How does the water-saving faucet work？

Low-flow faucets and shower heads sound like they deliver low water pressure, but that’s not too appealing to a homeowner who’s working at the kitchen sink or trying to start off the day with an invigorating shower. In actuality, good low-flow or water-saving faucets and shower heads deliver what feels like full-volume water. They provide equal or better performance than conventional fixtures, while saving water costs, water heating costs, sewage costs, and more.

A conventional shower head is rated to use 3 to 7 gallons per minute (gpm) at normal water pressure (80 psi). At these rates, a 5-minute shower uses 15 to 35 gallons of water. In contrast, a 5-minute shower with a water saving shower head that delivers 1.0 to 2.5 gpm consumes only 5 to 12.5 gallons of water. How is this possible without reduced performance for the homeowner?

Low-flow shower heads that are designed to federal standards (2.5 gpm at 80 psi) typically incorporate a narrower spray area and a greater mix of air and water than conventional shower heads. As a result, the shower head uses less water, yet the homeowner perceives no difference in quality or comfort. Features of these low-flow shower heads include: atomizers that deliver water in small but abundant droplets to cover larger surface areas; pulsators that vary spray patterns with pauses between spurts or by pulsating between strong flow and light mist; and aerators that mix water droplets with air to cover the desired surface area. In addition, flow regulators on the shower controls can reduce or stop the water flow when the homeowner is shampooing or soaping.

Low-flow faucets designed to federal standards (2.5 gpm at 80 psi) use sensors, as well as aerators, to reduce water consumption while maintaining comfort levels. Homeowners can select from several new low-flow faucet technologies for kitchens and baths, including a metered-valve faucet that delivers 0.25 gallons of water and then automatically shuts off. Self-closing faucets are spring-loaded to shut off the faucet a few seconds after the user turns it on. Ultrasonic, or infrared-sensor, faucets automatically activate the water flow when hands are detected beneath it, and automatically shut off the water when the hands are removed. Foot controls allow homeowners to activate a faucet at a set temperature by tapping their foot to a pedal. Finally, a simple and inexpensive retrofit for a conventional faucet is replacing the screw-in tip of the faucet with an aerator.