Larger meters are typically venturi tube flow measurement devices, but sonic meters are also used in some locations.
Smaller meters are typically propeller, turbine, or magnetic.
All large meters are read each Monday. These readings are entered into an Excel worksheet and compared with previous month readings to get monthly and annual to date usage. These totals are saved to two hard disks and hard copies are printed monthly. The Excel worksheet referenced above includes a sheet called Loss Analysis. This section compares each main meter with all delivery meters downstream.