High-Efficiency faucets are those that use 0.5 or less gallons of water per minute gpm. The target flow rate for a lavatory faucet is 0.5 gpm for nonmetered and 0.125 gallons per cycle (gpc) for metered. Most manufactures make high-efficiency aerators for both manual and metering faucets. Touchless faucets with sensors should not use batteries and should be either hardwired or have photocell powered sensors.