Low Water Pressure Diagnosis & Repair
Low pressure is a symptom, not a diagnosis. The fix ranges from a ten-minute aerator clean to a repipe, so finding the actual cause first matters a lot.
Narrowing it down
One fixture only
Almost always local: a clogged aerator, a partially closed angle stop, or a failing cartridge. Cheap and quick.
Hot water only
Points at the water heater or the hot side specifically. Sediment, a failing dip tube, or scaling in a tankless unit.
Whole house, gradually worse over years
Classic galvanized corrosion. The pipe diameter has been closing for decades. This is the repipe conversation - see repiping.
Whole house, suddenly
A failed pressure regulator, a partially closed main valve, or a supply-side problem. Sudden change points to a single failed component.
Pressure fine but drops when a second tap opens
Undersized or restricted supply somewhere in the system.
The things people miss
Pressure regulators are wear items
A PRV has roughly a decade of useful life. Many San Diego homes are running well past that on the original unit.
High pressure is a problem too
Above about 80 psi you get water hammer, dripping relief valves, and shortened fixture life. Pressure that is too high damages more than pressure that is slightly low.
A hidden leak lowers pressure
If pressure dropped and your bill rose, stop reading and check the meter with everything off - see leak detection.