What causes low water pressure?
Short answer
At one fixture, it's usually a clogged aerator or a worn cartridge. Across the whole property, the common causes are a partially closed valve, a failing pressure-reducing valve, corroded galvanized piping, or a leak in the service line.
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Diagnose by scope
- Single fixture, hot and cold → aerator or cartridge
- Single fixture, hot only → heater shutoff or supply line
- Whole house, gradual → aging pipe or regulator drift
- Whole house, sudden → valve, utility work, or a break
Measure before replacing parts
A gauge on a hose bib gives a real number. Most homes run comfortably at 40–60 psi. Testing avoids replacing fixtures to solve a system-level problem.
Related questions
Can a hidden leak lower pressure?
Yes. A significant supply-side leak diverts flow and can reduce pressure throughout the property.
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