A leaking faucet almost always comes down to one worn part, and which part depends on which of four mechanisms is inside the handle: compression, cartridge, ball, or ceramic disc. Shut off the water under the sink, pull the handle, and the mechanism tells you instantly which one you have. Compression faucets use a rubber washer that hardens with age; the other three are “washerless” designs that rely on O-rings, seals, or springs instead, and each has its own failure point. Once you know which type is dripping, the fix is usually a $5–15 part and twenty minutes, no different in principle from the dye test that diagnoses a running toilet.
How do I know what type of faucet I have?
Handle count is a clue, not proof: compression faucets always have two handles, but cartridge and ball faucets can have one or two, and ceramic disc faucets are almost always single-handle. The reliable check is to turn off the water, pull the handle, and look at what is underneath, following the same approach Cal Poly’s housing repair guide walks through for student apartments.
| Type | Handles | What you see inside | Usual failure |
|---|---|---|---|
| Compression | Two (hot/cold) | A threaded stem with a rubber washer at the tip | Washer hardens or tears |
| Cartridge | One or two | A removable plastic or brass cylinder | O-rings on the cartridge wear out |
| Ball | One, on a rounded cap | A slotted metal or plastic ball with springs | Springs, seats, or O-rings degrade |
| Ceramic disc | One, usually tall | Two stacked ceramic discs | Mineral grit scores the discs, or the neoprene seal wears |
Parts are rarely interchangeable between brands, so once you have the type confirmed, take the worn part (or a photo of it) to the hardware store rather than guessing at a repair kit.
How do you fix a leaking compression faucet?
- Shut off the hot and cold supply valves under the sink and open the faucet to drain the lines.
- Pry off the decorative cap on the handle, remove the screw underneath, and lift the handle free.
- Use an adjustable wrench to unscrew the packing nut, then lift out the stem.
- At the bottom of the stem is a brass screw holding a rubber washer in place. Remove the screw, swap the washer for an exact match (washers are sold by diameter, not universally), and reattach.
- While it is apart, check the O-ring around the stem itself; if it feels flat or cracked, replace that too, since it is a common second leak point that a washer swap alone will not fix.
- Reassemble in reverse order, hand-tighten the packing nut, and turn the water back on slowly while watching for drips at the handle base.
A compression stem that still drips from the spout after a new washer usually means the valve seat itself, the ring the washer presses against, is pitted. A seat-dressing tool can resurface a light seat, but a badly pitted one needs a plumber or a full stem-and-seat replacement kit.
How do you fix a leaking cartridge faucet?
Cartridge faucets fail less predictably than compression ones, because the whole cylinder is sealed and any of several O-rings inside it can be the culprit. Replacing the entire cartridge rather than individual seals is the standard fix.
- Turn off the water and pop off the handle’s index cap to reach the screw.
- Remove the handle, then the retaining clip or threaded collar that holds the cartridge in the faucet body. Note which way the cartridge faces before pulling it, since reinstalling it backwards swaps hot and cold.
- Pull the cartridge straight up. Mineral buildup can seize it; a dedicated cartridge puller, or gentle twisting with pliers on a protected cartridge, usually frees it.
- Coat the O-rings on the new cartridge with plumber’s grease, seat it in the same orientation as the old one, and replace the clip or collar.
- Reattach the handle and restore water slowly, checking for leaks at the base of the spout and underneath the sink.
Keep the old cartridge or its model number; cartridges are brand- and sometimes model-specific, and a close-but-wrong substitute will leak again within weeks.
How do you fix a leaking ball faucet?
Ball faucets, common on single-handle kitchen sinks, use a slotted ball that rotates inside a dome to mix hot and cold. Several small rubber seats and springs press against that ball, and any one of them can wear out.
- Shut off the water, then remove the handle’s set screw (often reached with a small hex key) and lift the handle off.
- Unscrew the domed cap and the plastic cam assembly beneath it, then lift out the ball itself.
- Inspect the ball for scratches or chips; a damaged ball needs replacing, not just its seals.
- Use needle-nose pliers to pull the small spring-loaded rubber seats and springs from the faucet body, and swap in the matching parts from a ball faucet repair kit, which bundles the ball, cam, springs, seats, and O-rings together.
- Reassemble in order: springs and seats, ball, cam, cap, then handle.
Because a ball faucet has more individual wear parts than the other three types, replacing the full repair kit rather than chasing one leaking seat usually buys more time before the next teardown.
How do you fix a ceramic disc faucet that still drips?
Ceramic disc faucets, recognizable by a wide cylindrical body under a single handle, rarely fail outright, but they are not leak-proof. Two polished ceramic discs slide across each other to open and close the water path, and grit between them, rather than a worn seal, is the most common cause of a slow drip or weak flow.
- Turn off the water, remove the handle, and lift out the disc cartridge, usually held by two or three screws.
- Flip the cartridge over and inspect the ports and disc faces for mineral scale or a stuck piece of grit. Soak in white vinegar for 15–20 minutes to dissolve scale, then rinse.
- Check the neoprene seals on the underside, the actual rubber parts in this design; if they are flattened or torn, replace them even if the discs look fine.
- Reinstall the cartridge, screw it down evenly, and restore the water.
If cleaning does not stop the drip, the discs themselves are likely scratched and the cartridge needs replacing as a unit; the ceramic discs are not sold separately from most cartridges.
How much water does a leaky faucet actually waste?
A faucet that drips about once per second wastes more than 3,000 gallons (11,350 liters) a year, according to the EPA WaterSense Fix a Leak Week fact sheet, and EPA estimates that leaks of all kinds add up to more than 10,000 gallons (37,850 liters) wasted in the average home every year. The exact number for any one faucet depends on drop size, which is why figures in other sources vary widely: the US Geological Survey’s drip calculator notes there is no fixed scientific definition of a “drop,” and its own working assumption, about a quarter-milliliter per drip, is just one of several reasonable estimates. Treat any single number as a rough order of magnitude rather than a precise reading of your own faucet.
| Drip you notice | Rough yearly waste | What usually causes it |
|---|---|---|
| Faucet closes fully, no sound | None | Not actually leaking |
| Occasional drop, often after use | Low hundreds of gallons | Worn O-ring, slow to reseat |
| Steady drip, roughly once a second | 3,000+ gallons (EPA estimate) | Worn washer, cartridge seal, or disc grit |
| Thin but constant trickle or stream | Several thousand gallons or more | Pitted valve seat, failed cartridge, cracked disc |
A dripping hot-water faucet wastes energy as well as water, which is the same logic behind setting your water heater to an efficient temperature: heating water that then runs down the drain is pure waste on both utility bills at once.
Is it better to repair an old faucet or replace it?
Most leaks are cheaper to repair than to replace, especially compression and cartridge types where parts are inexpensive and widely stocked. Replacement starts to make more sense once a faucet is corroded at the base, the finish is worn through to bare metal, or it needs a second or third repair within a few years, since that pattern usually means the valve seat or faucet body itself is failing rather than a single seal. If you are replacing rather than repairing, look for the WaterSense label: a WaterSense-certified bathroom faucet flows at 1.5 gallons per minute or less, about 30 percent below the 2.2-gallon-per-minute baseline most older faucets are built to, according to EPA’s bathroom faucets page, so an upgrade saves water on every use, not only once the leak is fixed.
Call a plumber rather than continuing to take a faucet apart if water is pooling under the sink even with the faucet off (that points to a supply-line or shutoff-valve leak, not the faucet itself), if the faucet body is cracked, or if you have already replaced the obvious wear part and it still drips from the spout, which usually means a seat or body problem beyond a parts swap. Oklahoma State University Extension frames this kind of small repair as one of the simplest ways a household cuts both its water bill and the strain on local supply, alongside habits like turning off the tap while brushing your teeth. A fixed faucet is also a good moment to check the rest of the house: a running toilet wastes far more water than any dripping tap, and if you are already thinking about where your water goes, a rainwater harvesting system is worth sizing up for outdoor use once the indoor leaks are gone.