What Is a Flow Restrictor?
Quick answer
The disc that caps a shower head's flow by law. Usually blamed for weak showers, rarely guilty.
The small plastic disc inside a shower head that caps output at the federal 2.5-gallon-per-minute limit. It's often blamed for weak showers, but a shower that used to be strong and faded is almost always scaled-up nozzles, not the restrictor. The restrictor never changes, so it can't explain pressure that got worse over time.
Fixes that use this
Bathroom
Low Shower Water Pressure? Fix It in One Evening
Weak shower pressure is usually a mineral-clogged head, not your pipes. Soak it in vinegar, check the inlet screen, and know when it's something bigger.
Time20 min active + 1–2 hr soak Cost$2–$25 moderate