How did you settle on the specific performance levels for flow rate across a range of pressures, spray force, and spray coverage?
To ensure performance and user satisfaction under a variety of household conditions, WaterSense has established minimum flow rates at 80, 45, and 20 pounds per square inch (psi) of pressure (the upper, mid, and lower range of potential household pressures). These minimum flow rate requirements are defined as a percent deviation from the maximum flow rate of the showerhead. For instance, the showerhead’s flow rate at 20 psi cannot be less than 60 percent of the maximum flow rate (i.e., a showerhead with a maximum rated flow rate of 2.0 gpm will not flow at less than 1.5 gpm even in a home with very low water pressure). For shower force and spray coverage, WaterSense conducted consumer testing on several different showerheads to determine user preferences for these characteristics. These same showerheads then underwent laboratory testing to determine the quantitative range of performance, and the two data sets were then compared. Based on the characteristics of the showerheads that consu
