Low water pressure in a single faucet usually means the problem is local to that fixture or its supply line. Common causes include a clogged aerator, a partially closed shutoff valve, or issues with the faucet cartridge. You can often fix these yourself by cleaning or replacing the aerator, fully opening the shutoff valve, or inspecting the cartridge before calling a plumber.
Why is only one faucet having low water pressure?
When only one faucet has low water pressure, the issue is likely limited to that faucet or its immediate water supply. Common causes include a clogged aerator or screen at the faucet tip, a shutoff valve under the sink that isn’t fully open, or debris trapped inside the faucet cartridge. Unlike problems that affect the entire house, such as a main water supply issue or widespread pipe blockage, these local issues are easier to identify and fix.
Could the faucet aerator or screen be clogged?
The aerator is a small mesh screen screwed onto the faucet spout to regulate water flow. Over time, minerals from hard water or debris can clog it and reduce water pressure. Signs include a weaker water stream or sputtering flow. Checking and cleaning the aerator is a quick first step and often restores normal pressure.
Is the shutoff valve fully open or partially closed?
Each faucet has a shutoff valve near or under the sink controlling its water supply. If this valve is partially closed, it restricts water flow and lowers pressure. To check, find the valve handle and turn it counterclockwise until it stops. Don’t force it beyond that point. Opening a partially closed valve usually restores normal pressure immediately.
How to safely clean or replace the faucet aerator and screen
- Locate the aerator at the end of the faucet spout.
- Unscrew the aerator by turning it counterclockwise. Use pliers wrapped in cloth if it’s tight to avoid scratching.
- Inspect the screen and parts for mineral buildup or debris.
- Rinse the parts under running water. Use an old toothbrush to scrub gently or soak them in vinegar for about 30 minutes to dissolve minerals.
- Rinse thoroughly and reassemble the aerator.
- Screw it back on by turning clockwise until snug. Don’t overtighten.
- Turn on the faucet to see if pressure improves.
If cleaning doesn’t help or the aerator is damaged, replace it with a new one from a hardware store using the same method.
How to check for pipe blockages or faucet cartridge issues
If cleaning the aerator and fully opening the shutoff valve doesn’t fix the problem, the issue might be inside the faucet or supply pipes.
To inspect the faucet cartridge (which controls water flow inside many faucets):
- Turn off the water supply at the shutoff valves.
- Remove the faucet handle by unscrewing visible screws or caps.
- Carefully take out the cartridge. You might need a cartridge puller or gently pry it out.
- Look for mineral buildup, damage, or debris.
- Clean it with vinegar or replace it if worn or broken.
If you suspect a blockage in the supply pipes beyond the faucet, such as sediment buildup, this is harder to fix yourself. Old or corroded pipes may require professional inspection and repair.
How to test the faucet water pressure after fixes
After cleaning or replacing the aerator, opening the shutoff valve fully, or servicing the cartridge, turn the faucet on at full flow to check the pressure.
Look for a steady, strong stream without sputtering or dripping. Compare the flow to another faucet with normal pressure to see if it feels similar.
If pressure is still low, turn the faucet on and off a few times to clear any loosened debris. If the problem continues, it may be deeper in the plumbing or require parts or repairs beyond DIY.
When should you call a plumber?
Call a plumber if you’ve cleaned the aerator, checked the shutoff valve, and inspected the cartridge but the pressure remains low. Also, if you find leaks while taking apart the faucet or feel unsure about handling internal parts, professional help is best.
Persistent low pressure in one faucet can indicate corrosion or damage in the supply line, which needs specialized tools and parts to fix. Don’t hesitate to call a plumber to avoid causing further damage.
Conclusion
Start by cleaning the aerator and confirming the shutoff valve is fully open. If those don’t fix the problem, inspect the faucet cartridge for clogs or damage. Test water flow after each step to see if pressure improves. If it doesn’t, call a plumber who can diagnose and repair deeper plumbing issues. These steps can often restore normal flow without an immediate service call.
Frequently Asked Questions
Can a clogged aerator cause low water pressure in just one faucet?
Yes, mineral buildup or debris in the aerator commonly reduces flow from a single faucet. Cleaning or replacing it usually fixes the issue.
How do I know if the shutoff valve is causing low pressure?
If the valve under the sink isn’t fully open, it restricts water flow. Turning it counterclockwise until it stops usually restores normal pressure.
Is it safe to replace the faucet cartridge myself?
You can replace the cartridge safely if you turn off the water supply first and follow instructions carefully. If you’re unsure or encounter leaks, it’s best to call a plumber.