That steady drip from the bathroom sink may seem minor, but it can waste water, stain a fixture, and signal a worn part that will not improve on its own. Understanding why faucets leak and how to repair them helps you act before a simple repair becomes a damaged cabinet, corroded valve, or expensive service call.
Most faucet leaks come down to a small number of moving parts. The challenge is identifying where the water is escaping before taking anything apart. A faucet that drips from the spout has a different problem than one leaking around the handle or beneath the sink.
Start by Finding the Exact Leak Location
Dry the faucet completely, then run the water and watch it for a minute. Check the spout, the base of the faucet, each handle, the spray hose if you have one, and the cabinet below. Water often travels along the faucet body or supply lines, so the place where you see a drop is not always the place where the leak began.
A drip from the spout after the faucet is turned off usually means an internal sealing part is worn. Water around the handle typically points to an O-ring, packing nut, cartridge, or stem seal. A leak under the sink may come from a loose supply connection, a failed shutoff valve, or a cracked hose rather than the faucet itself.
Before starting a repair, place a dry paper towel under each connection. It makes slow leaks much easier to pinpoint. If the water appears only when the faucet is running, you may be dealing with a spray hose, faucet body, or drain issue. If it continues while the faucet is off, focus first on the valve and supply side.
Disclosure: As an Amazon Associate, I may earn from qualifying purchases.
Why Faucets Leak and How to Repair Them
The right repair depends on the faucet design. There are four common types: compression, cartridge, ball, and ceramic-disc faucets. You do not need to be a plumbing professional to repair many of them, but you do need the correct replacement parts.
Worn washers in compression faucets
Compression faucets are common in older homes. They have separate hot and cold handles that must be tightened to stop the water. Inside each handle is a stem with a rubber washer at the bottom. Every time you turn the handle, that washer presses against a valve seat to block water flow.
Over time, the washer hardens, cracks, or becomes misshapen. The result is the familiar drip from the spout. A rough or corroded valve seat can also damage a new washer quickly, so inspect it while the faucet is apart.
To repair it, shut off the hot and cold water valves below the sink. Open the faucet to relieve pressure, cover the drain so small screws cannot fall into it, and remove the handle. Unscrew the stem, replace the washer and screw at its base, then inspect the valve seat. Reassemble the faucet, turn the supply valves back on slowly, and test for drips.
If the seat is pitted or badly corroded, replacing only the washer may provide a short-term fix. The seat may need to be resurfaced or replaced.
Failed cartridge in single-handle faucets
Many modern kitchen and bathroom faucets use a cartridge to control water flow and temperature. The cartridge contains seals and internal channels that wear with normal use, especially in areas with hard water or sediment in the supply lines.
A failing cartridge can cause a dripping spout, water leaking from the handle, difficulty controlling temperature, or a handle that feels stiff. In most cases, replacing the entire cartridge is more reliable than trying to replace individual seals.
After shutting off the water, remove the decorative cap on the handle, loosen the set screw, and lift off the handle. Depending on the model, you may need to remove a retaining clip or threaded nut before pulling out the cartridge. Take the old cartridge with you when buying a replacement. Cartridges can look nearly identical while having different stem shapes, ports, or alignment tabs.
Install the new cartridge in the same orientation as the old one. Forcing it into place can damage the faucet body or prevent proper operation. Apply a small amount of plumber’s silicone grease to rubber O-rings if recommended by the manufacturer. Do not use petroleum-based grease, which can damage rubber components.
Worn O-rings and seals around the handle
When water leaks around the base of a handle, the faucet may still shut off properly at the spout. That usually means the internal seal around the stem or cartridge is worn.
O-rings are inexpensive rubber rings that create a watertight seal between moving parts. They can flatten, crack, or tear over time. Replacing them often stops a handle leak, but it is smart to inspect the cartridge or stem at the same time. A scored stem can ruin a new O-ring quickly.
Use a small pick or flat screwdriver carefully to remove the old ring. Avoid scratching the metal surface where the new O-ring sits. Match the replacement by size and thickness, lubricate it lightly with silicone grease, and reassemble the faucet without over tightening the retaining nut.
Mineral buildup in ceramic-disc faucets
Ceramic-disc faucets are durable and generally reliable, but they can leak when sediment or mineral deposits interfere with the ceramic discs or damage their rubber inlet seals. This is common where water contains sand, scale, or other debris.
The repair usually involves removing the handle and disc cylinder, cleaning the inlet openings, and replacing worn seals. If the ceramic discs are chipped or scratched, replace the complete disc cartridge. Do not scrape the discs with metal tools. Their smooth surfaces are what allow them to seal properly.
If sediment is a recurring problem, consider the condition of your home’s water supply and shutoff valves. Repeated cartridge failures may be a sign that debris is entering the fixture from aging pipes or a water heater rather than a problem with the faucet alone.
Tools That Make the Repair Easier
For most faucet repairs, you will need an adjustable wrench, Phillips and flat-head screwdrivers, Allen keys, a small towel, and silicone plumber’s grease. A basin wrench can help with connections under the sink, although it is not always needed for internal faucet repairs.
Keep a phone nearby to take photos as you remove parts. This simple habit prevents confusion during reassembly, especially with retaining clips, spacers, and cartridge orientation. It also helps you identify the correct replacement part at a hardware store.
Avoid using excessive force. Faucet handles, decorative caps, and retaining nuts can be damaged easily, particularly on older fixtures. If a part is seized by corrosion, use a penetrating lubricant and give it time to work rather than twisting harder.
Do Not Forget the Shutoff Valves
A repair can go wrong quickly if the shutoff valves under the sink do not close fully. Test them before disassembling the faucet. Turn each valve clockwise, then open the faucet to confirm the water has stopped.
If water continues to run, stop and address the shutoff valve first. In some homes, you may need to shut off water at the main supply. Never rely on the faucet handle alone to hold back water while you remove internal parts.
When turning the water back on, open the shutoff valves slowly. Then inspect all connections and the faucet base for several minutes. A repair that looks dry immediately can reveal a small leak once pressure is fully restored.
When a Faucet Repair Is No Longer a DIY Job
A homeowner can usually replace a washer, O-ring, or cartridge with patience and the correct parts. Call a professional when the faucet body is cracked, the valve seat is severely damaged, supply pipes are corroded, or the shutoff valve fails to close. Those conditions can turn a manageable faucet repair into a water-damage problem.
You should also get help if the leak is inside a wall, beneath a slab, or connected to a commercial fixture with backflow or code requirements. For property managers and owners in Sint Maarten, Ainstheplumber can help diagnose the source, repair the fixture, and check for hidden damage before it spreads.
A faucet should turn on smoothly, shut off cleanly, and leave the sink cabinet dry. If yours does not, start with the leak location, use the right replacement part, and take your time. A careful repair today protects more than water – it protects the space around it.
Recommended Tools & Plumbing Guide
As a plumber with over 20 years of experience, I’ve seen how the right tools can make the difference between a quick fix and major damage. I’ve put together a list of trusted plumbing tools and leak detection products that homeowners can use to catch problems early and protect their homes.
👉 Browse my recommended tools and products here
📘 Get my practical plumbing guide:
https://www.amazon.com/dp/B0F9ZZJCJG
— Ainsworth Dickenson
Your Go-To Plumbing Expert