How do I fix a dripping faucet?

The repair depends entirely on what is inside the faucet, so this step comes before anything else. There are four common designs.

A compression faucet has two separate handles, one for hot and one for cold, and each handle tightens down hard when you shut it off. The drip comes from a worn rubber washer, a damaged valve seat, or a failed O-ring. These are the oldest design and the cheapest to fix.

A cartridge faucet can have one handle or two, and the handle turns smoothly without that hard stop. Inside is a removable cartridge that controls flow. When it wears out, the whole cartridge gets replaced as a unit. Moen is a well-known maker of cartridge faucets, and most brands sell a matching replacement by model number.

A ceramic-disc faucet uses a single handle over a wide cylinder. Two ceramic discs slide against each other to control water. A drip points to worn discs or the rubber seals under the disc cylinder. These last a long time but still fail with age and grit.

A ball faucet has a single handle that moves over a rounded cap, common on older kitchen sinks. Inside, a slotted ball and a set of springs and rubber seats control flow. A repair kit for this type includes the springs, seats, and O-rings.

If you are not sure which one you have, look up the brand and model. Delta, Moen, and Kohler all publish parts diagrams that show the exact internal pieces for each faucet. The model number is often stamped under the spout, on the bottom of the faucet body, or printed on the original paperwork. Knowing the type also tells you where the drip is forming, since a compression faucet drips from the seat while a cartridge faucet drips from a cracked or scaled cartridge sleeve.

A drip looks minor, but the wasted water adds up fast. The U.S. Environmental Protection Agency's WaterSense program reports that a faucet dripping at one drip per second wastes more than 3,000 gallons a year. That is enough water for more than 180 showers, gone one drop at a time.

The cost across the country is large. According to EPA WaterSense, "the average household's leaks can account for nearly 10,000 gallons of water wasted every year." The same program notes that fixing easily corrected household leaks can save homeowners about 10 percent on their water bills.

There is a second reason to act early in Phoenix. A drip on the hot side also wastes the energy used to heat that water, and the U.S. Department of Energy lists water heating among the largest energy uses in a typical home. A slow hot-water drip quietly runs up both the water bill and the gas or electric bill.

Catching a drip early also protects the faucet body. Mineral-laden water running over the same spot day after day etches the valve seat and stains the finish, which can turn a simple part swap into a full replacement. A drip that lands in the sink also leaves hard-water spots and a rust ring on the basin over time, so the fix pays off in the look of the fixture too.

For a sense of scale, EPA WaterSense reports that household leaks nationwide waste close to 1 trillion gallons of water each year. The leaks in a single home are small by comparison, yet they follow the same pattern: a steady, slow loss that runs day and night until the worn part is replaced.

Phoenix tap water is hard. City of Phoenix water quality data puts total hardness in the range of roughly 10 to 17 grains per gallon, which the U.S. Geological Survey classifies as hard to very hard water. That mineral content has a direct effect on the parts inside your faucet.

Calcium and magnesium leave a chalky scale on rubber washers, O-rings, and cartridges. Scale makes rubber stiff and rough, so it no longer seals against the valve seat. The same buildup scratches the smooth surfaces of ceramic discs and cartridge sleeves. The result is that washers and cartridges in Phoenix homes tend to wear out faster than the same parts in a soft-water city.

This is why a Phoenix faucet may start dripping again a year or two after a repair, even when the work was done correctly. The mineral attack never stops. Wiping faucets dry, cleaning aerators, and a whole-house water softener all slow the damage, but hard water remains the main reason these parts have a short life here.

When you take a Phoenix faucet apart, expect to find white crust on the worn part. Soaking metal pieces in white vinegar for 30 to 60 minutes dissolves the scale so the new part seats cleanly. Avoid sharp metal tools on ceramic discs and cartridge sleeves, since a scratch from scraping creates a new leak path. A soft brush and vinegar do the job without marring the sealing surfaces.

Once you know the faucet type and have the matching repair part or cartridge, the work is straightforward. Follow these steps and keep the removed pieces in order so reassembly is simple.

1. 1Shut off the water at the stop valve. Look under the sink for the small stop valves on the hot and cold supply lines and turn them clockwise until they stop. If there is no stop valve, shut off the main water supply to the house. Then open the faucet to drain the line and confirm the water is off.
2. 2Plug the drain. Drop in the stopper or set a rag over the opening so no small screws or springs fall down it.
3. 3Remove the handle. Pry off the decorative cap, back out the screw underneath, and lift the handle free. A handle stuck by scale comes off easier after a few minutes soaking the base in vinegar or with gentle rocking.
4. 4Take out the worn part. For a compression faucet, unscrew the stem and replace the rubber washer and O-ring; check the valve seat and dress or replace it if it is pitted. For a cartridge faucet, pull the retaining clip and slide out the old cartridge. For a ceramic-disc faucet, lift out the disc cylinder and replace the seals. For a ball faucet, install a new springs and seats kit.
5. 5Match and install the new part. Take the old part to the store or order by model number so the replacement fits exactly. Coat O-rings with plumber's grease, then set the new part in place.
6. 6Reassemble and test. Put the handle and trim back on, open the stop valves slowly, and run the faucet. Check for drips at the spout and for leaks under the handle.

If the faucet still drips after a correct part swap, the valve seat itself is likely worn out, which is common in hard-water areas. A seat wrench removes a replaceable seat, but a seat machined into the faucet body usually means the whole faucet should be replaced.

Repairing makes sense when the faucet body is sound and parts are available. Replace the whole faucet instead when the spout or base is corroded, when the brand no longer sells the cartridge or seat, when you have already replaced the worn part and it keeps dripping, or when the finish is badly pitted by years of scale. A faucet more than 15 years old is often cheaper to replace than to chase repeated repairs.

Call a licensed plumber when the stop valve under the sink will not turn or leaks once you touch it, when the supply lines are corroded, when water leaks inside the wall or cabinet, or when removing a scaled-on handle risks cracking the faucet body. These jobs need the right tools and a clean shutoff, and a hidden leak can damage cabinets and drywall.

If the problem is weak flow from one tap rather than a drip, the cause is usually a clogged aerator full of scale, not a worn valve. See our answer on low water flow from one faucet aerator for that fix.

HQ Plumbing & Air serves metro Phoenix and offers 24/7 service for faucet repair, replacement, and the hard-water issues behind most local drips. A quick repair now keeps a few drops from becoming thousands of wasted gallons.