A slow drip today is a bigger repair tomorrow, most fixes take under an hour.
A dripping faucet or tap almost always means a worn internal seal, a washer and valve seat on an older two-handle faucet, or a cartridge and its O-rings on a modern single-handle faucet. Shut off the water supply, identify which type you have, replace the worn part, and reassemble. Most repairs take under an hour and cost far less than a full faucet replacement.
A faucet that drips even when fully closed means an internal seal has worn out and water is slipping past it, not that the faucet is simply old or "worn out" as a whole. On older two-handle faucets, that's usually a washer pressing against a valve seat. On modern single-handle faucets, it's usually a cartridge and the O-rings around it. Knowing which type you have, and where exactly the water is coming from, narrows the fix to one inexpensive part almost every time.
This guide covers the real causes behind a drip, the distinction between dripping when off and dripping while running (they point to different parts), how to fix each type, why a faucet sometimes keeps dripping even after a cartridge swap, and when a repair stops making sense and a full replacement is the better call.
- A drip from the spout, on or off, points to the shutoff seal: a washer and valve seat, or a cartridge.
- Water at the base of the spout or under the handle while running points to a worn O-ring, a different fix.
- Mineral scale on the valve seat can stop even a healthy washer or cartridge from sealing fully.
- If a drip continues after a cartridge swap, check the O-ring, the seating, and the cartridge model match before assuming the part is defective.
- Repair when the faucet body is sound and parts are available; replace when the body is corroded or the faucet has failed repeatedly.
Common causes
Every drip comes down to the same basic mechanism: a part designed to seal tightly, whether that's a rubber washer pressed against a metal seat, or a modern cartridge's internal seals, has worn, cracked, or been fouled by mineral buildup, so it no longer closes the water path completely. The specific part depends on the faucet type.
| Faucet type | Shutoff part | Typical failure |
|---|---|---|
| Older two-handle (compression) | Rubber washer + valve seat | Washer hardens, cracks, or wears unevenly; seat corrodes or pits |
| Modern single-handle | Cartridge | Internal seals wear or clog with sediment |
| Ball-type or ceramic-disc | Ball with springs/seats, or ceramic discs | Seats wear or discs no longer seal flush |
Mineral scale is worth calling out separately, since it can undermine an otherwise healthy part. Even a new washer or cartridge can't form a tight seal against a valve seat crusted with hard water deposits, and in areas with harder water, scale buildup is often the real reason a "fixed" faucet starts dripping again within a year.
A Note on Whistling Taps (UK)
A whistling or squealing sound when a tap runs usually traces back to the same worn parts as a drip, a worn washer or cartridge vibrating as water passes through it, or a partially closed valve restricting flow. It's common on older compression taps in the UK, and replacing the washer or cartridge often resolves both the noise and the drip at the same time.
Dripping when off vs when running
Where the water appears, and when, is the fastest way to identify the actual part at fault, and it's the distinction most repair attempts skip.
Locate the Drip Before Buying Parts
- Drip from the spout tip, faucet fully off: the shutoff seal has failed, washer and valve seat, or cartridge
- Water pooling at the base of the spout or seeping under the handle while running: a worn O-ring, not the shutoff part
- Drip that only appears at night or when no one's using water: often the same worn washer or seat, made worse by house water pressure rising overnight
- Water pooling under the sink in the cabinet: a loose supply line or shutoff valve connection, not the faucet itself
This matters because the two problems call for different repairs. Replacing a cartridge when the actual leak is an O-ring at the spout base won't stop anything, and vice versa. A few minutes watching exactly where the water appears saves a wasted trip for the wrong part.
Approximate reference only. Exact layout varies by model, check your faucet's own manual before ordering parts.
Know Your Faucet Before You Start
Where the seal actually sits
The cartridge and its surrounding O-ring seals sit just below the handle, held in place by a retainer nut. The shutoff seal, the part responsible for stopping water when the handle is off, is what you're replacing for a spout drip. The O-rings around it are a separate part, worth inspecting and replacing at the same time even if they look intact.
How to fix: washer, cartridge, O-ring
Before touching any faucet, shut off the water at the shutoff valves under the sink, then open the faucet to release remaining pressure in the lines. Keep a small bowl or rag handy, there's usually a small amount of residual water in the line even after the supply is off.
Tools You'll Need
- Adjustable wrench or basin wrench
- Flathead and Phillips screwdrivers, plus an Allen key for some handle set screws
- Plumber's tape and plumber's grease
- Replacement washer, cartridge, or O-ring kit matched to your faucet's exact brand and model
- A small bowl or rag for residual water
Replacing a washer (older two-handle faucets)
Remove the decorative cap on the handle, unscrew the handle itself, and remove the stem assembly to expose the washer at the bottom, held on by a small screw. Replace it with an exact match in size and shape, an incorrect washer will drip again quickly, and inspect the valve seat underneath for pitting or corrosion while it's accessible. A rough, uneven seat will keep a new washer from sealing no matter how well the washer itself fits.
Replacing a cartridge (modern single-handle faucets)
Remove the handle, then the retainer nut or clip holding the cartridge in place, and pull the cartridge straight out, a cartridge puller tool helps if it's stuck from mineral buildup. Confirm the replacement is an exact match for the faucet's brand and model before installing, cartridges are not universal even when they look similar. Lubricate the new cartridge's O-rings with plumber's grease before seating it, this protects the seal during installation and helps the faucet operate smoothly afterward.
Replacing an O-ring
If the leak is at the spout base or under the handle while the faucet runs, the O-ring around the cartridge or spout body is the more likely culprit rather than the cartridge itself. O-rings are inexpensive and usually sold in multi-packs or included in a faucet repair kit alongside the cartridge, replacing them at the same time as a cartridge swap is cheap insurance against a second repair.
Dripping after replacing a cartridge
A drip that continues after a cartridge replacement is frustrating, but it almost always traces back to one of a few specific, fixable causes rather than a defective part.
Why the New Cartridge Isn't Fixing It
- Wrong cartridge model: even a fraction of a millimeter off in fit compromises the seal, confirm the exact manufacturer and model before buying
- Cartridge not fully seated: a cartridge that isn't pushed all the way in or aligned correctly won't seal properly, even if everything looks assembled
- O-ring not replaced: a worn O-ring left in place, or a new one installed without lubrication, can leak independently of a perfectly good cartridge
- Valve seat still worn: if the underlying seat is corroded or pitted, a new cartridge sits against damaged brass and still can't seal fully
- Debris in the line: a bit of sediment or scale can lodge against the new cartridge right after installation, flushing the lines before reassembly helps prevent this
The most reliable fix, when a repeat leak shows up, is replacing all the small parts in the repair kit together rather than just the cartridge on its own, since an old, hardened O-ring or a pitted seat will undermine even a brand-new cartridge.
When to repair vs replace
Most dripping faucets are worth repairing. A washer, cartridge, or O-ring swap is inexpensive, the parts are widely available for common brands, and the job itself is usually under an hour for anyone comfortable with basic hand tools.
Replacement makes more sense once the faucet body itself, not just the internal parts, shows real wear: corrosion or pitting in the brass, a finish that's failed structurally rather than aged naturally, or a faucet that's already had more than one repair and keeps developing new leaks in different places. At that point, a repeated cycle of small repairs usually costs more in time and parts than a single solid faucet built to last. This is one advantage of solid unlacquered brass construction: brass bathroom faucets and brass kitchen faucets built with straightforward internal parts, washers, O-rings, and cartridges, rather than proprietary electronics, stay serviceable with ordinary hand tools for the long run rather than becoming obsolete the moment one part wears out.
Cost is worth weighing into that decision too. DIY parts for a typical repair run roughly $5 to $60, a washer or O-ring kit at the low end, a brand-specific cartridge at the higher end. Hiring a plumber typically runs $100 to $300 total for a standard repair, factoring in a service call fee plus labor billed at $45 to $200 an hour. I'm not fully confident these figures hold everywhere, they're US averages pulled from several cost-guide sources and vary by region and faucet brand, so treat them as a general planning range rather than a quote.
According to the EPA's WaterSense Fix a Leak Week program, household leaks, including dripping faucets, waste nearly 1 trillion gallons of water nationwide each year, and the average household's leaks account for more than 9,300 gallons wasted annually. A drip that seems minor adds up fast, which is part of why fixing it promptly, rather than living with it, is usually the better call even before the repair itself gets any harder.
If you're weighing a repair against a full swap, the complete guide to replacing a bathroom faucet covers the full installation process, and the drains and hardware collection has the supply lines, p-traps, and small parts that often need replacing alongside a new faucet.
Frequently Asked Questions
Why is my faucet dripping when off?
A faucet that drips after it's fully turned off almost always means the internal shutoff seal has worn out, a washer and valve seat on an older two-handle faucet, or a cartridge on a modern single-handle faucet. That seal is what stops water reaching the spout at all, so once it wears, gaps, or gets fouled with mineral scale, a small amount keeps passing through even with the handle closed.
How do I fix a dripping tap?
Turn off the water supply at the shutoff valves under the sink, remove the handle, and identify the faucet type. On an older two-handle compression faucet, replace the washer and inspect the valve seat. On a modern single-handle faucet, replace the cartridge and its O-rings together. Reassemble, turn the water back on slowly, and check for drips before considering the job done.
Why is my faucet still dripping after I replaced the cartridge?
The most common reasons are a cartridge that doesn't exactly match the faucet model, an O-ring that wasn't replaced alongside it, the cartridge not fully seated during installation, or a valve seat that's still worn or corroded underneath. Replacing all the small parts in the repair kit at once, not just the cartridge, avoids most repeat leaks.
Should I repair or replace a dripping faucet?
Repair if the faucet is otherwise in good condition and parts are available, a washer, cartridge, or O-ring swap is usually inexpensive and quick. Replace if the faucet body itself is corroded or pitted, if it's an older model where matching parts are hard to source, or if it's already had multiple repairs and keeps failing in new places.
Why does my tap whistle?
A whistling or squealing tap is usually caused by the same worn parts that cause dripping, a worn washer or cartridge vibrating as water passes through it, or a partially closed valve or mineral buildup restricting flow. It's common in the UK on older compression taps and often clears up once the washer or cartridge is replaced.
If a repair keeps coming back, or the faucet's finish and body have run their course, it may be time for a new one. Browse the Insideast faucet collection, solid unlacquered brass and copper, handmade in Marrakech, with internal parts that stay standard and serviceable for the long run.
