How to diagnose and fix low water pressure at every faucet in a California home

# Quick summary

# What to check first

• Verify main and shutoff valves are fully open. A valve that's only partway open behaves like a restriction and can mimic larger system failures.
• Read the water meter leak indicator. If it moves with every fixture off, you likely have a hidden leak that can both lower pressure and cause damage.
• Listen and look for visible water: constant toilet fill movement, wet spots near the heater, under sinks, around hose bibs, or in crawlspaces.

# Why a hose-bib gauge test matters

• Low static PSI at the hose bib → supply-side limitation, PRV issue, or utility service problem.
• Normal static PSI but weak flow at multiple fixtures → an obstruction or a component that collapses under demand (clogged meter screen, scale, partially closed valve).
• Strong initial pressure that drops quickly when a faucet opens → failing PRV or a restriction that can't sustain flow.

# Distinguish hot vs. cold and single-fixture patterns

• All cold and all hot are weak: look upstream of the water heater (meter/PRV/main valve/service line) or for a whole-house piping restriction.
• Only hot is weak everywhere: suspect the hot-side near the water heater (shutoff, heat-trap nipples, clogged connectors).
• One or two fixtures are weak: check aerators, fixture stops, cartridges, or the local branch piping.

# Immediate safety and leak checks (do these before adjusting settings)

• Confirm the main shutoff is fully open.

• Inspect common leak locations: water heater pan, under sinks, near irrigation valves, and along the service entry.

If you find meter movement with everything off or unexplained wet areas, schedule professional leak detection to locate the issue non-destructively.

# Typical fixes based on the test outcomes

• Utility-side pressure or meter problem: contact the water utility for service checks or repairs.
• Partially closed valve: fully open the valve or have a plumber replace a failing valve.
• PRV drift or failure: have a plumber service or replace the PRV. PRV problems often produce normal-looking static pressure but poor performance under flow.
• Hidden leak: use professional detection and repair to stop water loss and restore pressure.
• Pipe restriction (scale, aging galvanized pipe): remediation can include targeted pipe replacement or cleaning by a licensed plumber.

# Bottom line Start with valve and meter checks, then use a hose-bib gauge test to pinpoint whether the limitation is at the supply, PRV, valve, leak, or early home piping. Targeted repairs based on those observations are more effective than swapping parts at individual fixtures.