When you begin to notice a loss in water pressure in your shower but nowhere else, chances are the flow restrictor is clogged. All manufacturers, including Moen, now place flow restrictors in the neck of the shower head to help conserve water. To eliminate the low-water pressure problem requires removing the flow restrictor from the Moen shower head. When removing pieces from inside the shower head, use care so that you do not accidentally damage the threads inside the shower head.
Place a cloth over the shower-head connection and tighten the jaws of an adjustable wrench securely over the cloth and connector. Hold the shower pipe with one hand near the shower wall and turn the shower-head connector with the wrench counterclockwise. Remove the shower head from the shower pipe.
Remove the rubber O-ring gasket out of the neck of the shower head with your finger. Do not use pliers or a screwdriver to remove the O-ring because you could damage it. Turn the shower head neck over into the palm of your hand to shake the screen loose. Set the screen and the O-ring aside.
Insert the corner tip of a flat-head screwdriver into the center of the flow restrictor. The flow restrictor is the flat plastic piece in the shower head neck with several small perforations that resembles an aerator on a faucet.
Pry the flow restrictor out of the shower head neck with the screwdriver. Use care around the inner threads of the shower head so that you do not damage the threads.
Insert the screen back into the shower head and insert the O-ring until it is firmly against the screen. Wrap plumbers tape around the shower arm threads. Thread the Moen shower head back onto the shower arm until you can no longer turn it by hand.
Lay the cloth over the connection and hold the shower arm with one hand. Turn the connection another three-quarter turn with the adjustable wrench.