How to Fix Low Water Pressure

Low pressure narrows to three causes: a clogged aerator, a bad shut-off, or a supply-side problem at the main.

Common causes

• Clogged aerator or showerhead screen
• Partially closed shut-off valve
• Failing pressure-reducing valve at the main
• Corroded galvanized supply piping

Step-by-step

1. 01Unscrew the aerator and rinse — this fixes ~40% of cases
2. 02Confirm the angle stops under the sink are fully open
3. 03Check pressure at a hose bib with a $10 gauge (should read 40–80 psi)
4. 04If the whole house is low, the PRV or main shut-off is the likely culprit

When to call Northbridge

• Pressure is low at every fixture
• You have rust-colored water (galvanized failing)
• Pressure drops when a second fixture runs
• PRV or main shut-off needs replacement