Fix it
Why is my water pressure low?
The first diagnostic split costs nothing: is it one fixture, the hot side only, or the whole house? Each answer sends the search somewhere completely different, and two of the three usually end without a service call.
What it usually is
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One fixture: a clogged aerator or cartridge
Mineral grit collects in the little screen at the spout and in the valve cartridge behind the handle. Unscrew the aerator and compare flow without it — the thirty-second test.
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Hot side only: restriction at or after the water heater
Sediment at the heater outlet or a partially closed valve on the hot line throttles every hot tap while cold runs strong.
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Whole house: a failing pressure regulator
The bell-shaped regulator where the main enters fails toward weak (or occasionally toward harsh). A gauge on the outdoor spigot reading well under 50 psi points here.
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Whole house on old galvanized pipe: corrosion choking the bore
Decades of internal rust narrows galvanized supply lines until pressure at the far fixtures dwindles. This one is a repiping conversation, honest but bigger.
What you can check yourself
Run the split test above. Soak aerators and showerheads in vinegar. Confirm the main shutoff and any line valves are fully open — half-closed valves after past work are a classic. Put a gauge on a spigot: 50 to 70 psi is the healthy band.
When it’s a job for a pro
Regulator replacement is routine plumber work. Hot-only restriction gets diagnosed at the heater. Galvanized narrowing is worth a professional assessment of which runs matter most — partial repipes often recover most of the pressure for a fraction of the full job.
A regulator typically runs $250 to $600 installed; cartridge and aerator fixes are under $50 DIY. Repiping is quoted by run, so the assessment is the valuable first step.
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