A dripping tap is a worn $2 washer or a $15 cartridge, never a mystery. Identify the type, shut the water, and the swap is 30 minutes with two tools.
Riley Brand
Two separate hot and cold handles that tighten down with multiple turns: compression - the oldest type, sealed by rubber washers, and the one that drips most. Two handles that move a quarter-turn between off and full: ceramic disc cartridges. A single lever: either a cartridge, a ball (mostly older kitchen mixers, identifiable by a domed cap under the lever), or a ceramic disc mixer.
The diagnosis shortcut: where the water comes from matters too. Drip from the spout means the internal seal (washer, cartridge, or springs) has failed; leak around the handle or base means O-rings. Either way the cure is replacing the soft parts, and the parts cost pocket change - it is identification, not skill, that decides whether this takes 30 minutes or three trips to the store.
Close the isolation valves under the sink (slot-head or small lever on each supply pipe - quarter turn), or the main stop valve if there are none. Open the tap fully to drain the last water and confirm the shutoff actually holds. Then plug the drain with a rag - the single best tip in tap repair, because every small screw wants to go down that hole.
Lay parts out in removal order on a towel, photograph each step on your phone, and line the wrench jaws with tape before touching any chromed nut. Reassembly is the reverse of the photos, and taped jaws are why your tap will not wear tooth scars afterward.
Pry off the handle's decorative cap, remove the handle screw, and pull the handle. Unscrew the headgear nut below with an adjustable wrench (steady the tap body with your other hand so you do not twist the whole fitting), and lift the valve stem out. At its base sits the culprit: a rubber washer held by a small screw or pressed into a recess.
Replace it with a matching size - half-inch is most common; take the old one to the store, or buy a mixed washer box for a couple of dollars and have every size forever. While it is open, inspect the O-ring on the stem (replace if flattened) and feel the valve seat inside the tap body: if it is rough or pitted, the new washer will fail early - a $10 seat-grinding tool resurfaces it in two minutes. Reassemble, snug but not gorilla-tight, and test.
Same start: cap, handle screw, handle off. Beneath sits a retaining nut or clip holding the cartridge; unscrew or unclip it, note the cartridge's orientation (photograph it - many only seat one way, and hot/cold reverse if you guess), and pull the cartridge straight up, with pliers if snug.
Match the replacement exactly - brand and model matter here, so take the old cartridge to the store or search its markings online; common ones cost $10 to $25. Smear the new O-rings with plumber's silicone grease (not petroleum jelly, which degrades rubber), seat it in the noted orientation, and reassemble. Quarter-turn ceramic taps almost never need anything else for a decade.
Reopen the isolation valves slowly, then run the tap through its range and watch the spout and base dry-handed for a minute. A new drip from the base usually means an O-ring pinched during assembly - open it back up and reseat rather than over-tightening, which cracks ceramic and strips brass.
Call time on DIY when: the shutoff valves themselves will not close (replacing those is a bigger job), anything is seized so hard it threatens to twist the pipework, the tap body itself is cracked or corroded through, or it is a fancy thermostatic mixer under warranty. A persistent drip after two correct part swaps usually means the valve seat or tap body is worn out - at which point a new tap (often $30-60) beats further surgery.
Take the old part to the hardware store - it is the only method that never fails. For cartridges, the brand name on the tap plus a photo of the cartridge usually finds the exact match online within minutes.
Almost always a worn valve seat - the brass ring the washer presses against. A rough seat chews new washers within weeks. A seat-grinding tool ($10) resurfaces it, or use a domed washer as a stopgap. If the seat is badly pitted, the tap is at end of life.
One drip per second wastes roughly 25-30 litres a day, which adds up on a meter - and hot-side drips waste the energy that heated the water too. The fix costs $2 and 30 minutes; the drip costs more every month it continues.
An adjustable wrench, a flat and a Phillips screwdriver, tape to pad the wrench jaws, a rag for the drain, and silicone plumber's grease. A mixed washer/O-ring assortment box turns most future drips into a zero-shopping fix.
