Faucet Keeps Dripping? The Hidden Part You Missed
Quick Answer: A faucet that keeps dripping after you have already tried the obvious fix usually has a worn part you cannot see from the handle: a pitted valve seat, a hairline crack in a cartridge, a flattened O-ring, or a scored ceramic disc. Water pressure and hard-water scale speed all of it up. The fix depends on which faucet type you have, and a fresh rubber washer alone often will not solve it.
Why The Drip Comes Back After You Fix It
You tighten the handle. You swap the washer you found at the hardware store. For a day, silence. Then the slow tap-tap starts again at 2 a.m. The drip is not stubborn out of spite. It comes back because the part you replaced was a symptom, not the cause.
A faucet is a valve. Somewhere inside, a moving piece presses against a fixed piece to stop the flow. When those two surfaces no longer meet cleanly, water sneaks through. Replacing one half of that pair while ignoring the other is like putting a new gasket on a warped lid: the new part deforms to match the damaged surface it seals against, and the leak returns.
The first job is figuring out which of the four faucet types you own, because each one wears out in a different place.
The Four Faucet Types And The Part That Fails In Each
You can usually tell the type by the handles and how they move.
Compression faucets (two handles, they get harder to turn as they close): These are the oldest design and the most common source of a classic drip. Inside each handle, a threaded stem screws down and presses a rubber washer against a metal valve seat. Close the tap, and the washer squashes flat against the seat to block flow.
The washer is soft on purpose, so it wears first. It flattens, cracks, or hardens with age. That is the part most people replace. But the seat it presses against, a small brass ring down in the faucet body, corrodes and pits over years of hard water. A pitted seat has tiny craters in it, and no washer can seal against a cratered surface for long.
Cartridge faucets (single or double handle, smooth turn end to end): A cartridge is a self-contained plastic-and-rubber sleeve that lifts and rotates to control flow and temperature. When it drips, the culprit is usually a hairline crack in the cartridge body or worn internal seals. You rarely rebuild a cartridge. You pull the old one and drop in a matching replacement.
Ball faucets (single handle that pivots on a rounded cap, common on kitchen sinks): A slotted metal or plastic ball sits over spring-loaded rubber seats. As you move the lever, the ball's holes line up with the inlet ports. Drips here usually trace to the springs losing tension or the small rubber seats under them wearing down, so the ball no longer presses tight.
Ceramic disc faucets (single lever, feels solid and modern): Two polished ceramic discs slide across each other. One rotates, one stays fixed, and their aligned slots meter the water. Ceramic is extremely hard and lasts for years, but grit and mineral scale can score the polished faces, and a scored disc no longer seals flush.
Why A New Washer Alone Sometimes Does Nothing
Here is the trap that sends people back to the store three times. On a compression faucet, the washer is the cheap, easy part to swap. So you swap it. It works for a week, then drips again, sometimes worse.
The reason is the valve seat. Once that brass seat is pitted, its cratered surface acts like sandpaper against the fresh rubber. Every time you close the tap, the ruined seat chews a groove into the new washer within days. You are not fixing the leak; you are feeding it new washers to destroy. A seat in that condition has to be resurfaced with a seat-dressing tool or swapped for a new one before any washer can hold.
On a compression faucet, inspect the valve seat, not just the washer. Run a fingertip inside the faucet body; if it feels rough or gritty, the seat is pitted, and a fresh washer will not hold until the seat is resurfaced or replaced.
O-Rings: Base Leaks Versus Spout Drips
Not every leak comes out of the spout. Pay attention to where the water actually shows up, because it points to a different part.
If water pools around the base of the spout or seeps out where the handle meets the body, the suspect is usually an O-ring, a small rubber loop that seals the joint between two moving pieces. O-rings flatten and dry out, and once they lose their round cross-section, they let water weep past.
If the drip falls from the spout tip when everything is turned off, you are back to the sealing surfaces inside: the washer and seat, the cartridge, the ball's rubber seats, or the ceramic discs. Sorting a base leak from a spout drip before you open anything tells you which part to have ready.
The Two Culprits That Wear Everything Out Faster
Two forces attack every faucet type at once, and they explain why some homes go through parts far quicker than others.
High water pressure: Household pressure should generally sit in a moderate range. When it runs high, every seal in the house takes a constant pounding, and faucet washers, cartridges, and O-rings give out early. A related problem is water hammer, the banging you hear when you shut a tap fast. That shock wave slams the internal seals and can leave a faucet dripping right after the noise. A pressure-reducing valve at the main and arrestors on the lines calm both.
Hard-water scale: Hard water carries dissolved minerals that crust into a chalky scale on every wet surface. That scale roughens valve seats, jams cartridges, and grinds against ceramic discs like fine sand. It is the quiet reason a faucet that lasted a decade at one house wears out in a couple of years at another with harder water.
Shut The Water Off First, Then Work In Order
Before you loosen a single screw, close the two shut-off valves under the sink, then open the faucet to bleed off the pressure and confirm the flow has stopped. Skipping this step turns a slow drip into a soaked cabinet in seconds.
A sensible order of attack:
- Confirm the leak point (spout versus base) so you know whether to chase seals or O-rings.
- Identify your faucet type from the handles.
- For a compression faucet, inspect the seat, not just the washer. Run a fingertip inside; if it feels rough or gritty, the seat is pitted and the washer will not hold until the seat is resurfaced or replaced.
- For a cartridge, ball, or ceramic disc faucet, match the exact replacement part to your model before you start, since these are not universal.
- Reassemble hand-tight, then snug gently. Do not crank down on the handle or packing nut. Overtightening cracks plastic cartridges, splits brass, and can shatter a fixture, which turns a cheap repair into a full replacement.
When To Repair, When To Replace The Whole Faucet
A single worn washer, O-ring, or cartridge in an otherwise solid faucet is worth repairing. The parts are inexpensive, and the faucet body is fine.
Lean toward replacing the whole faucet when the body itself is corroded, when the finish is flaking, when the same faucet has needed three or four repairs in a year, or when you cannot find replacement parts for an older model. A faucet that keeps failing in new places is telling you its internals have reached the end.
Some jobs point straight to a professional. A shut-off valve under the sink that will not turn, or itself leaks, is a repair you should not force, because a snapped valve floods the cabinet. A supply line weeping at its connection, a drip that persists after you have rebuilt or replaced the internal parts, or a faucet you cannot get apart without risking damage are all signs to bring in a plumber rather than keep wrenching. A pro can also test your home's pressure and check for water hammer, the upstream causes that keep eating faucets no matter how many washers you feed them.
Frequently Asked Questions
You can thread an inexpensive water-pressure gauge onto an outside hose bib or a laundry connection and read it directly. Household pressure above roughly 80 psi is generally considered too high and stresses fixture seals; many gauges have a red lag needle that records the peak overnight, which catches pressure spikes you would otherwise never see.
Yes, more than most people expect. A faucet dripping once per second wastes on the order of several thousand gallons over a year. A steadier drip that fills a coffee cup in ten minutes runs into the tens of thousands of gallons annually, which shows up as a slow, unexplained creep in monthly usage.
That points to thermal expansion, a factor not covered above. When a water heater heats a tank, the water expands and briefly raises pressure throughout the system. On a closed plumbing system, that pressure spike has nowhere to go and can push past a marginal seal, so you see a drip only during heating cycles. A properly sized thermal expansion tank absorbs it.
For rubber seals, it matters. A dab of silicone-based plumber's grease, not petroleum jelly, on a new O-ring or cartridge helps it slide into place without tearing and keeps the rubber pliable so it seals evenly. Petroleum products swell and degrade rubber over time, so the type of grease is not a small detail.
Not usually. A drip from the aerator tip after shut-off often traces to a diverter valve or check valve inside a pull-out or sprayer faucet failing to reset, or trapped water draining from the hose. Cleaning or replacing the aerator screen and checking the diverter usually resolves it, separate from the washer-and-seat repair.
Just the fixture valves, but do two things first. After closing them, open the faucet and let it run dry to bleed the pressure trapped in the line, then leave it open so any residual seepage drips into the basin instead of spraying when you pull the cartridge. Know which valve you have too: a modern quarter-turn ball stop seals with a 90-degree flip, while an older multi-turn compression stop can need several full turns and its own washer may weep once it is worked, which is why plumbers often plan to swap a tired angle stop at the same visit rather than trust it a second time.
Book a drip diagnosis before it soaks the cabinet — a pro finds the worn seat, cartridge, or pressure problem your washers keep hiding. Ser Plumbing serves Paramount, Bellflower, Lakewood. Call (310) 735-3532.
