Quick answer
A dripping kitchen faucet spout is a worn cartridge (single-handle faucets) or worn valve seals (two-handle faucets). Both are cheap fixes. Take a photo of your faucet or bring the old cartridge to the hardware store to match — cartridges are brand-specific but generally $10–$25. The whole job takes 20 minutes. Shut off water under the sink first.
Key facts
| Common causes | Worn cartridge (single-handle faucets); Worn O-rings; Worn valve seals (two-handle faucets); Mineral buildup in aerator |
|---|---|
| DIY difficulty | Easy |
| Time to fix | 20 min |
| Parts cost | $10–$25 parts |
| Tools needed | Allen wrench, screwdriver, adjustable wrench |
| When to call a pro | If cartridge replacement doesn't stop the drip |
What's happening
Modern single-handle faucets use a ceramic disc or ball cartridge inside the body to control both hot/cold mixing and flow rate. Over 5–10 years, the ceramic disc's O-rings compress and lose their seal, or grit from the water supply scratches the discs. Water leaks past the seal and drips from the spout. Two-handle faucets use rubber or ceramic seals under each handle — same failure mode, same fix. Aerator drips (from the very end of the spout) are separate — usually a cleanable buildup, not a leak.
Common causes (ranked by frequency)
- Worn cartridge (single-handle faucets) 70% of cases
The most common failure. Replace the cartridge with the manufacturer-specific part (Moen 1225, Delta RP19804, Kohler GP1042930, or match your brand).
- Worn O-rings 15%
Some faucets have replaceable O-rings inside the cartridge cavity. Cheaper fix than full cartridge replacement — a few dollars for a set.
- Worn valve seals (two-handle faucets) 10%
Two-handle faucets have rubber compression seals or ceramic disc valves under each handle. Replace both when you replace one — the other is close to failing.
- Mineral buildup in aerator 5%
Drips at the very end of the spout, especially after using the faucet, are usually aerator buildup. Unscrew the aerator, soak in vinegar overnight, reinstall.
How to diagnose
- Identify the drip location. From the spout end when off = cartridge or valve seals. Only during use, from spout base = O-rings. From the aerator only = mineral buildup.
- Identify your faucet type. Single-handle (one lever for hot/cold/flow) or two-handle (separate hot and cold). This determines the fix path.
- Look up the brand and model. Brand is usually stamped on the base or under the handle. Model number is on the box (if you kept it) or looking up the brand + your faucet's visual match.
- Buy the manufacturer-specific cartridge kit. Universal cartridges rarely fit correctly; get the exact part for your brand.
The fixes
Fix #1 — Replace the cartridge (single-handle faucet) Most common
Manufacturer-specific cartridges come with all seals and washers. Moen 1225, Delta RP19804, Kohler GP1042930 are the three most common. Kits are $15–$25.
Tools
- Allen wrench (usually 1/8 or 3/32 inch)
- Adjustable wrench or channel-locks
- Small flat screwdriver
- Towel
Materials
- Cartridge replacement kit (brand-specific)
- Shut off water at the two valves under the sink (hot and cold). Turn faucet on to release pressure and confirm shutoff.
- Remove the handle. Look for a small hex screw or Phillips screw hidden under a decorative cap on top or on the side. Lift the handle off.
- Remove the retaining ring or bonnet nut (varies by brand). Use adjustable wrench wrapped in tape to protect the finish.
- Pull the old cartridge out. Some pull straight up; some need to be turned first. Note the orientation — the new one goes in the same way.
- Insert the new cartridge. Match the orientation (usually a tab or notch aligns with a corresponding slot in the faucet body).
- Reinstall the retaining ring, handle, and cap in reverse order.
- Turn water back on slowly. Check for leaks around the base.
Fix #2 — Clean the aerator
If drip is only from the aerator screen (very end of spout), it's mineral buildup — 5-minute cleaning.
Tools
- Small pliers (with tape or cloth wrap)
Materials
- White vinegar (1 cup)
- Old toothbrush
- Unscrew the aerator by hand or with pliers (wrapped to avoid scratches). Some faucets have hidden aerators requiring a special tool from the manufacturer.
- Disassemble the aerator — usually a screen, washer, and flow restrictor stacked together.
- Soak all parts in vinegar for 30 minutes (or overnight for heavy buildup).
- Scrub with toothbrush to remove softened deposits.
- Reassemble and reinstall. Hand-tight only — never wrench-tight on aerators.
Prevention
Replace cartridges every 7–10 years as preventive maintenance if you're already going in for another reason. Install a whole-house sediment filter if your water is heavily mineral-laden — it dramatically extends cartridge life. Clean the aerator annually to prevent buildup-related pressure issues.
When to call a pro
When to stop and call a pro
- You've replaced the cartridge with the correct manufacturer part and the drip continues — the faucet body may have cracked or the valve seat is scored.
- The faucet is more than 15 years old and cartridges are no longer available for that model — replacement faucet is the answer.
- You can't identify the brand or model and universal parts don't fit — a plumber can identify and source correctly.
Plumber service call to replace a cartridge: $150–$300 including standard parts. Full faucet replacement labor: $150–$300 on top of faucet cost. A good mid-range replacement faucet is $150–$350.
Cost estimate
Cost estimate
Frequently asked questions
Brand is usually stamped on the base or under the handle. Model number requires looking up the visual match on the manufacturer's site — Moen, Delta, Kohler, and Pfister all have online identification guides.
No. Every major faucet brand uses proprietary cartridges. Buying a 'universal' cartridge is a common mistake — bring the old cartridge to the store for a match, or look up the specific part number for your model.
No — every under-sink location has hot and cold shutoff valves. Close both. If they're stuck (common on older valves), you may need to shut off the main to service the valves too.
That's an O-ring issue at the swivel joint, not a cartridge issue. Different repair — the O-rings inside the spout base need replacing. Same manufacturer-specific approach applies.