A whistling sound while the shower is running is a symptom of fixture or pipe problems. Shower water runs through pipes, valves and a flow restrictor before it reaches the holes in the shower head. A cartridge-type shower faucet may simply need a new cartridge, but a washer-type faucet requires more intricate repairs.
If you do not have a socket wrench, Phillips screwdriver or other necessary tools, you can hire a licensed plumber to make repairs. Before you undertake repairs, use the shut-off valve near the shower or in the basement or crawl space to turn off the water.
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Whistling Sounds From Shower Head
Mineral deposits, copper shavings and plastic fragments can clog the flow restrictor disk or the holes in the shower head and cause a whistling sound. To check for debris, unscrew the shower head from the pipe in the wall and pry out the small plastic disk from the shower head.
You can poke out deposits from the disk with a pin or, according to Faucet Depot, soak the shower head in warm white vinegar for a few hours and scrub with a toothbrush. Rinse the shower head and disk, run water through the pipe to flush out debris, and reassemble and attach the shower head to the pipe.
Check for a Worn Washer
A loose or worn washer in the faucet's shower diverter valve may be responsible for that whistle. After years of wear or mineral accumulation, a washer can stretch out or harden. Hot water can also soften a washer in the hot side of the faucet and produce a whistle when the hot water is running.
You can remove the faucet handle, escutcheon plate and stem from the shower wall and remove the washer from the diverter valve yourself; take a damaged washer to a hardware store to find a replacement. If you prefer, you can hire a plumber to check and replace the washer.
Pipe Too Narrow
Water flows faster and creates higher pressure through a narrow pipe than through a wide pipe. Buy a water pressure gauge and test the pressure of the pipe that leads to the shower faucet.
According to Fast Plumbers, if the gauge reads greater than 70 pounds per square inch, you can lower the pressure and eliminate the whistling sound by replacing the narrow pipe with a slightly larger pipe. For example, replacing a 1/2-inch pipe with a 3/4-inch pipe may solve the problem.
Check the Supply Lines
Although the whistling sound occurs when you turn on the shower, the problem may be deep in your home's water supply lines. As water rushes to your shower, mineral deposits or worn valves or washers in the lines may produce a whistling sound.
A plumber can replace washers and valves, perform an acid flush to reduce buildup, or install an expansion tank to relieve pressure in your water heater. Pipe insulation, such as polyethylene foam wrap, minimizes noise from supply lines and improves energy efficiency in hot water pipes.