What causes low water pressure?

Diagnose by scope

• Single fixture, both hot and cold weak → clogged aerator or worn cartridge
• Single fixture, hot only → water heater shutoff partly closed or a restricted supply line
• Whole house, gradual decline over months → aging galvanized pipe narrowing internally, or a pressure regulator drifting out of range
• Whole house, sudden drop → a valve accidentally closed, utility work nearby, or a new leak in the supply line

Measure before replacing parts

A pressure gauge threaded onto an outdoor hose bib gives a real number in minutes. Most homes run comfortably at 40–60 psi; below about 40 psi feels noticeably weak. Testing avoids replacing fixtures or a water heater to solve what's actually a system-level pressure problem.

Urgent vs. can wait

Gradual, mild pressure loss across the house can typically be scheduled for a normal appointment. A sudden, severe drop — especially with a hissing sound, a wet spot outside, or a spike in the water bill — suggests an active leak and deserves prompt attention.

What a plumber checks

• Pressure at multiple points (hose bib, inside fixtures) to isolate whole-house vs. localized issues
• The pressure-reducing valve, if the home has one, for correct setting and function
• Visible and accessible piping for corrosion, especially at older galvanized sections
• The water meter for movement indicating a hidden leak

South Florida notes

Homes built before the 1970s in older Miami-Dade and Broward neighborhoods sometimes still have galvanized steel supply lines, which corrode and narrow from the inside over decades and are a common source of whole-house pressure loss that a plumber can confirm by checking pipe material at an accessible point.