What Causes Low Water Pressure In A Single Faucet?
I’ll never forget the day I turned on the bathroom sink, and it felt like I was trying to wash my hands under a leaky water bottle. Everything else in the house? Great pressure. But that one faucet? Barely a trickle.
If you’re dealing with the same thing — great water pressure everywhere except one faucet — the good news is this: it’s usually an easy fix. You just have to figure out what’s clogging things up.
Let me walk you through what I discovered in my own home and how I got the pressure back fast without spending a dime on a plumber.
Check This First: Is It Just Hot, Cold, or Both?
Here’s a trick I learned the hard way: turn on both the hot and cold taps separately.
If only the hot water is weak, it could be a water heater or sediment issue in the hot water line.
If both hot and cold are low, it’s usually something closer to the faucet itself.
Either way, knowing this helps you narrow down the real problem fast.
1. A Clogged Aerator (The #1 Culprit)
This was the issue in my case. The tiny screen at the end of your faucet, called the aerator, can get clogged with:
- Mineral buildup
- Sand or rust from old pipes
- Debris from municipal repairs or maintenance
All you have to do is unscrew it (pliers help), rinse it, soak it in vinegar if it looks crusty, and screw it back on. That alone can boost pressure like night and day.
If it’s damaged, you can grab a replacement at any hardware store for a few bucks.
2. A Partially Closed Valve Under the Sink
There’s a small shut-off valve under most sinks — sometimes two (one for hot, one for cold). These valves can get nudged partially closed without you realizing it, especially during plumbing work or housecleaning.
Check under the sink and make sure both valves are fully open. It sounds too easy to be the answer, but I’ve seen this solve the issue more than once.
3. Buildup Inside the Faucet or Supply Lines
Even if your aerator is clean, there could be gunk inside the faucet body itself or in the short supply line hoses under the sink.
I once had a faucet where the cartridge was partially blocked by hard water minerals. Disassembling the faucet and flushing it cleared everything up. You can usually find your faucet’s model online and watch a video on how to remove the cartridge or filter for cleaning.
4. A Faulty or Old Faucet Cartridge
If you’ve got a modern single-handle faucet, it likely uses a cartridge that controls the water flow. Over time, these wear out or get clogged.
In one case, I replaced an old cartridge and my pressure doubled instantly.
Need a full guide on boosting water pressure in the whole house too? I’ve got you covered right here:
👉🏼 How to Fix Low Water Pressure in Your House Fast
5. Gunk in the Water Heater (If It’s Only Hot Water)
If the cold water flows strong but hot water drips, your water heater might be clogged with sediment.
You can flush it out yourself. I did this last spring and couldn’t believe how much junk came out. My hot water pressure improved across every faucet in the house.
Learn how to do it step-by-step:
👉🏼 Why Is My Water Heater Making a Popping Noise?
That same popping sound is often caused by the same sediment that lowers your hot water pressure.
6. Bent or Clogged Supply Line Hose
Those flexible hoses under your sink can kink like a garden hose, especially during installation or if they’ve been bumped around.
Turn off the valves, disconnect the hoses, and check them. Blow through them or run water through into a bucket. If they’re gunked up or bent, you’ll know right away.
7. Airlocks or Water Hammer Issues
Sometimes air can get trapped in a pipe and create an airlock, or a sudden water shutoff can cause a water hammer that stirs up sediment and causes partial blockages.
In either case, turning on all the faucets in the home (hot and cold) for a few minutes can help clear air or dislodge debris.
Don’t Forget to Test With a Water Pressure Gauge
If you’re not sure how bad the pressure is or want to measure improvement, grab a water pressure test gauge. I use this simple one that screws onto any hose bib:
👉🏼 Check Out the Best Water Pressure Gauge Test Tool
It’s super helpful for diagnosing not just one faucet but your entire system.
When It’s NOT a DIY Fix
In rare cases, the issue could be further down the line:
- A broken pipe
- A bad pressure regulator
- Major corrosion inside the walls
If none of the above steps solve it, and other faucets start to act up too, it may be time to call a professional. But for one single faucet? 99% of the time, you can fix it yourself.
Get That Faucet Flowing Again
Low water pressure in one faucet is frustrating — but it doesn’t have to stay that way.
Start by cleaning the aerator, check your under-sink valves, and flush the faucet lines. These quick checks usually fix the problem faster than you’d think.
And if you’re dealing with multiple low-pressure problems or just want to get ahead of it all, take a look at this full DIY guide:
👉🏼 Fix Low Water Pressure Fast Without a Plumber
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