Why Is My Faucet Dripping?
A dripping faucet is almost never random — it means something inside the valve has stopped sealing properly. In most modern faucets that means a worn or damaged cartridge, a hardened O-ring, or grit and limescale trapped against the valve seat, so water keeps finding a path through even when the handle is fully closed. Pressure spikes and loose connections cause drips too, but less often.
How Do I Know If the Cartridge Is Worn Out?
A worn cartridge is the most common reason a faucet drips, especially in single-handle mixers used daily for several years. Inside the cartridge, two ceramic discs (or a rubber-and-spring mechanism in older designs) slide against each other to open and close the water path; once that surface wears down or scratches, it can no longer form a tight seal, so water seeps past it even when the handle is off.
You'll usually notice the drip getting worse over weeks or months rather than appearing suddenly, sometimes paired with a handle that feels looser or harder to turn fully off. Ceramic-disc cartridges, now standard in most quality faucets, resist wear far better than older rubber-seat designs, but no cartridge lasts forever under constant use. Replacing the cartridge — rather than the whole faucet — solves this type of drip in nearly all cases.
Why Do the Rubber Seals or O-Rings Fail?
Beyond the cartridge itself, faucets rely on small rubber O-rings and washers to seal the spout, the handle stem, and the connection points where water enters the body. These rubber parts harden, crack, or compress with age and heat exposure, losing the elasticity that once created a watertight seal. When an O-ring fails, water typically drips from the base of the spout or leaks around the handle rather than from the spout tip.
Seal wear is accelerated by hot water, hard-water minerals, and simple age — most O-rings are only rated for a few years of continuous service. If the drip is coming from around the handle base or where the spout meets the body rather than straight down from the outlet, a perished O-ring is a more likely culprit than the cartridge, and it's usually the cheaper, simpler fix of the two.
Can Limescale or Debris Cause a Drip?
Yes — in hard-water areas, mineral deposits build up inside the cartridge and around the valve seat, preventing the internal surfaces from closing flush against each other. Tiny particles of sediment, sand, or old solder from the pipes can do the same thing by physically wedging themselves between the sealing surfaces. Either way, the cartridge can't fully shut even though it isn't actually broken, and water drips continuously or only under certain pressure.
This is the drip that often responds to cleaning rather than replacement: removing the cartridge, soaking it in a descaling solution or vinegar, and clearing any visible grit can restore a full seal. It's also why a new drip appearing right after plumbing work — a repair, a new water heater, or the water being shut off and turned back on — is often debris knocked loose into the line rather than a new mechanical failure.
Does Water Pressure Affect Dripping?
High or fluctuating water pressure can force tiny amounts of water past a cartridge or seal that would otherwise hold, especially one that's already slightly worn but not yet fully failed. Pressure spikes, common in buildings with municipal supply surges or a faulty pressure-reducing valve, put extra stress on every seal in the system, and faucets are often the first place a pressure problem shows up as a persistent, hard-to-explain drip.
If several fixtures in the home drip, or a drip appears only at certain times of day, unusually high supply pressure is worth checking before replacing any parts — a plumber can test it in minutes with a simple gauge. Installing a pressure-reducing valve, where household pressure runs consistently above normal, often stops drips from recurring even right after a cartridge has been replaced.
Could Loose or Worn Connections Be the Cause?
A drip isn't always coming from inside the valve — a loosened packing nut, a worn supply-line connection, or a fitting that was never fully tightened can let water seep out at a joint and travel down to the spout or drip underneath the sink. This type of leak often shows up as dampness at the base of the faucet or inside the cabinet rather than water actually falling from the spout outlet.
Tightening the packing nut beneath the handle or the connections at the supply lines with a wrench solves this in minutes and costs nothing, so it's worth checking before assuming the cartridge has failed. Over-tightening can crack fittings, though, so snug is enough — if a properly tightened connection still leaks, the washer or seal inside that fitting has likely worn out and needs replacing.
Cartridge Replacement or a New Faucet — Which Do I Need?
A drip from a faucet that's otherwise in good shape — no corrosion, no cracks in the body, no rust at the base — almost always calls for a cartridge replacement, not a new faucet; cartridges are inexpensive and widely available for most standard mixer designs. Replace the whole faucet instead when the body itself is cracked, badly corroded, or leaking from the base into the counter or cabinet, or when it's an older model whose cartridge is no longer made.
Faucets built around a replaceable ceramic-disc cartridge — the construction Susan and most modern brass-body mixers use — make this an easy call, since the cartridge is designed as a wear part while the body should outlast several cartridges over its service life. If a faucet is more than 15–20 years old, uses an obsolete rubber-seat mechanism, or has visible corrosion at the base, chasing down a matching cartridge can end up costing close to a new faucet anyway.
Can I Fix a Dripping Faucet Myself, or Should I Call a Plumber?
Most dripping faucets are a reasonable DIY job: shutting off the water supply, removing the handle and cartridge, and swapping in a matching replacement typically takes under an hour with basic tools and no special skills. Call a plumber instead when you can't identify or find the correct cartridge, when the shutoff valve itself is stuck or leaking, when there's any sign of water damage behind the wall or under the cabinet, or when a supply-line connection won't seal no matter how it's tightened.
Before buying a replacement cartridge, remove the old one and match it by brand and model rather than by appearance, since cartridges from different faucets are rarely interchangeable even when they look similar. If the drip returns within days of a cartridge swap, the problem is more likely debris, pressure, or a connection issue than the part itself, and that's a good point to bring in a plumber rather than keep guessing.
Frequently Asked Questions
Why is my faucet dripping even when it's fully turned off?
This almost always means the cartridge or an internal seal is no longer sealing completely, letting a small amount of water pass through even in the closed position. Mineral deposits or trapped debris can cause the same symptom without any part actually being broken.
How much does it cost to fix a dripping faucet?
A replacement cartridge is a low-cost part, and if you do the swap yourself the job costs little beyond the part itself. Hiring a plumber adds a labor charge, but the repair is usually far cheaper than replacing the entire faucet.
Why does my faucet only drip at night?
Water pressure in municipal systems often rises overnight when overall demand drops, and that higher pressure can push water past a cartridge or seal that holds fine during the day. A drip that appears only at night points toward pressure rather than a fully failed part.
Is a dripping faucet actually wasting much water?
A slow, steady drip can add up to a noticeable amount of wasted water over weeks, even if each individual drop looks insignificant. It's also often an early sign that a seal is failing, so fixing it promptly avoids a bigger leak later.
Can I replace a faucet cartridge without turning off the main water supply?
You only need to close the shutoff valves under the sink, or the fixture's own isolation valves if it has them — the home's main supply doesn't need to be shut off for a cartridge swap. If there's no local shutoff, closing the main line is the safer option.
Why is my faucet dripping from the spout even though the handle is off?
Water dripping straight down from the spout with the handle fully closed points to the cartridge itself, since that's the part responsible for sealing the water path shut. If the drip instead comes from around the base or handle, an O-ring or connection is the more likely cause.
How do I know which cartridge to buy for my faucet?
Remove the handle and the old cartridge, then match it by the brand and model stamped on it or on the faucet body rather than by its shape alone, since many cartridges look similar but aren't interchangeable. Bringing the old cartridge to a hardware store is the most reliable way to get an exact match.