cold to reverse.
• Ignoring a worn valve seat. If the drip returns after a new washer or cartridge, the seat is the likely cause.

For more model-specific help, see Bathroom Faucet Repair Kits: How to Fix a Leaky Faucet in 6 Steps and Bathroom Tub Faucet Dripping: How to Find and Fix the Leak. If you are working on a Moen fixture, Fix Moen Bathroom Faucet: A Practical Guide (2026) covers cartridge-specific steps.

FAQ

How do I know which part is leaking?

A drip from the spout usually means a worn cartridge, washer or O-ring, while water leaking at the base of the handle often points to a loose packing nut or worn O-ring. Identifying the faucet type first will tell you which part to check.

Do I need to replace the whole faucet?

In most cases, no. Replacing the cartridge, washer or O-ring fixes the majority of bathroom faucet leaks. A full replacement is more likely needed if the valve seat is badly corroded or the faucet body is cracked.

When should I call a plumber?

If the water shutoff valves will not close, or if the leak involves pipes inside the wall or floor, contact a licensed plumber. Water damage can be costly, so consult a professional when you are unsure.

Conclusion

Fixing a leaky bathroom faucet is usually a matter of shutting off the water, identifying the faucet type, and replacing the worn cartridge, washer or O-ring. Take photos or notes as you disassemble, and work slowly to keep small parts organized. With the right part and a careful reassembly, most drips stop for good.

Related reading

• How to Fix a Dripping Bathroom Faucet: A Step-by-Step Guide for Beginners
• Bathroom Faucet Is Leaking: How to Find and Fix the Drip Yourself

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