How to Fix a Sink That Won't Stop Running Water

Understanding Why Your Sink Won’t Stop Running

A continuously running sink is more than just an annoyance — it wastes water, drives up your utility bills, and can signal a failing internal component that may lead to bigger problems if left unchecked. The root cause usually falls into one of a few categories: a worn-out washer, a damaged O-ring, a faulty cartridge, debris lodged in the valve, or even a high-pressure issue in your home’s water supply. Understanding which type of faucet you have and what’s failing inside will save you time, money, and unnecessary frustration.

The most common offender is a rubber washer or seal that has hardened, cracked, or disintegrated over time. In cartridge-style faucets, the plastic or ceramic cartridge itself can wear out or become clogged with sediment. Less frequently, the issue may stem from a loose or corroded valve seat or a problem with the shut-off valve under the sink. By methodically inspecting each component, you can usually pinpoint the problem within minutes.

Keep in mind that the repair approach differs depending on whether you have a compression faucet, a cartridge faucet, a ball-type faucet, or a ceramic-disc faucet. Each design uses a different mechanism to control water flow, so identifying yours is the first real step toward a lasting fix.

Tools and Materials You’ll Need

Before you begin, gather the following items. Having everything within reach will prevent unnecessary trips to the hardware store and help you complete the job in one sitting.

Screwdriver set – both flat-head and Phillips, in various sizes to accommodate different screws and retaining clips.
Adjustable wrench – for loosening nuts and fittings. A basin wrench is helpful if you have limited space under the sink.
Allen wrench set – many modern faucets use hex screws to secure the handle.
Replacement parts – washers, O-rings, cartridges, or valve seats specific to your faucet brand and model. Check your owner’s manual or take the old part to the store for a match.
Plumber’s tape (PTFE tape) – for sealing threaded connections and preventing leaks.
Plumber’s grease – a silicone-based lubricant that helps O-rings and seals slide into place and last longer.
Cloth or rag – to catch drips, protect the countertop, and clean up any spills.
Penetrating oil – useful if any nuts or screws are corroded or stuck.
Flashlight or work light – for seeing into dark spaces under the sink and inside the faucet body.
Small bucket or bowl – to catch water that drips out when you disconnect lines.

Safety First: Turn Off the Water Supply

Before touching any part of the faucet, locate the shut-off valves underneath the sink. These are typically small, oval or round valves — one for hot water and one for cold water — mounted on the pipes leading up to the faucet. Turn both valves clockwise (to the right) until they stop. If you cannot turn them by hand, use an adjustable wrench gently to avoid damaging the valve.

Once the valves are closed, open the faucet handle to release any pressure and drain the remaining water from the lines. This will prevent a mess when you disassemble the faucet. If no water comes out when you open the handle, you’ve successfully isolated the supply.

Important: If your sink does not have individual shut-off valves under the sink, you will need to shut off the main water supply to your home. This is usually located near the water meter or where the main line enters the house. Turning off the main supply is a last resort, but it is necessary for safety. Learn how to find your home’s main water shut-off valve here.

Diagnosing the Problem: Identify Your Faucet Type and Likely Failure

Not all faucets are built the same. The repair method that works on a compression faucet will not necessarily fix a cartridge faucet. Take a moment to identify what kind of faucet you have before you start disassembling anything.

Compression Faucets

These are the old-style two-handle faucets (one for hot, one for cold). They use a rubber washer that presses down against a valve seat to stop water flow. When that washer wears out, the faucet drips or runs continuously. Compression faucets are common in older homes, and they are relatively straightforward to rebuild.

Cartridge Faucets

These can be either single-handle or two-handle designs. Inside, a plastic or brass cartridge moves up and down (or side to side) to control flow and temperature. If the cartridge cracks, gets clogged with sediment, or loses its seal, water will run continuously. Cartridge faucets are very common in modern kitchens and bathrooms.

Ball-Type Faucets

Typically found in single-handle kitchen faucets, ball-type faucets use a rotating ball with slots and springs to regulate water flow and temperature. The ball can wear out, or the springs and seals beneath it can fail. These are somewhat less common today but still appear in many homes.

Ceramic-Disc Faucets

These use two ceramic discs that slide against each other to open or close the water flow. They are very durable and long-lasting, but if a disc cracks or if debris gets trapped between the discs, the faucet may not shut off completely. Ceramic-disc faucets are the most reliable type when maintained properly.

Once you know your faucet type, you can move forward with the repair steps that apply to your specific model. If you are unsure, take a photo of your faucet and visit your local hardware store or use this guide from Home Depot to identify your faucet type.

Step-by-Step Repair Process by Faucet Type

Below are detailed repair procedures for each of the four main faucet types. Follow the section that matches your setup. Always work on a clean, well-lit surface, and keep track of every screw and small part as you remove them.

Repairing a Compression Faucet (Two-Handle)

Compression faucets are the easiest to diagnose and rebuild. If water runs continuously from a two-handle faucet, one or both of the stem washers has likely failed.

Remove the handle. Look for a small screw on the side or under a decorative cap on top of the handle. Use a flat-head screwdriver to pry off the cap, then remove the screw and lift off the handle.
Unscrew the packing nut. Use an adjustable wrench to loosen and remove the packing nut that holds the valve stem in place. You may see a metal or plastic retaining ring underneath — remove that as well.
Pull out the valve stem assembly. Grasp the stem and pull it straight out. You’ll see a rubber washer at the bottom of the stem, held on by a small brass screw.
Remove the old washer. Unscrew the brass screw, remove the worn washer, and clean any debris from the stem body. Apply a thin layer of plumber’s grease to the new washer and install it with the brass screw. Tighten the screw, but do not overtighten — you can strip the threads.
Inspect the valve seat. Look at the brass seat inside the faucet body where the washer makes contact. If it is rough, pitted, or corroded, use a valve seat wrench or a seat-dressing tool to smooth it. A damaged seat will ruin a new washer quickly.
Reassemble in reverse order. Slide the stem back in, tighten the packing nut, reattach the handle, and secure the screw. Replace the decorative cap if there is one.
Test the repair. Turn the water supply back on and operate the handle. If the water stops completely and there are no leaks, the repair is successful.

Repairing a Cartridge Faucet (Single-Handle or Two-Handle)

Cartridge faucets are very common. The cartridge itself is a sealed unit, so the fix is usually a straight replacement. Here’s how to do it.

Remove the handle. For a single-handle faucet, look for a set screw on the side of the handle (often covered by a small plastic plug). Loosen the set screw with an Allen wrench and lift the handle off. For a two-handle cartridge faucet, remove the screw under the cap and pull off the handle.
Remove the retaining clip or nut. Many cartridge faucets have a metal or plastic retaining clip that holds the cartridge in place. Pull the clip out with pliers, or use a wrench to unscrew the retaining nut.
Pull out the old cartridge. Grasp the cartridge stem with pliers and pull straight up. Some cartridges are tight — rock them gently side to side as you pull. If it is stuck, use a cartridge puller tool or soak the area with penetrating oil for a few minutes.
Install the new cartridge. Apply a thin layer of plumber’s grease to the O-rings on the new cartridge. Align the cartridge properly (most have alignment tabs or marks) and push it in firmly. Secure it with the retaining clip or nut.
Reassemble the handle. Slide the handle back on and tighten the set screw or handle screw. Do not overtighten.
Test the repair. Turn the water supply back on and check for leaks. Run water through both hot and cold sides to ensure the cartridge is functioning correctly. If the faucet still runs, you may have a water pressure issue or a damaged valve body. This Old House offers a detailed visual guide on cartridge replacement.

Repairing a Ball-Type Faucet

Ball-type faucets have several small parts inside — the ball, springs, and rubber seals. If water runs continuously, one of these components is likely worn or misaligned.

Remove the handle. Look for a set screw on the side of the handle (often under a small plastic button). Use an Allen wrench to loosen it and lift the handle off.
Remove the cap and spout. Unscrew the decorative cap and lift off the spout. You’ll see a plastic or metal cam and cam washer underneath. Remove those parts and set them aside in order.
Lift out the ball. The rotating ball will come out easily. Inspect it for scratches, wear, or flat spots. If it looks worn, replace it.
Remove the springs and seals. Use a small screwdriver or tweezers to lift out the rubber seals and the springs beneath them. Replace all of them — these parts are cheap and often the cause of continuous running.
Install new parts. Place the new springs and seals in the correct positions, then set the ball back in place. Apply a thin layer of plumber’s grease to the cam washer and cam, and reassemble the cap and spout.
Reattach the handle. Secure the handle with the set screw.
Test the repair. Turn the water on and check for proper operation. Ball-type faucets can be finicky — if the handle is tight, you may need to adjust the cam or the set screw position.

Repairing a Ceramic-Disc Faucet

Ceramic-disc faucets are durable, but they are not immune to failure. A continuous run usually indicates debris between the discs or a cracked disc.

Remove the handle. Look for a set screw on the side or under a cap. Use an Allen wrench to remove it and pull off the handle.
Remove the escutcheon (the decorative plate). Unscrew the screws that hold the escutcheon in place and lift it off. You’ll see the cartridge housing beneath.
Remove the cartridge retaining screws. Typically, there are two or three screws holding the cartridge in place. Remove them carefully.
Lift out the ceramic cartridge. The cartridge contains the discs. Do not take the cartridge apart — it is a sealed unit. If it is damaged, replace it entirely. If debris is the issue, you may be able to flush it out with water, but replacement is more reliable.
Install the new cartridge. Place the new cartridge in the correct orientation (alignment marks are usually present). Secure it with the retaining screws, and reassemble the escutcheon and handle.
Test the repair. Turn the water on and check for leaks. If the faucet still runs, the issue may be in the valve body itself, and you may need to call a professional.

Testing Your Repair Thoroughly

After reassembling the faucet, turn the water supply valves counterclockwise to restore flow. Open the faucet fully for a few seconds to flush out any debris and to let the components seat properly. Then close the faucet and watch for any drips or continuous running. Wait at least two minutes — sometimes a slow leak takes a moment to appear.

If you notice moisture around the handle or the base of the spout, you may have an O-ring that is not seated correctly or a nut that is not tight enough. Turn off the water, tighten the packing nut or retaining nut slightly, and test again. Be careful not to overtighten, which can crack plastic components or strip threads.

If the water still runs after a thorough repair, double-check that you installed the correct replacement parts. Using the wrong size washer or a generic cartridge can cause a poor seal. If you are certain the parts are correct, the problem may be deeper — a damaged valve seat, a cracked valve body, or a supply line issue. In such cases, consult a professional plumber.

When to Call a Professional Plumber

Not every sink repair is a DIY project. You should consider calling a licensed plumber if:

The water supply valves under the sink are stuck, corroded, or broken, and you cannot turn off the water.
You have disassembled and reassembled the faucet with the correct parts, but the water still runs continuously.
You suspect a cracked valve body or a leak inside the wall.
Your home has high water pressure (above 80 psi) that may be damaging faucet components repeatedly. A plumber can install a pressure regulator to protect your plumbing system.
The faucet is under warranty and requires manufacturer-authorized service. Attempting a DIY repair could void the warranty.
You are uncomfortable working with plumbing and prefer professional assurance.

Even a simple call to a pro can save you from water damage and costly repairs down the line. According to Angi (formerly Angie’s List), the average cost for a professional faucet repair ranges from $150 to $350, depending on the complexity and parts needed.

Preventing Future Problems

Preventive maintenance is the best way to avoid a continuously running sink. Here are practical steps you can take to extend the life of your faucet and its internal components.

Replace Worn Parts Early

If you notice a small drip or a handle that requires more effort to turn, address it promptly. A minor leak often means a washer or O-ring is beginning to fail. Replacing it early costs pennies and takes minutes. Letting it go will only worsen the wear on the valve seat and other parts.

Clean the Faucet Aerator Regularly

Sediment and debris can build up inside the aerator (the small screen at the tip of the spout). This buildup can cause pressure imbalances that affect how the faucet shuts off. Unscrew the aerator every few months, rinse it out, and scrub away any mineral deposits with a small brush or vinegar soak.

Maintain Proper Water Pressure

High water pressure is hard on faucet seals and can cause them to fail prematurely. The ideal home water pressure is between 40 and 60 psi. You can test your pressure with a simple gauge that screws onto a hose bib. If it is consistently above 80 psi, have a plumber install a pressure-reducing valve. The EPA’s WaterSense program has resources to help you manage water pressure and save water.

Use the Faucet Gently

Slamming the handle shut or using excessive force can crack cartridges and wear out O-rings. Teach everyone in your household to operate the faucet smoothly. Avoid hanging heavy items on the faucet handle or using it as a lever.

Flush the Water Lines After Repairs

Anytime you shut off the water and then restore it, air and debris get stirred up. Before fully using your faucet after a repair, let it run for a minute or two with the aerator removed. This flushes out any loose sediment that could clog the new cartridge or washer.

Schedule an Annual Inspection

Once a year, take a few minutes to inspect your faucets. Look for dampness under the sink, check for drips, and listen for any hissing sounds. A quick visual check can catch a problem before it becomes a continuous run. Keep a set of basic replacement parts (washers, O-rings, a common cartridge) on hand so you can make a repair immediately.

Final Thoughts on Fixing a Continuously Running Sink

A sink that won’t stop running is rarely a catastrophic problem. In the vast majority of cases, it is caused by a single small component that has simply reached the end of its useful life. With the right tools, a bit of patience, and the steps outlined above, you can restore your faucet to proper working order in an hour or two. Not only does that save you the cost of a service call, but it also gives you a reliable, long-lasting fix.

If you encounter any step that feels beyond your comfort level — especially if you are dealing with corroded valves or a complex cartridge system — do not hesitate to call a professional. Plumbing repairs are a worthwhile investment when they prevent water damage and frustration. By understanding how your faucet works and performing regular maintenance, you can keep your sink running only when you intend it to.