Why is water pressure low at just one faucet?
One tap or shower runs weak while every other fixture in the house is normal.
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Key takeaways
- This is usually not an emergency, but it does not fix itself and it gets worse if you leave it.
- Most likely cause: Clogged aerator or showerhead.
- Do this first: Unscrew the aerator or showerhead, clear the screen, and reinstall.
- Call right away if the weak fixture is also leaking behind the wall or into a cabinet.
- The repair starts with: Clean or replace the aerator and showerhead.
What it is
Low water pressure at one fixture Low pressure at a single fixture, while every other tap runs normally, means the restriction is local to that fixture, most often a clogged aerator, a failing cartridge, or a kink in its supply line.
It is not urgent, but it usually needs a plumber only if cleaning the aerator and checking the shutoff valve does not restore flow.
The short answer
Low pressure at a single fixture is a local problem, not a house problem. The most common cause is a clogged aerator or showerhead full of mineral scale, followed by a partly closed angle stop under the sink, a failing cartridge inside the faucet, and a kinked or corroded supply line. Because the rest of the house is fine, the main and the pressure reducing valve are not involved, which keeps this an inexpensive fix in most cases.
What it usually means
These are the causes we find most often, ranked from most likely to least.
- 1
Clogged aerator or showerhead
Most likely
Hard water scale and debris block the screen. Unscrew, soak, and rinse.
- 2
Angle stop not fully open
Common
The shutoff valve under the fixture was left partly closed after other work.
- 3
Worn faucet cartridge or mixing valve
Common
Internal wear restricts flow, often on the hot side first.
- 4
Kinked or corroded supply line
Less common
Flexible connectors kink behind the cabinet or corrode at the fitting.
- 5
Localized pipe scale or a partial blockage in the branch
Occasional
Older branch piping narrows and only that fixture suffers.
What to do right now
- 1Unscrew the aerator or showerhead, clear the screen, and reinstall.
- 2Open the angle stops under the fixture fully.
- 3Test hot and cold separately to see whether one side is weaker.
- 4Look under the sink for kinked or leaking supply connectors.
When it is an emergency
- The weak fixture is also leaking behind the wall or into a cabinet.
- Pressure drops at other fixtures over the following days, which points to a larger supply problem.
What the fix involves
Most of these are solved with a cleaning or a cartridge. Where the branch piping is scaled or the connectors have failed, that section is replaced so the fixture gets full flow again.
- 1Clean or replace the aerator and showerhead.
- 2Verify the angle stops and supply connectors.
- 3Replace the faucet cartridge or mixing valve.
- 4Replace the restricted branch piping where cleaning does not restore flow.
What drives the cost
Every job is quoted before work begins. These are the factors that move the number on this kind of repair.
- Cleaning versus cartridge replacement versus branch repiping
- Fixture brand and parts availability
- Access behind walls or inside tight vanities
Related problems homeowners ask about
Why is water pressure low in my whole house?
Weak flow at every tap, showers that lose force when another fixture runs, and appliances that take much longer to fill.
Read this nextWhy are my pipes whistling?
A high pitched whistle or squeal when water runs, sometimes only at partial flow or only when a toilet refills.
Read this nextWhy is my water brown or discolored?
Water runs brown, yellow, or reddish, sometimes with visible grit, and it may stain fixtures and laundry.
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Licenses, credentials, and company proof
- Colorado Master PlumberLicense MP-18927
- Colorado State Plumbing ContractorLicense 2110
- Family Owned & OperatedServing Denver since 2006, 20 years
- Better Business BureauAccredited Business, A+ rating
- Angie's List Super Service Award2012 through 2017
- Serving Denver since 2006Residential and commercial properties across the metro
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Straight answers on what low water pressure at one fixture work costs, how fast we can get out, and what stands behind the repair.
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