A dripping faucet wastes between 4 and 8 gallons of water per day at a typical leak rate, which adds up to 1500 to 3000 gallons per year and a measurable bump on the water bill. The fix is usually 5 to 30 dollars in parts and 30 minutes of work, but only if you correctly identify what type of faucet you have. The four major design families (compression, cartridge, ball, ceramic disc) fail in different ways and use completely different repair parts. Buying the wrong kit, or treating a worn seat like a worn washer, is the most common reason a DIY repair fails on the first try. Here is how to diagnose what is leaking and from where, before you spend money at the hardware store.
The four faucet types
Compression
The oldest design, found in homes built before the 1970s and in budget builder-grade fixtures still sold today. Two separate handles, one for hot and one for cold. Inside each handle is a brass stem that screws down against a rubber washer and a brass seat. Closing the handle compresses the washer onto the seat, stopping the flow.
Failure mode: the rubber washer hardens, cracks, or deforms over time. The brass seat can also pit or corrode. A drip from the spout means one of those parts is worn. Identify which side by closing only the hot handle (the leak stops or persists) and repeating with the cold.
Parts cost: a washer kit is 3 to 8 dollars. A seat resurfacing tool (or a replacement seat) is 5 to 15 dollars more.
Cartridge
Most single-handle faucets from the mid-1970s onward. A sealed plastic or brass cartridge sits inside the body, and the handle lifts or rotates the cartridge to control flow and temperature. No rubber washers in the traditional sense.
Failure mode: the cartridge itself wears (O-rings on the cartridge body, internal seals between hot and cold) or scales up in hard water. The fix is to pull the whole cartridge and replace it.
Parts cost: a Moen 1225 cartridge runs 18 to 35 dollars. A Delta RP19804 cartridge is 25 to 40 dollars. Off-brand cartridges are often 8 to 15 dollars and have higher failure rates.
Ball
Single-handle faucet with a hollow metal ball inside the body, drilled with passages that align with hot and cold inlets as the handle moves. Common in Delta and some Peerless products from the 1980s through 2000s.
Failure mode: the springs and rubber seats under the ball compress and wear. Less commonly, the ball itself scores.
Parts cost: a Delta ball faucet repair kit is 12 to 20 dollars and includes the seats, springs, and cam.
Ceramic disc
Two polished ceramic discs slide against each other to control flow. Found in higher-end faucets from the 2000s onward and in essentially all premium kitchen faucets today.
Failure mode: extremely durable. When ceramic disc faucets do leak, the cause is almost always a worn rubber seal or O-ring around the cartridge, not the discs themselves.
Parts cost: a ceramic disc cartridge ranges 30 to 75 dollars depending on brand.
Where the leak is telling you what is wrong
| Leak location | Likely cause |
|---|---|
| Spout drips when off | Worn washer (compression), worn cartridge seal (cartridge/ball/disc) |
| Water around the base when on | O-ring around the spout body |
| Water under the sink, supply line | Compression nut, ferrule, or supply line itself |
| Water under the sink, faucet base | Mounting gasket or putty under the faucet |
| Handle weeps when on | Packing nut on a compression faucet, or O-ring on a cartridge stem |
| Sprayer drips | Diverter valve in the body |
Read the leak first, then disassemble. Tearing apart a single-handle faucet looking for a worn O-ring at the base when the real leak is a worn cartridge wastes an hour.
The repair sequence
For any faucet repair the sequence is the same:
- Turn off the angle stops under the sink (the small valves on the supply lines). Open the faucet to verify the water is off.
- Plug the drain so small parts cannot escape.
- Lay a towel in the basin.
- Photograph the faucet from multiple angles before disassembly.
- Remove the handle. Most have a decorative cap covering a single screw. Pry the cap with a small flathead.
- Remove the bonnet nut, retaining clip, or cartridge nut depending on type. A pair of channel-lock pliers wrapped in tape protects the finish.
- Pull the cartridge or stem straight up. If it sticks, a cartridge puller (15 to 25 dollars) helps.
- Inspect the removed part. Look for cracked rubber, deformed O-rings, scale buildup, or visible scoring.
- Take the part to the hardware store or order online. Brand and model matter, take the photograph too.
- Install the new part, reassemble in reverse order, restore water, test.
Common mistakes to avoid
- Over-tightening on reassembly. Modern faucet bodies are mostly zinc alloy or thin brass and will crack under excess torque. Snug is right.
- Using teflon tape on cartridge threads. Cartridge threads are not pipe threads and the tape will compress unevenly.
- Replacing only one O-ring when the kit includes three. The other two are about to fail, do them all.
- Forgetting to lubricate the new cartridge. A small dab of plumber’s silicone grease on the O-rings extends life significantly.
- Reusing a deformed retaining clip. The clip is the part that holds the cartridge in against water pressure. A worn clip can blow the cartridge out under pressure.
When the leak is not the faucet
Water under the sink can come from places that look like the faucet but are not:
- A failed angle stop where the supply line connects to the wall. The packing nut behind the handle weeps. Tightening the packing nut sometimes helps, replacing the valve is the right fix.
- A pinhole in the supply line itself. Braided stainless lines last 8 to 12 years before the rubber liner inside can fail. Cheap chrome flex lines fail faster.
- A drain leak that runs back along the underside of the sink and accumulates near the faucet base.
- A bad putty or gasket seal between the sink and the countertop, leaking down the threads.
Diagnose by drying everything completely, running the faucet for two minutes, and watching where water reappears first.
When to call a licensed plumber
DIY scope covers cartridge and washer swaps, O-ring replacements, and angle stop replacements where the existing valve will turn off. What is outside that scope:
- Angle stops that will not turn off, which means the leak cannot be stopped without killing the main shutoff and working on a live line
- Copper supply lines that need to be cut and refitted because the angle stop is frozen
- Leaks at the wall behind the faucet that suggest a leak in the in-wall plumbing
- Galvanized supply pipes (older homes) where any disassembly risks breaking the corroded threads
- Any work that requires a permit, which is generally the case for any rough plumbing change
A licensed plumber’s service call (typically 125 to 250 dollars for the first hour in 2026, depending on region) is worth it when the alternative is a flooded cabinet or water damage. For related coverage on plumbing-adjacent projects, see our methodology page.
Frequently asked questions
How can I tell if my faucet is a cartridge or compression type?+
The handle is the giveaway. A compression faucet has two separate handles (hot and cold) that get noticeably stiffer as you tighten them all the way off, because you are physically compressing a rubber washer onto a seat. A cartridge faucet has a single handle (or two handles that turn smoothly through their full range with no resistance gradient) and operates by sliding or rotating a sealed cartridge.
Why does my faucet drip more at night than during the day?+
Static water pressure in the supply line is highest at night when neighborhood demand is lowest. A worn seat or cartridge that just barely holds back daytime pressure will weep at night. If your home's pressure regulator is failing or absent, nighttime pressure can spike to 90 to 100 psi, well above the 60 to 70 psi most fixtures are rated for. A simple test gauge on the hose bib (10 dollars) confirms the issue.
How long does a faucet cartridge typically last?+
Most plastic-bodied cartridges last 8 to 15 years before the seals wear or scale builds up. Ceramic disc cartridges last 15 to 25 years and sometimes outlive the faucet body itself. Brass-bodied cartridges are in the middle. Hard water shortens all of those numbers by 30 to 50 percent because the mineral scale abrades the seals as the cartridge moves.
Is it worth repairing an old faucet or should I just replace it?+
If the faucet is under 10 years old and is a recognized brand (Moen, Delta, Kohler, Pfister, American Standard), repair is almost always cheaper than replacement. A cartridge or O-ring kit runs 8 to 35 dollars versus 75 to 300 for a comparable new faucet plus installation. For off-brand or builder-grade faucets where parts are hard to find, replacement often makes more sense after the second leak.
Why is there water under my sink even though the faucet is not dripping at the spout?+
The leak is in the supply lines, the angle stops, or the faucet base. Run your finger along each fitting under the sink and feel for moisture. Common culprits are the compression nuts on the supply lines (over-tightened by a previous installer until the ferrule cracked), the rubber gasket under the faucet base, or the angle stop valve packing. Catching it early prevents cabinet damage.
