Dear customer,

Netro uses the area and depth flow rate(inch/hour) to calculate the water usage is that when the sprinkler system is professionally designed and installed, the zone is usually covered evenly, which means the large the zone is, the more sprinkler heads it needs. So the equation we use is 

Area(inch^2) x depth flow rate (inch/hour) x time (hour) = water usage(inch^3)

Here are some typical flow rate: 
MISTER: 2 inch/hour
FIX_SPRAY_HEAD: 1.5 inch/hour
BUBBLER/ROTOR_HEAD: 1.0 inch/hour
ROTARY_NOZZLE: 0.7 inch/hour
ROTARY_EMITTER: 0.5 inch/hour

If you switched from spray to drip irrigation, it does decrease the water usage.

Thanks,

Wency

Netro Support