Bunnings sell cheap Aqua Systems Two Dial Electronic Tap timers that allow you to set a repeating timed/duration watering system that you connect to a standard hose fitting. The problem is this does not factor in watering restriction guidelines, rain events or variations in the weather.
One of my goals is to hack an Aqua Systems Two Dial Electronic tap timer and replace its circuitry with an Arduino micro controlled that is connected to the web/online schedule.
Opening the timer reveals a simple 3v IC, 3V motor, torque increasing plastic gears, flexing circuit breaker connected to a gear and a rotating ball joint to allow/ block water flow.
Each hacked unit will communicate with a single house raspberry pi that handles the schedules etc