An alternative solution is to measure the pressure drop when irrigation valves are opened. When calibrated with the utility company water meter, this can give a good indication of irrigation times and irrigation water volume.
The following is a quick setup to accomplish this, but not intended for permanent use as the power consumption is such that a 6V lantern battery lasts only 6 days.
Three main components are needed: an Arduino Uno board, an Adafruit data logger shield, and a 200 PSI pressure transducer (Eyourlife Universal 200PSI Pressure Transducer Sender Solenoid for Oil Fuel Gas Air Water, $21 @ Amazon.com).
See for transducer also: http://www.vanderleevineyard.com/1/post/2015/03/vinduino-water-pressure-meter.html
The pressure transducer replaces the PSI gauge before the main valve of the irrigation system.
The programming code is available at Github:
This can cause incomplete watering of our lawn due to low pressure, so we'll adjust the sprinkler timer to start later.