Check Water Pressure in the Whole House
Before we get to the shower, how’s the water pressure in the rest of the house? To find out, buy a water-pressure gauge—they cost about nine bucks at home centers—and screw it to a hose bib, like the one on an outdoor faucet. The gauge should read between 40 and 60 psi when you open the bib’s valve. If the pressure is in that range, then something is restricting the flow to your shower.
First, see if the showerhead is clogged. Remove it and measure how much water flows out of the shower arm and into a bucket in 10 seconds. If you collect between 1⅓ and 1⅔ gallons—the equivalent of 8 to 10 gallons per minute—then the head is the culprit. If the flow is less than that, then clean or replace the shower valve.
Pressure-Reducing Valve
Now, if the gauge shows that the entire house has low water pressure, then try adjusting the pressure-reducing valve.
Look on the main supply pipe near your water meter for a conical valve that has a bolt sticking out of the cone. To raise pressure, turn the bolt clockwise after loosening its locknut. Keep an eye on the gauge to make sure the pressure is within bounds, then retighten the locknut.
If that adjustment doesn’t help, then the municipal pressure itself may be inadequate. Start by talking to your neighbors. If their pressure is good, then call the water company to check the shutoff valve out by the street. But if your neighbors’ water pressure is low, too, there’s only one thing left to do: Install a water-pressure booster, like the ones made by Amtrol. It consists of an electric pump that feeds water to a tank that keeps the water at the desired pressure. For More: How to Install a Water Pressure Reducing Valve; How to Install a Water Pressure Booster—This Old House plumbing and heating expert Richard Trethewey
