How to Fix Low Water Pressure in Whole House

How to Fix Low Water Pressure in the Whole House

When every faucet, shower, and appliance in your home has low water pressure, the problem is with your home's water supply system — not individual fixtures. Here's how to diagnose and fix it.

Step 1: Measure Your Water Pressure

Before troubleshooting, measure your actual water pressure:

👉 Water pressure gauge — attach to an outdoor hose bib or laundry faucet. Normal household pressure is 40–80 PSI. Below 40 PSI is considered low.

Cause 1: Main Shut-Off Valve Not Fully Open

The main water shut-off valve (where water enters your home) may not be fully open — especially if it was recently turned off for repairs.

Fix:

• Ball valve (lever handle): Make sure the lever is parallel to the pipe — fully open
• Gate valve (round wheel handle): Turn counterclockwise until it stops — fully open
• Test pressure after opening fully

Cause 2: Pressure Reducing Valve (PRV) Failing

Most homes have a pressure reducing valve (PRV) where the water line enters the house. It regulates incoming pressure to a safe level. When it fails, it can restrict pressure too much.

How to tell: Pressure is low throughout the house, the main valve is fully open, and the PRV is more than 10–15 years old.

Fix: Try adjusting the PRV first — there's a screw on top. Turn clockwise to increase pressure. If adjusting doesn't help, replace the PRV:

👉 Pressure regulating valve — set to 60 PSI, fits 3/4 inch NPT. Replacing a PRV is a moderate DIY job — turn off the main water, cut out the old valve, install the new one with PTFE tape on threads.

Cause 3: Corroded or Undersized Pipes

Older homes with galvanized steel pipes often develop internal corrosion that narrows the pipe diameter over decades, progressively reducing flow and pressure.

Signs: Pressure has been declining gradually over years. Water may have a slight rust color.

Fix: Pipe replacement — this is a major project that typically requires a plumber. Replacing galvanized pipes with copper or PEX restores full pressure.

Cause 4: Municipal Supply Issue

Sometimes the problem is with the city water supply, not your home's plumbing. Check with neighbors — if they have the same issue, contact your local water utility.

Cause 5: Water Meter Valve Partially Closed

The valve at the water meter (usually at the street or in a box near the foundation) may be partially closed.

Fix: Use a water meter shut-off key to access and fully open the meter valve. Note: in some areas, only the utility company is authorized to operate the meter valve.

Quick Diagnosis

Bottom Line

Start by checking the main shut-off valve — it's the easiest fix and takes 30 seconds. Then measure pressure with a gauge and check the PRV. If pressure has been declining for years, corroded pipes may be the culprit and a plumber should assess the situation.