Staring at a steady drip... drip... drip... in the middle of the night is enough to drive anyone insane. Honestly, it’s not just the sound. It’s the visual of your hard-earned money literally sliding down the drain. You’ve probably tried tightening the handle until your knuckles turned white, only to realize the leak isn't stopping. It might even be getting worse. Learning how to fix a bathroom faucet isn't just about saving the thirty bucks a month on your water bill; it’s about reclaiming your sanity and realizing that you don't actually need to pay a plumber $200 for a thirty-minute job.
Most people panic because they see chrome and think "complex machinery." It's not. It’s basically just a series of seals and valves holding back high-pressure water. If you can use a screwdriver and a wrench without hurting yourself, you can do this.
Why Your Faucet Is Leaking in the First Place
Before you go ripping things apart, you need to know what you’re looking at. Water is surprisingly abrasive. Over years, the minerals in your city water—or the sediment from your well—act like sandpaper on the internal rubber components. Eventually, those seals fail.
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There are four main types of faucets you’ll run into in a standard bathroom: compression, ball, cartridge, and ceramic disk. Compression faucets are the old-school ones. They have two handles, and you feel them get "tight" as you turn the water off. The other three are "washerless." If you have a single-handle faucet that you lift or rotate, it’s almost certainly a cartridge or a ball valve.
Why does this matter? Because the fix for a compression faucet is a $0.50 rubber washer, while a cartridge faucet usually requires a $20 replacement part. Don't buy parts yet. Seriously. Wait until you see the "guts" of the thing, or you'll end up making three trips to Home Depot.
The Tools You Actually Need
Forget those massive pipe wrenches you see in cartoons. You aren't working on a steam engine. You need a small-ish adjustable wrench (an 8-inch Crescent wrench is the gold standard), a set of Allen keys (hex keys), a Phillips head screwdriver, and maybe some needle-nose pliers.
One thing most "pro" guides miss: vinegar. If your faucet is more than five years old, it’s going to be covered in calcium deposits. You’ll want to soak the metal parts in white vinegar to actually see what you’re doing. Also, get some plumbers’ grease. It’s a silicone-based lubricant that makes everything slide together smoothly and prevents the new seals from cracking.
Step One: The Most Important Rule of Plumbing
Turn off the water. Just do it.
I’ve seen people try to swap a cartridge with the pressure still on. It results in a literal geyser hitting the bathroom ceiling. Look under the sink. You should see two silver oval-shaped handles. Turn them clockwise until they stop. If they’re stuck—which happens a lot in older homes—don't force them with a wrench or you might snap the stem. If they won't budge, you’ll have to go to the main water shut-off for the whole house.
Once the water is off, open the faucet handles. This releases the remaining pressure. It also lets the water sitting in the pipes drain out so it doesn't spill into your cabinet.
Accessing the Inner Workings
This is where people get tripped up. Where are the screws? Manufacturers love hiding them. Look for a tiny decorative cap—it might say "H" or "C," or it might just be a silver plug. Pop that off with a thin flathead screwdriver. Underneath, you’ll find the screw that holds the handle on.
For single-handle faucets, look for a tiny hole near the base of the handle. There’s a grub screw (set screw) in there. You’ll need an Allen key to loosen it. You don't usually need to take the screw all the way out; just loosen it enough to wiggle the handle off.
How to Fix a Bathroom Faucet: The Cartridge Swap
The cartridge is the "brain" of most modern faucets. If your faucet is a Moen, Delta, or Kohler, it’s likely a cartridge system. Once the handle is off, you’ll see a brass or plastic piece sticking up.
- Remove the bonnet nut. This is the large metal ring holding the cartridge in place. Use your adjustable wrench. If it’s stuck, wrap a rag around it so you don't scratch the finish.
- Pull the cartridge straight up. Sometimes they are stubborn. You might need pliers. Some Moen faucets actually come with a little white plastic tool to help you twist and loosen the cartridge before pulling.
- Check the "O-rings." Sometimes the cartridge is fine, but the rubber rings on the outside are nicked. If the cartridge looks cracked or has heavy mineral buildup, just replace the whole thing.
Pro Tip: Take the old cartridge to the hardware store with you. There are hundreds of models. Even if you think you know the brand, there are subtle differences in length and notch placement that make a huge difference. Getting the exact match is the only way to ensure the leak stays gone.
Dealing with Compression Faucets
If you have an older house, you probably have a compression faucet. These work like a screw. When you turn the handle, it pushes a rubber washer down against a metal "seat" to block the water.
When these leak, it’s almost always the washer. Once you get the handle off, unscrew the stem. At the very bottom, you’ll see a small rubber disk held on by a brass screw. If that disk looks flattened or chewed up, replace it.
But here is the secret: Check the seat. The seat is the metal part inside the faucet body that the washer presses against. If the seat is pitted or scratched, a new washer won't do anything. It’ll leak within a week. You can buy a "seat dresser" tool for about $10 that smooths the metal back down, or you can just replace the seat entirely if it has a hex-shaped hole for a wrench.
Reassembly and the "Grit" Problem
You’ve got your new parts. You’ve cleaned off the lime and scale with vinegar. You’ve applied a tiny bit of plumbers' grease to the new rubber seals. Now, put it all back together in the reverse order.
Don't over-tighten the bonnet nut. Snug is good. "Hulk-smash" tight will crack the plastic housing.
Before you turn the water back on, remove the aerator. That’s the little screen at the very tip of the spout where the water comes out. Why? Because when you turn the water back on, the sudden rush of pressure often knocks loose bits of rust or scale from the pipes. If the aerator is on, that junk gets trapped right at the finish line, and your brand-new fix will result in a pathetic, weak stream of water.
Turn the water valves under the sink back on slowly. Let the water run through the open faucet for a minute to flush out any debris. Then, screw the aerator back on.
When to Give Up and Buy a New Faucet
Sometimes, the metal body of the faucet is just done. If you see water seeping through the actual metal (porosity) or if the internal threads are completely corroded away, no amount of new washers will help.
If you’re spending more than $50 on parts for a basic faucet, honestly, just buy a new one. A decent mid-range faucet costs around $80 to $120. If yours is a "builder grade" special that came with the house 15 years ago, it’s served its time. Let it go.
Real-World Nuance: The Delta Ball Valve
Delta faucets often use a ball valve system instead of a cartridge. It looks like a stainless steel ball with holes in it sitting on top of two rubber "seats" and springs.
If you have this setup, don't just replace the ball. Replace the seats and springs too. They cost about $5 for a kit. The springs lose their tension over time, and the rubber seats get brittle. It’s the most common point of failure for this design. Use a pen or a small screwdriver to fish the old springs out of the holes inside the faucet body. Drop the new ones in, put the seats on top, and drop the ball back in. It’s like a 10-minute fix that makes the faucet feel brand new.
Critical Safety Check
Always check for leaks after you think you’re done. Don't just turn it on, see it works, and walk away. Leave the cabinet doors open and put a dry paper towel under the supply lines. Come back in an hour. If the towel is damp, you’ve got a slow leak at one of the connections. It’s better to find that now than to find a moldy cabinet floor three months later.
Actionable Next Steps
To get started right now, clear everything out from under your sink so you actually have room to move. Grab a flashlight and identify the brand of your faucet—it’s usually etched right on the base or the handle. Once you have the brand, search for that specific model’s "exploded view" diagram online. This will show you exactly which seals and cartridges are inside before you ever pick up a wrench. If you can’t find a brand name, take a clear photo of the faucet to the plumbing aisle of a local hardware store; the grey-haired folks working there can usually identify a cartridge just by looking at the handle shape. Finally, ensure you have a small bucket or towel ready to catch the "trickle" that inevitably happens when you pull the cartridge out of the valve body. Once the new part is in, your drip—and that annoying sound—should be a thing of the past.