A slow drip from a faucet can be maddening and wasteful, and it tends to show up at the worst possible moment. Many people chalk it up to tired plumbing, but a handful of specific mechanical issues usually sit at the root.
Some leaks are simple to fix with a few tools and a replacement part, while others require a steadier hand or professional help.
Faucet types and how they leak
Not all faucets behave the same when they spring a leak, and the internal design matters a lot. Compression-style taps use a washer that presses down to stop flow, so wear shows up as a steady drip more often than in other types.
Cartridge, ball, and ceramic disc faucets have different moving parts and seals, and the failed component depends on the model. Knowing what type you have makes troubleshooting far less like poking around in the dark.
Worn washers in compression faucets
A worn rubber washer is a classic cause of a drip in older, compression-style faucets and happens from repeated contact and friction. The circular washer flattens, hardens, or tears, and water slips past the seat even with the handle turned down.
Replacing that washer is usually cheap and quick, and it often restores a dry spout with a modest amount of elbow grease. If the tap still leaks after a swap, check the valve seat for rough spots that could grieve a new washer.
Faulty cartridges and seals
Cartridge faucets rely on a central moving block to route hot and cold flow, and a damaged cartridge or failing seals will let water leak. Rubber gaskets and O-rings on the cartridge wear out from chemical attack, heat, and normal motion, creating paths for a drip.
Swapping the cartridge or replacing the seals typically cures the problem, though some brands need the exact factory part to fit right. When parts are hard to match, taking the old cartridge to a parts counter helps you avoid buying the wrong thing.
Corroded valve seat
The valve seat is the metal surface the washer or cartridge seals against, and corrosion there can produce an uneven surface that refuses to close. Sediment and mineral shards hammer at that seat over months or years, leaving pits and grooves that let a trickle pass.
A resurface or new valve seat can restore a proper seal, yet deep damage might call for more extensive plumbing work. Matching the repair method to the damage level keeps the fix from being a short-term patch.
Mineral buildup and hard water
Mineral deposits form scaly crusts inside faucet paths, and these crusts change how parts move and seal together. Hard water leaves behind limescale that gums up seals, prevents cartridges from seating, and blocks tiny channels in disk faucets.
A soak in a mild acid solution or mechanical removal often clears the build-up, after which the faucet may behave like it once did. Keeping mineral under control with simple filters or softening systems cuts down on repeat problems.
High water pressure and thermal expansion
High pressure in the household supply can put constant stress on seals and joints, coaxing a drip out of a marginally healthy faucet. Thermal expansion — water heating and pressing against a closed valve — adds short bursts of pressure that worsen persistent leaks.
Installing a pressure regulator or an expansion tank reduces internal stress and takes pressure off seals and threads. Lowering pressure also saves water and gives a quieter, longer-lived system, which feels like killing two birds with one stone.
Loose parts and fittings
A faucet that drips when off might be hiding a loose part somewhere inside the assembly or along the supply line connection. Vibrations, thermal cycles, and aging hardware let nuts and packing slip a fraction out of place, creating slow leaks that start small and grow larger.
Tightening connections and checking the mounting hardware under the sink is a quick first step that often pays off. If tightening does nothing, inspect for cracked fittings or threads that have been chewed up.
Damaged O-rings and seat seals
O-rings are small, cheap pieces that do heavy lifting by sealing moving parts, and they wear out in ways that make a dripping tap act up intermittently. A collapsed O-ring will leak when the handle rests one way, or leak constantly if it fails completely, which can be maddening to track down.
Replacing O-rings with lubricated replacements usually smooths operation and stops the seep. Keep a few spare rings on hand; they are the kinds of parts that save a plumbing trip in the late hours.
Aerator leaks versus internal leaks
Before you strip a faucet, check the aerator at the spout tip since a loose or damaged aerator can look like an internal leak but is simple to fix. Remove the aerator, clean out debris or mineral fragments, and hand-tighten it back on; many “drips” disappear at that moment.
If water still trickles with the aerator removed, the path is inside the faucet body and requires a closer look. Distinguishing the two saves time and keeps repairs focused where they belong.
Basic DIY troubleshooting steps
Start by shutting off the water at the supply valves under the sink, which makes the job safer and cleaner and keeps surprise sprays at bay. Next, remove the handle and inspect the internals visually for obvious wear, mineral buildup, or loose parts; take pictures so reassembly won’t feel like a puzzle.
Swap simple wear parts like washers, O-rings, and cartridges if you have the right sized replacements, testing the faucet as you go. If the leak proves stubborn or the work feels beyond your comfort zone, pack up your findings and call a plumber who can follow up without guesswork.
When a professional should handle it
Persistent leaks that resist basic fixes, visible water damage in cabinets, or corrosion of supply lines are signs to pass the baton to a licensed plumber. Complex issues such as corroded valve seats, cross-threaded fittings, and damage inside wall-mounted systems often need specialized tools and parts to repair without compounding the harm.
If you’re dealing with inconsistent flow or suspect hidden plumbing faults, you can always count on this plumber solving low water pressure and related leak problems efficiently.
A plumber will also advise on pressure regulation, replacement options, and warranty concerns so you are not chasing the same leak down the line. Hiring a pro can be a smart saving move when temporary fixes would only buy a short reprieve.
Preventative maintenance to cut leaks
Regular brief inspections and light maintenance make leaks less likely and save water and stress over the long haul. Clean aerators, flush lines when you do major home projects, and swap wear parts every few years if the faucet gets heavy use.
Installing a mild water treatment and watching household pressure keeps seals and seats out of harm’s way, which lengthens the interval between repairs. A little care goes a long way, turning drip management from a recurring headache into a manageable chore.