You turn on the faucet, and instead of a powerful stream, you get a sad, weak trickle. You sigh and assume the city is doing maintenance again. But if this has been happening for weeks, the city is innocent.

The culprit is likely a brass component in your basement called the Pressure Reducing Valve (PRV). City water actually arrives at your house at a dangerously high pressure (often 100+ PSI). The PRV’s job is to "throttle" that pressure down to a safe 50-60 PSI. But like any mechanical part, it has a lifespan. After 15 years, the internal diaphragm fails.

"When a PRV fails, it usually fails in one of two ways: 'Open' (causing dangerous high pressure) or 'Choked' (causing the frustrating low pressure you are feeling now). It’s essentially a clogged artery in your home’s circulatory system."

The $10 Diagnosis Tool

You don't need to call a plumber to confirm this. You need a $10 tool from the hardware store: a Water Pressure Gauge.

Screw the gauge onto any outdoor spigot (hose bibb) or the drain valve on your water heater. Turn on the spigot and read the dial:

Below 40 PSI: Your PRV has failed in the "Choked" position. It is restricting flow even when you need it.
Above 80 PSI: Your PRV has failed "Open." This is actually worse—it puts your pipes, water heater, and washing machine hoses at risk of bursting.
Normal Range: Ideally, you want to be between 50 and 60 PSI.

Can You Adjust It?

Maybe. Locate your PRV (usually on the main line coming into the house). On the very top of the bell shape, there is a bolt with a lock nut.

The Trick: Loosen the lock nut and turn the bolt Clockwise to increase pressure. Have someone watch the gauge while you turn. If the pressure rises, you saved yourself $300. If you turn the bolt and the needle doesn't move (or if the bolt is seized with rust), the internal spring is broken. It is time to replace it.

Global vs. Local Low Pressure

Before you touch the valve, verify one thing: Is the pressure low everywhere?

If only the kitchen sink is weak, but the shower is fine, you have a clogged aerator or a kinked supply line under the sink. The PRV controls the entire house. If the problem is global, the PRV is guilty.

Get Your Flow Back

A failing PRV isn't just annoying; it puts stress on your appliances. Swapping it out is a standard job for a plumber, or a moderate DIY project if you are handy with a wrench.

Need to test your PSI? We have rated the Best Home Water Pressure Gauges of 2026. Click below to find out if your house is suffering from "Choked Artery Syndrome."

Low Water Pressure? It’s Not the City. It’s Your "PRV" Valve.