Low water pressure is one of those problems that starts as a minor annoyance — a weak shower, a faucet that takes forever to fill a pot — and slowly drives you crazy. The fix can be simple or complicated depending on the cause, so let’s work through the most likely culprits.
First: Is It the Whole House or Just One Fixture?
This is your most important diagnostic question. Turn on a faucet in the kitchen and one in the bathroom at the same time. Check the outdoor spigot. If pressure is low everywhere, the problem is likely at the supply level — your main shutoff valve, pressure regulator, or the municipal supply itself. If it’s only one faucet or one shower, the issue is localized to that fixture.
Whole-House Low Pressure
Partially Closed Main Shutoff Valve
Locate your main water shutoff (usually near the water meter, in the basement, or in a utility closet). Make sure it’s fully open. After service work or a pipe repair, these sometimes get left partially closed — and that alone can cut pressure significantly.
Failing Pressure Regulator
Most homes have a pressure-reducing valve (PRV) that keeps water pressure between 45–80 PSI. These can fail after 10–15 years, causing pressure to drop (or sometimes spike dangerously). A plumber can test the PRV and replace it if needed — it’s typically a $200–$400 repair.
Old, Corroded Pipes
Galvanized steel pipes, common in homes built before the 1970s, corrode from the inside over decades. That corrosion narrows the pipe’s interior diameter and chokes flow. If your home has galvanized supply lines and you’re experiencing widespread pressure issues, it may be time to repipe — a bigger investment but a long-term fix.
Single-Fixture Low Pressure
Aerators — the small mesh screens at the tip of faucets — clog with mineral deposits over time. Unscrew the aerator, soak it in white vinegar for an hour, scrub it with an old toothbrush, and reinstall. Same goes for showerheads. This often completely solves low pressure at a single fixture.
When to Call a Plumber
If you’ve checked the shutoff, cleaned aerators, and pressure is still low throughout the house, call a licensed plumber to test your PRV and inspect the supply lines. Don’t ignore the problem — low pressure can be a symptom of a leak somewhere in the system.