How to Fix Low Water Pressure
Low water pressure makes showers miserable and dishwashers ineffective. The fix depends entirely on whether the problem is isolated to one fixture or affects the whole house. Single-fixture low pressure is almost always a clogged aerator or showerhead. Whole-house low pressure has a different set of causes.
Likely Causes
- 1Clogged aerator (single fixture) — mineral buildup blocking the screen
- 2Clogged showerhead — mineral deposits in the nozzles
- 3Partially closed shutoff valve at the fixture or main
- 4Pressure-reducing valve (PRV) set too low or failing
- 5Water supply line corrosion or partial clog (older galvanized pipes)
- 6Municipal supply pressure issue (whole street affected)
Not urgent for safety, but can signal a failing pressure-reducing valve or pipe corrosion worth investigating.
How to Fix It: Step by Step
- 1Test the scope of the problem
Check pressure at multiple fixtures. If it's only at one sink, the aerator is the likely cause. If it's only in the shower, the showerhead is clogged. If it's whole-house, check the main shutoff and PRV.
- 2Clean or replace the aerator
Unscrew the aerator at the tip of the faucet (turn counterclockwise). Soak in white vinegar for 30 minutes. Rinse and reinstall. If the screen is broken, replace the aerator ($3–$8).
- 3Clean the showerhead
Remove the showerhead or fill a plastic bag with white vinegar and rubber-band it over the head. Soak for 2–4 hours. Use a toothpick to clear blocked nozzles.
- 4Check all shutoff valves are fully open
Locate the main shutoff and any branch shutoffs. They should all be turned fully counterclockwise (open). Gate valves that are partially open can significantly reduce pressure.
- 5Check and adjust the PRV
The PRV is typically a bell-shaped valve on the main supply line near where it enters the house. Attach a pressure gauge to a hose bib to check pressure. Normal is 40–80 PSI. Adjust the PRV's adjustment screw if needed.
Materials & Tools Needed
Warning Signs It's Getting Worse
- ⚠Pressure drops suddenly and doesn't recover
- ⚠Brown or rusty water alongside low pressure
- ⚠Low pressure on both hot and cold lines (supply issue vs. water heater issue)
When to Call a Professional
Call a plumber if pressure is low throughout the whole house and all valves are open — the PRV may need replacement. Also call if you have older galvanized steel pipes, which corrode from the inside and may need replacement.
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