⚡ Quick Summary
- Identify your faucet type first — cartridge, ceramic disk, ball, or compression each fail differently and need different fixes
- Drip from spout with handle closed = internal seal or cartridge failure on one or both supply sides
- Drip only after hot water use = possible pressure or thermal expansion issue, not a cartridge problem
- Drip persists after cartridge replacement = debris in the valve, pitted valve seat, or high water pressure
- Even a slow drip wastes over 3,000 gallons per year — this is not a cosmetic problem
The most common mistake in faucet repair is treating all faucets the same. A compression faucet uses a rubber washer that gets pressed against a seat — replacing the washer fixes it. A cartridge faucet uses a sliding cartridge with O-rings. A ceramic disk uses hard plates that can crack from debris. A ball-type faucet has springs, seats, and an O-ringed ball. Replace the washer on a cartridge faucet and you will have fixed nothing.
Step one is always: identify what type of faucet you have. Step two is: determine which supply side (hot, cold, or both) is failing. Everything else follows from those two answers.
The Water Cost of a Dripping Faucet
A faucet dripping once per second wastes approximately 3,000 gallons per year. A faster drip — once every half-second — exceeds 5,000 gallons annually. A steady stream can reach 10,000+ gallons. Beyond cost, continuous dripping accelerates corrosion of faucet components, can cause mold in sink deck seams, and may lead to cabinet damage from moisture migration.
Know Your Faucet Type First
Most Common
Cartridge Faucet
Single or double handle · Moen, Delta, Kohler, Pfister
A removable cartridge controls flow and temperature. O-rings on the cartridge wear and flatten over time, allowing water to bypass the seal. Moen cartridges often fail from O-ring compression. Pfister stem cartridges develop internal bypass leaks. Debris from supply lines can score the cartridge body.
Fix: cartridge replacement. Always flush supply lines before installing the new cartridge to prevent debris from immediately damaging the replacement seals.
Very Durable
Ceramic Disk Faucet
Single lever · American Standard, Grohe, Hansgrohe
Two ceramic discs rotate against each other to control flow. Extremely durable under normal conditions but vulnerable to debris — fine sediment or grit that enters the disk chamber can scratch the ceramic surfaces, preventing a full seal. Restricted handle travel is a key diagnostic signal.
Fix: cleaning the disk chamber and inspecting disc surfaces. Scratched discs require replacement. Never force the handle — it indicates debris obstruction.
Single Handle
Ball-Type Faucet
Single handle rotates and lifts · Delta, Price Pfister older models
A slotted ball rotates over two spring-loaded rubber seats to control flow. Multiple failure points: the seats wear out, springs weaken, O-rings on the ball shaft deteriorate. Because there are several parts working together, ball faucets often require a complete rebuild kit rather than a single part replacement.
Fix: full rebuild kit including springs, seats, O-rings, and ball. Replacing only one component usually results in a second drip within months.
Older Homes
Compression Stem Faucet
Two separate handles · Traditional style, common pre-1980
A threaded stem presses a rubber washer down onto a valve seat to stop flow. The washer hardens, flattens, or cracks over time. The valve seat can become pitted or corroded, preventing a clean seal even with a new washer. This is the only type where “replace the washer” is directly correct advice.
Fix: new rubber washer on the stem (and inspect the valve seat). If the seat is pitted, it needs resurfacing or replacement — a new washer alone will not hold against an irregular seat.
The Hot/Cold Isolation Test
Before opening any faucet, confirm which supply side is failing. This narrows your repair to one side and prevents you from replacing the wrong cartridge or washer.
📌 Hot/Cold Side Isolation — Do This First
- Locate the two angle-stop valves under the sink (or at the fixture supply lines). One feeds hot water, one feeds cold.
- Close the hot-side angle stop completely. Turn the faucet on and observe whether it still drips from the spout.
- If dripping stops with hot closed: the hot-side cartridge, washer, or seat is failing.
- Reopen hot side fully. Close the cold-side angle stop. Observe the drip again.
- If dripping stops with cold closed: the cold-side is failing.
- If dripping continues with either side closed: both sides are failing, or the faucet body itself has a problem.
Symptom-to-Cause Quick Reference
| What You Observe | Most Likely Cause | First Step |
|---|---|---|
| Steady drip from spout, handle fully closed | Worn cartridge, failed O-ring, or hardened washer on one or both sides | Perform hot/cold isolation test to identify the failing side |
| Drip only appears after hot water use, then stops | Thermal expansion or PRV failure — not a cartridge problem | Check household water pressure at a hose bib; target 55–65 PSI |
| Handle stiff or grinding sensation when operating | Debris in cartridge or ceramic disk chamber; scale buildup on stem | Do not force. Remove cartridge and inspect for debris or scoring |
| Drip continues after cartridge was just replaced | Pitted valve seat, debris still in line, or cartridge installed backward | Flush supply lines; inspect valve seat; confirm cartridge orientation |
| Leak around handle base, not from spout | Worn O-rings on the cartridge body or spout swivel ring | Replace O-rings on the cartridge exterior; check spout base ring |
| Multiple faucets dripping simultaneously | High water pressure system-wide (above 80 PSI) | Test pressure at hose bib; PRV adjustment or replacement may be needed |
| Faucet drips even with angle stops fully closed | Angle stop failure or faucet body crack — not a cartridge issue | Call a plumber; this is a supply-line or fixture-body problem |
The Most Common DIY Failure: Skipping the Supply Line Flush
When you install a new cartridge without first flushing the supply lines, debris from the lines flows directly into the new cartridge and damages the seals within days. Before installing any new cartridge, remove it from the valve body, place a rag over the opening, and briefly open the angle stop to flush debris out of the supply line. Then install the cartridge. This single step prevents the most common cause of “the new cartridge is already dripping.”
J.G.
From the Expert
"The call I hate the most is the callback after a DIY cartridge replacement. Homeowner replaced the cartridge, still drips, now frustrated. Almost always one of three things: they did not flush the supply line first and debris damaged the new seals immediately; they put the cartridge in backward — easy to do on Moen and American Standard — which causes temperature reversal and incomplete shutoff; or the valve seat is pitted and no cartridge is going to seal against it. The valve seat is the part nobody thinks about. You can put in a brand new cartridge but if the seat it sits on is corroded and rough, it will never seal properly. On compression faucets especially, seat inspection is step one."
— J.G., Licensed Plumber · 50+ Years Commercial & Residential Service Work
How Serious Is It?
Minor — Occasional Drip
Faucet functions normally otherwise. Still wastes thousands of gallons per year. Address within weeks.
Moderate — Consistent Drip
Handle stiff or hard to close fully. Component wear accelerating. Repair soon before full failure.
Major — Continuous Flow
Rapid drip or small stream. Visible leakage around handle or base. Repair immediately to prevent cabinet damage.
Critical — Cannot Shut Off
Faucet will not close. Angle stop is failing. Shut water at the main and call a plumber.
What You Can Safely Attempt vs. When to Call
✓ Reasonable DIY (with research)
- Clean aerator and check for sediment restricting flow
- Replace a cartridge on a single-handle faucet (after identifying the exact model)
- Replace a rubber washer on a compression stem faucet
- Replace O-rings on a cartridge or swivel spout body
- Use hot/cold isolation test to identify the failing supply side
- Tighten a loose packing nut (carefully — do not overtighten)
✗ Call a Licensed Plumber
- Faucet drips after two cartridge replacements — valve seat likely needs resurfacing
- Angle stops will not close or are leaking — do not attempt to force them
- Multiple faucets dripping — system pressure issue requiring PRV adjustment
- Faucet body appears cracked or leaking internally
- Valve seat is corroded and non-removable — requires specialized tooling
- Faucet will not shut off at all — shut main and call immediately
Frequently Asked Questions
How do I know what type of faucet I have?▾
Start with how many handles it has and how they move. Two separate handles that rotate = likely compression or cartridge. A single handle that moves in multiple directions (up/down for flow, side to side for temperature) = ball-type or cartridge. A single lever that moves primarily side to side = usually ceramic disk. If you cannot tell from the outside, look up the model number — usually on the faucet body near the base or on original paperwork. Manufacturer websites provide cartridge identification by model. Moen, Delta, Kohler, and American Standard all have online resources for this.
I replaced the cartridge but it's still dripping. What did I miss?▾
Three most likely causes: the supply line was not flushed before installation, allowing debris to damage the new cartridge seals immediately; the cartridge was installed with incorrect orientation (common on Moen cartridges, which have an alignment tab that must engage correctly); or the valve seat in the faucet body is pitted or corroded, and no cartridge will seal against an irregular seat surface. If the drip continues after a correctly installed, properly flushed cartridge, have a plumber inspect and resurface or replace the valve seat.
My faucet only drips at night. Why?▾
This almost always indicates a pressure issue, not a worn cartridge. Municipal water pressure typically rises at night when neighborhood demand drops. Higher pressure during low-demand hours overwhelms a slightly worn cartridge that holds adequately during the day. It can also indicate thermal expansion — if the water heater is heating overnight and the system lacks a thermal expansion tank, pressure spikes after the heating cycle can push water past a partially worn seal. Test your household water pressure with an inexpensive gauge at a hose bib — anything consistently above 80 PSI warrants PRV inspection.
Is a dripping faucet something I should fix myself or call a plumber for?▾
It depends on your comfort level and the faucet type. Cartridge replacement on common faucet brands (Moen, Delta, Kohler) is a legitimate DIY project if you can identify the exact model number, source the correct cartridge, and follow the supply-line flush procedure. Compression washer replacement is even more accessible. Where DIY tends to fail: ball-type faucets with multiple parts to reassemble correctly, ceramic disk faucets where the chamber must be cleaned without scratching the discs, and any situation where the valve seat needs resurfacing. A plumber visit for a dripping faucet is typically a straightforward and affordable service call — often less than the cost of buying multiple wrong parts over several attempts.
Can high water pressure cause a faucet to drip?▾
Yes — and it is one of the most commonly overlooked causes of recurring drips. When household pressure consistently exceeds 80 PSI, it places continuous stress on cartridge seals and O-rings, accelerating wear and eventually pushing water past seals that would otherwise hold at normal pressure. The diagnostic sign is multiple faucets dripping simultaneously, or a drip that develops shortly after a new cartridge is installed. Test pressure at a hose bib with an inexpensive gauge. If it is above 80 PSI, a PRV (pressure-reducing valve) adjustment or replacement is the root fix — not repeated cartridge replacement.
Key Takeaways
- Identify your faucet type before buying any parts — cartridge, ceramic disk, ball, and compression each require completely different repairs.
- Run the hot/cold isolation test to identify which supply side is failing before opening the faucet.
- Always flush supply lines before installing a new cartridge — debris in the line will immediately damage new seals.
- If a new cartridge still drips, the valve seat is likely pitted. No cartridge seals against a corroded seat.
- Multiple faucets dripping simultaneously or drips that appear only at night usually indicate a pressure problem, not worn cartridges.