Ever turned on the bathroom faucet only to get a disappointing trickle while everything else in the house flows fine? If you’re dealing with low water pressure in one faucet, you’re not alone. This common annoyance can have a handful of causes — most of which you can fix yourself.
Low water pressure in one faucet usually means something’s obstructing or limiting the flow in that specific fixture. The rest of your home’s water system may be perfectly fine. In this guide, we’ll help you identify the exact cause and fix it fast, no plumber required for most cases.
Table of Contents
Common Causes of Low Water Pressure in One Faucet
Let’s break down the most common reasons why only one faucet is affected by low water pressure:
1. Clogged Aerator
Quick Summary: Mineral buildup or debris in the screen at the tip of the faucet.
This is the most common cause of low water pressure in one faucet, especially in areas with hard water.
Bathroom and kitchen faucets often have fine mesh aerators that collect calcium, rust, or tiny debris over time.
You might notice the flow is uneven or spraying oddly.
2. Faulty Faucet Cartridge or Valve
Quick Summary: Internal component wear or blockage.
If the faucet handle feels stiff or if water pressure changes suddenly, the faucet cartridge could be damaged or clogged.
This is typical in modern single-handle faucets.
Over time, cartridges can wear out or get stuck, reducing flow.
3. Local Shutoff Valve Not Fully Open
Quick Summary: Partially closed valve under the sink.
Every faucet has individual hot and cold water shutoff valves, usually located in the cabinet below.
If someone recently did plumbing work or bumped the valve, it may not be fully open.
This can lead to reduced pressure on one or both sides.
4. Pipe Corrosion or Sediment Buildup
Quick Summary: Old pipes can clog internally.
Homes with galvanized steel piping are especially vulnerable to internal corrosion.
Sediment buildup can block water flow in just one section of plumbing.
This issue develops over years and may not affect other fixtures.
5. Airlock in the Line
Quick Summary: Trapped air causes irregular pressure.
Happens most often after plumbing maintenance or draining the system.
Can cause water to sputter or flow inconsistently.
Flushing the faucet can usually clear the air.
6. Hot Water Side Only? Check the Water Heater or Mixing Valve
Quick Summary: Sediment or faulty temperature regulation.
If only the hot water side has low pressure, the problem could lie in the water heater.
Sediment can clog the output line, or a faulty tempering/mixing valve can restrict flow.
This issue needs careful inspection, especially if it's happening across multiple fixtures.
Step-by-Step: How to Fix Low Water Pressure in a Single Faucet
Let’s walk through a practical, step-by-step approach to fix low water pressure in one faucet yourself:
Step 1: Check and Clean the Aerator
Time: 10 minutes | Tools: Pliers, vinegar, old toothbrush
- Unscrew the aerator from the tip of the faucet.
- Soak it in white vinegar for 30 minutes to dissolve minerals.
- Scrub with a toothbrush.
- Rinse, reinstall, and test.
Pro Tip: Wrap the aerator with a cloth before using pliers to avoid scratching it.
Step 2: Inspect the Shutoff Valves
Time: 5 minutes | Tools: None
- Open the cabinet below the sink.
- Locate both the hot and cold shutoff valves.
- Turn them counterclockwise to ensure they’re fully open.
- If stuck, gently wiggle — but don’t force.
Step 3: Flush the Faucet
Time: 5 minutes | Tools: None
- Remove the aerator again.
- Turn on the faucet full blast for 20-30 seconds.
- This can clear debris or airlocks from the lines.
- Reattach the aerator and check flow.
Step 4: Replace the Cartridge (if applicable)
Time: 30–60 minutes | Tools: Screwdriver, Allen wrench, replacement cartridge
- Shut off both water supply valves.
- Remove the faucet handle using a screwdriver or Allen wrench.
- Take out the retaining clip and old cartridge.
- Use the manufacturer model to match a replacement.
- Insert the new cartridge, reassemble, and turn the water back on.
Step 5: Call a Pro if Pipe or Valve Issues Are Suspected
If:
The pressure remains low despite cleaning and flushing
There’s visible corrosion or old galvanized pipes
You suspect sediment in the hot water line
…then it’s time to contact a licensed plumber. These deeper issues often require specialized tools or pipe replacement.
Expert Tips for Preventing Future Faucet Pressure Problems
Preventive maintenance is the key to avoiding a repeat of low water pressure in one faucet:
Install a sediment filter or water softener if you live in a hard-water area
Clean aerators every 3-6 months
Flush faucets after any plumbing work to clear debris or air
Schedule a yearly plumbing checkup if your home is 20+ years old
Think of it like changing your oil: small regular steps prevent big expensive problems.
Key Takeaways: What to Do Right Now
If you’re dealing with low water pressure in one faucet, here’s your game plan:
Clean the aerator
Check the shutoff valves under the sink
Flush the faucet to clear air or debris
Replace the cartridge if the flow is still weak
Call a plumber if you suspect pipe damage or sediment blockages
Most fixes are DIY-friendly and inexpensive. Don’t ignore the issue, though, it can get worse over time.
A single faucet with low water pressure is frustrating, but it’s almost always fixable with a little time and know-how. Whether it’s a clogged aerator, a stiff shutoff valve, or a worn cartridge, the steps in this guide will help you get back to full flow.
Still stuck? Oasis Plumbing Miami is here to help. Our North Miami experts can quickly diagnose and resolve stubborn pressure issues before they become major problems.
Call Oasis Plumbing Miami today for fast, reliable service.
Frequently Asked Questions
Why does only one faucet have low pressure but others are fine?
It’s usually a localized issue like a clogged aerator, shutoff valve not fully open, or a faulty faucet cartridge.
Is low water pressure in one faucet a sign of a bigger plumbing problem?
Not usually. It’s typically isolated, unless it worsens or spreads to other fixtures—then it might signal corrosion or a sediment issue.
Can I fix low faucet pressure myself?
Yes. Most issues can be fixed with basic tools and household supplies like vinegar and a toothbrush.
What if only the hot water has low pressure?
Check the water heater and the mixing valve. Sediment buildup or valve malfunctions often restrict hot water flow.
How much does it cost to fix this professionally?
A plumber’s service call for this type of issue usually ranges from $75 to $200, depending on what needs fixing.
