How to Fix a Leaky Kitchen Faucet: Find the Leak, Replace the Part, Know When to Stop

Most leaky kitchen faucets can be fixed in under an hour by shutting off the water, finding where the leak starts, and replacing one cheap part: a cartridge, a washer, an O-ring or a seal. The trick is matching the repair to the type of leak, because a drip from the spout, a puddle at the base and a spray from the handle all come from different places. This guide, based on published specifications, manufacturer documentation and general plumbing knowledge, walks through the full process, from identifying the faucet to testing the repair. It also explains what can go wrong and when it is smarter to stop and call a plumber.

Find where the water is coming from

Before touching a tool, watch the faucet and dry it with a towel so new water stands out. Run it, shut it off, and note where droplets appear. The location tells you which part has failed.

• Dripping from the spout tip: the valve is not sealing. Think cartridge, ceramic disc or washer and seat.
• Leaking around the base of the spout: worn O-rings on a swivel spout or a loose mounting.
• Leaking around the handle: a worn packing, O-ring or loose retaining part under the handle.
• Water under the sink only: supply lines, connections, the hose or the shutoff valves, not necessarily the faucet itself.
• Spray head or hose leak: a worn washer in the sprayer or a damaged hose.

Open the cabinet and look with a flashlight while someone runs the water. A dry paper towel pressed against each connection quickly shows which one is damp.

Prerequisites: tools, parts and safety

Gather everything before you begin so the faucet is not left in pieces overnight. A typical kit includes an adjustable wrench, a screwdriver set, a hex key set, pliers, plumber’s grease, a small container for screws, a flashlight and a towel. Penetrating oil can help with stuck parts. You may also need white vinegar to clean mineral deposits and a replacement part matched to your model.

For safety, close the shutoff valves under the sink, usually by turning them clockwise until snug, and then open the faucet to drain pressure. If the valves are missing or will not close, shut off the main supply to the house. Put the stopper in the sink drain so small screws cannot fall in, and lay a towel in the basin to protect the finish. Take photos at every stage, because reassembly is much easier when you can see the original order.

Identify the faucet type

The repair depends on how the faucet works inside. A two-handle faucet is often a compression type with rubber washers, or a ceramic disc type that opens with a quarter turn. A single-handle faucet usually contains a cartridge, a ball valve or a ceramic disc cartridge. Pull-down and pull-out models add a hose and sometimes a diverter on top of the same valve design.

Look for the brand name on the body or the handle, and search the manufacturer’s website with the model number. Most makers publish exploded diagrams that show every part and its name. That diagram is the most reliable way to order the correct replacement, since many cartridges look alike but differ in size, length and splines.

Step by step: replace a worn cartridge or washer

These steps apply to a typical single-handle cartridge faucet. Compression faucets follow the same logic with a stem and washer instead. Always follow your manufacturer’s instructions, which may differ.

1. Shut off both shutoff valves, open the faucet, and confirm the water has stopped flowing.
2. Pry off the decorative cap on the handle or look for a set screw, then loosen it with the correct hex key or screwdriver and lift off the handle.
3. Remove the retaining nut, clip or cap that holds the cartridge, using pliers or a wrench wrapped in a cloth to avoid scratching.
4. Note the position of the cartridge, then pull it straight out. If it is stuck, wiggle it gently and use penetrating oil rather than force.
5. Inspect the cavity. Clean mineral deposits from the seat with white vinegar and a soft brush, and check for scoring or cracks.
6. Coat new O-rings lightly with plumber’s grease, insert the new cartridge in the same orientation, and secure the retaining parts.
7. Reattach the handle, open the shutoff valves slowly, and run the faucet for a minute while checking for leaks.

For a compression faucet, unscrew the stem, replace the rubber washer and the small screw that holds it, and consider replacing the O-ring at the same time. If the seat inside the body is rough, a seat wrench or reseating tool may be needed.

Fixing leaks at the base, handle or sprayer

Not every leak is a cartridge problem. A leak at the base of a swivel spout generally means worn O-rings. Remove the spout according to the manual, slide off the old rings, clean the grooves, lubricate the new rings and reassemble. A leak under the handle is commonly a worn seal or loose retaining nut, which a small adjustment or replacement can cure.

If the spray head drips, unscrew the head and check the washer or filter inside. A cracked hose or loose hose connection under the sink needs retightening or replacement. Tighten connections by hand first and then a small additional turn with a wrench. Overtightening can crush washers and cause new leaks, which is a very common mistake.

What can go wrong

A few predictable problems turn a quick fix into a longer one. Parts that do not match are the biggest, so confirm the model before buying. Corroded or stuck parts can break if forced, so patience and penetrating oil matter more than strength. A damaged valve seat can leave the faucet dripping even with a new cartridge. Cross-threaded nuts and pinched O-rings cause leaks right after reassembly.

Another trap is debris. When the water returns, loose scale or grit can lodge in the new cartridge, causing weak flow or another drip. Remove the aerator and run the water for a moment to flush the lines before reinstalling it. If something still leaks, shut the water off again and recheck each seal instead of tightening everything harder.

Test the repair and keep it from returning

Open the shutoff valves slowly, run hot and cold separately, and look at every joint. Wipe each area dry and check again after ten minutes, then once more the next morning. Look under the sink for fresh droplets.

To reduce repeat problems, clean the aerator every few months, especially with hard water. Wipe the faucet with mild soap and a soft cloth, and avoid forcing the handle past its stops. If you are not sure how old the faucet is or how much life it has left, our companion guide on how long kitchen faucets last explains the typical ranges and when replacement becomes the better value.

When to stop and call a plumber

Stop if the shutoff valves will not close or leak when turned, if the body is cracked, or if you see corrosion on the pipes themselves. Call a professional if the leak continues after you replace the obvious parts, if you are unsure how to reassemble the faucet, or if water has already soaked the cabinet or floor. A plumber can also check the supply lines and valves, and advise when a new faucet is the sensible choice. For anything involving the main supply or hidden pipes, do not guess.

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Frequently asked questions

Why is a kitchen faucet dripping from the spout?

A drip from the spout when the handle is off usually points to a worn internal part: a cartridge or ceramic disc in most modern faucets, or a rubber washer and seat in older compression models. Mineral scale can also stop a valve from sealing fully. Replacing the cartridge or washer, and cleaning the seat, commonly fixes it. Check your manual for the correct replacement part.

How can you tell which cartridge to buy?

Start with the faucet brand and model number, which may be in the manual, stamped on the body, or on a label under the sink. If you cannot find it, remove the old cartridge and compare it with parts diagrams from the manufacturer, or take it to a plumbing supplier. Buying by appearance alone is risky, because cartridges that look alike can differ in size and splines.

Can a leaky faucet be fixed without turning off the water?

No, it is not advisable. Even a small repair opens internal passages, and water can spray out as soon as the cartridge or handle is removed. Close the shutoff valves under the sink, or the main valve if they do not work, then open the faucet to release pressure. This is the single most important safety step in the whole job.

Why does a faucet still leak after the cartridge is replaced?

Common causes include a damaged valve seat, a cartridge that is not fully seated or aligned, a missing or twisted O-ring, or debris trapped during reassembly. Mineral buildup on the seat can also prevent a seal. Disassemble again, flush and clean the area, check each seal, and reassemble carefully. If the body is cracked or corroded, replacement is usually the answer.

When should a leaky faucet be replaced rather than repaired?

Replacement is worth considering when the body is cracked or heavily corroded, parts are no longer available, the finish is peeling, or repeated repairs have not lasted. If the faucet is old and has several issues at once, a new one may cost about the same as chasing each fault. Compare part costs with a comparable new model before deciding.