By the FaultToFix team | Published: 27 October 2026 | Last updated: 27 October 2026
DIY level: Easy to moderate · Cost: $0 to test, $2–$20 to fix, $15–$45 for a cartridge · Time: 10 minutes to test, 30–60 minutes to fix
Quick Answer: If your faucet still drips after a new washer, the washer was probably never the whole fault. A washer seals by pressing against a brass valve seat, and if that seat is scored, pitted, or corroded, no washer — old or new — will seal against it. The other common cause is the wrong part entirely: a cartridge faucet has no washer to change. Work through the two free checks below (drip pattern, then faucet type) before buying anything else, and you will know in 10 minutes whether you need a seat repair, a cartridge, or a new faucet.
Key Takeaways
- New washer, same drip = check the valve seat first. A scored seat lets water past a perfect washer.
- A steady, constant drip points to the seat or cartridge; a drip that only follows use points to water left in the spout. Do not confuse the two.
- Identify the faucet type before buying parts: a handle that keeps winding is a compression (washer) faucet; a handle that stops after a quarter or half turn is a cartridge faucet — and a cartridge faucet has no washer inside.
- A seat can be dressed with a reseating tool or replaced, but a cracked seat or a corroded valve body is a replacement job, not a repair.
- Measure the cartridge before ordering a replacement — spline count and length, not “looks about right”. The wrong cartridge is the most common second wasted purchase.
Jump to a Section
- Confirm the diagnosis · Symptom → cause table · What you need · The fix, step by step · If that didn’t fix it · When to replace the faucet instead · Common mistakes · When to stop and call a pro · Cost table · US / UK term box · FAQs · Checklist
Safety box
Everything in this guide happens with the water turned off at the shutoff valves under the sink, and the faucet opened to release pressure before any part comes out. You never cut, solder, or re-pipe anything, and you never force a seized valve or a corroded fitting. If a shutoff valve is seized, weeping, or missing, stop and use the main shutoff — or call a plumber. If water is leaking from the supply lines, the wall, or under the sink rather than dripping from the spout, this is the wrong guide.
First, confirm the diagnosis (two free checks)
Check 1 — the drip pattern (2 minutes). Dry the spout and put a dry cup or tissue under it. A drip that falls steadily, hour after hour, with the faucet fully off, is a sealing fault — seat, washer, or cartridge. A drip that runs for a few minutes after you use the faucet and then stops is usually just water draining out of the spout and aerator — normal, and no part will fix it. Only chase a steady drip.
Check 2 — the faucet-type test (10 seconds). Turn the handle fully on and count the rotation. A handle that keeps winding through several full turns is a traditional compression faucet: it has a washer, and this guide applies in full. A handle that turns a quarter or half turn and stops is a cartridge faucet: there is no washer inside to change, so skip straight to the cartridge section below. This one observation explains a great many “changed the washer, still dripping” mysteries — on a cartridge faucet, the washer you changed was never the sealing part.
Check 3 — one faucet or both? A drip from one faucet only is a fault in that faucet. Drips or pressure problems at several faucets at once point to a supply or pressure problem, not to a washer — see “When to stop and call a pro”.
Symptom → cause table
| What you notice | Most likely cause | First check |
|---|---|---|
| Steady drip from the spout, faucet fully off, after a new washer | Scored or corroded valve seat — the washer cannot seal against a rough seat | Remove the stem and run a fingertip over the seat (fix steps 3–4) |
| Steady drip, washer replaced, but the washer was the wrong size or thickness | Wrong washer — too small, too thick, or the wrong profile, so it never sat flat | Compare the old washer with the new one, edge to edge |
| Steady drip, handle stops after a quarter turn | Worn cartridge or O-rings — this is a cartridge faucet, not a washer faucet | Faucet-type test above, then cartridge section |
| Drip only for a few minutes after use, then stops | Residual water in the spout — normal, not a fault | Cup test: steady drip vs draining drip |
| Drip from the handle or the base, not the spout | Stem packing or O-rings — a different seal from the washer | Dry tissue around the handle while the faucet runs |
| Handle stiff, gritty, or hard to turn, plus a drip | Limescale or worn cartridge/stem | Soak-or-replace decision in the cartridge section |
| Drip that returns within days of any fix | Seat damage missed, or the wrong cartridge fitted | Re-inspect the seat under good light before buying again |
You need
- For a compression faucet: the correct washer (take the old one to the shop — size and profile matter), a seat wrench or reseating tool (see the fix steps), and a small flashlight. A magnifying glass helps: seat scoring is often invisible at arm’s length.
- For a cartridge faucet: the replacement cartridge, identified by brand, model, spline count, and length — photograph the old cartridge and its markings before ordering. Plus Allen keys for the handle set screw and an adjustable wrench.
- For either: an adjustable wrench, a cloth to protect the finish, plumber’s grease (silicone, for O-rings and threads — never petroleum grease on rubber parts), and a towel for the small amount of water left in the faucet.
- Optional: white vinegar for a limescale soak on a borderline cartridge (see below).
The fix, step by step — compression faucet (washer type)
- Turn off both shutoff valves under the sink (hot and cold), open the faucet to release pressure, and plug the drain so no small screw disappears down it.
- Remove the handle, then the stem. The handle screw is usually under a decorative cap; the stem then unscrews from the valve body with a wrench. Keep the parts in order — a photo before you start saves a reassembly puzzle.
- Inspect the washer first. Compare it with the one you fitted: same diameter, same thickness, same profile? A washer that is even slightly wrong will drip exactly like a worn one. If it is wrong, fit the correct washer, reassemble, and test — you may be done.
- Inspect the valve seat. Look down into the valve body with the flashlight and run a fingertip lightly over the brass ring the washer presses against. A good seat feels smooth all the way round. A scored seat feels rough, grooved, or pitted — that roughness is your drip. If the seat is cracked, or the valve body itself is corroded or split, stop here: that is a faucet replacement, not a seat repair.
- Dress or replace the seat. If the seat is a separate, removable ring, a seat wrench unscrews it and a matching new seat screws in. If the seat is fixed in the valve body, a reseating tool (a cutter on a T-handle, used gently, a few turns at a time) grinds it smooth again. Work slowly and check often — you are removing a hair’s breadth of brass, and over-cutting ruins the seat. Clean out every metal filing before reassembly; a single filing under the new washer causes a fresh drip.
- Reassemble with the new washer seated flat — no twists, no folds — and a smear of silicone plumber’s grease on the stem threads and O-rings.
- Turn the water back on slowly, check for leaks at the handle and base as well as the spout, then leave the faucet off for 15 minutes with a dry tissue under the spout. Dry tissue = fixed.
The fix, step by step — cartridge faucet
- Turn off both shutoffs, release pressure, plug the drain, exactly as above.
- Remove the handle (Allen key on the set screw, usually under the handle or under a cap), then the retaining nut, and pull the cartridge straight out. Note its orientation — most cartridges only fit one way, and fitting one backwards causes a new set of problems.
- Inspect the cartridge and its O-rings. Cracked plastic, torn O-rings, or heavy limescale crust mean replacement. Light limescale on an otherwise sound cartridge can be soaked in white vinegar for an hour, rinsed, and refitted — this is worth trying once, in hard-water areas, before spending on a part.
- Measure before ordering. Count the splines, measure the length, and note the brand and model from the cartridge or the faucet. Order by those numbers, not by appearance. When the new cartridge arrives, compare it with the old one side by side before fitting it.
- Fit the new cartridge in the same orientation, grease the O-rings lightly with silicone grease, refit the retaining nut and handle, turn the water back on slowly, and run the tissue test as above.
If that didn’t fix it
- Re-check the seat under better light. The most common miss is scoring on the far side of the seat, where a fingertip check is awkward. If in doubt, dress the seat once more, lightly — or replace a removable seat rather than dressing it a second time.
- Re-check the washer size. If you bought the washer by description (“standard washer”) rather than by matching the old one, buy by matching instead.
- Check the stem packing and O-rings. A drip from the handle, or a drip that appears only when the faucet is running, is a stem seal, not the seat — replace the packing or O-rings.
- Check the aerator. A clogged aerator does not cause a drip, but it can make a small drip look bigger and noisier. Clean it while you are there.
When to replace the faucet instead
Repair stops being good economics when the valve body is cracked or corroded, the seat has been dressed more than once and still will not seal, the cartridge is discontinued and no match exists, or the faucet’s finish and internals are both worn out. A decent replacement faucet costs roughly what two or three rounds of wrong parts cost — and it ends the drip for good. Replacing the faucet itself is a straightforward swap on standard connections, but if the supply lines, shutoffs, or connections are corroded, that is a plumber’s job, not a first DIY swap.
Common mistakes
- Changing the washer twice without ever looking at the seat. The seat is the usual culprit on the second attempt — it is also the part most guides skip.
- Buying a cartridge by appearance. Two cartridges can look identical and differ in spline count or length. Measure, then order.
- Over-cutting with a reseating tool. A few gentle turns, checked often, beats one aggressive cut that ruins the seat.
- Forgetting the filings. Metal filings left in the valve body cut the new washer on first use.
- Petroleum grease on rubber parts. It degrades rubber O-rings and washers; silicone plumber’s grease is the right product.
- Fitting a cartridge backwards. Note the orientation before removal, and test hot and cold after refitting.
When to stop and call a pro
Stop and call a plumber if: a shutoff valve is seized, weeping, or missing; the valve body or seat is cracked; supply lines or connections are corroded; water is leaking inside the wall or under the floor; or several faucets drip or lose pressure at once (a supply or pressure problem). None of these are washer jobs, and forcing them turns a drip into a flood.
Cost table (US, typical)
| Item | Typical cost |
|---|---|
| Diagnosis (drip pattern + faucet-type test) | $0 |
| Correct washer | $2–$5 |
| Seat wrench or reseating tool | $8–$20 |
| Replacement valve seat (where removable) | $5–$12 |
| Replacement cartridge | $15–$45 |
| Silicone plumber’s grease | $4–$8 |
| Replacement faucet (when repair stops paying) | $50–$250+ |
| Plumber call-out (seized valves, cracked body, supply work) | Varies by area — get a quote first |
US / UK term box
- Faucet (US) = tap (UK). Same fixture.
- Valve seat (US compression faucets) = the brass seat under a traditional UK tap washer — the same sealing principle, which is why a scored seat defeats a new washer in both countries.
- Cartridge faucet (US) = ceramic-disc / quarter-turn tap (UK). The UK twin of this guide covers ceramic-disc taps in detail; the diagnosis is the same — no washer inside to change.
FAQs
I just replaced the washer and it still drips — did I do something wrong?
Probably not. The most likely explanation is the valve seat underneath the washer, which this guide covers step by step. Check the seat before buying anything else.
How do I know if my faucet is a washer faucet or a cartridge faucet?
Turn the handle fully on and count. Several full turns = compression (washer) faucet. A quarter or half turn that stops = cartridge faucet. That test decides which half of this guide applies.
Can I just keep tightening the handle harder to stop the drip?
No — over-tightening crushes the washer, scores the seat further, and wears the stem. A faucet that only stops dripping when forced shut has a sealing fault, not a tightness problem.
Is a reseating tool worth buying for one faucet?
At $8–$20 it pays for itself against a single plumber visit, and it works on any compression faucet in the house. If the seat is removable, a seat wrench and a new seat are simpler still.
My cartridge faucet drips and the cartridge looks fine — what next?
Check the O-rings first (cheap, and often the real fault), then try the vinegar soak for limescale. If neither helps, replace the cartridge with one matched by spline count and length — “looks the same” is not a match.
Checklist
- [ ] Drip pattern confirmed: steady drip, not post-use draining
- [ ] Faucet type identified: winding handle (washer) or quarter-turn (cartridge)
- [ ] Water off at both under-sink shutoffs, pressure released, drain plugged
- [ ] Washer checked against the old one — correct size and profile
- [ ] Valve seat inspected by fingertip and flashlight — smooth, or dressed/replaced
- [ ] Filings cleaned out before reassembly
- [ ] New washer seated flat, or new cartridge fitted in the correct orientation
- [ ] Water back on slowly; handle, base, and spout checked for leaks
- [ ] Tissue test after 15 minutes: dry = fixed