Water restrictors, commonly called flow restrictors, are designed to reduce the water flow in a shower head to 2.5 gallons per minute. The National Energy Act requires that shower head manufacturers install a flow restrictor or flow controller in shower heads. The water restrictor is intended to save people money on water and energy bills, but if you live in an area with low water pressure, the flow restrictor can reduce your shower to a thin drizzle of water. Removing the water restrictor will return your shower pressure to normal, but it may also increase your water bills.