It’s not unusual to find a water meter registering flow even though all the taps are off.
This can be attributed to your irrigation systems solenoid valves leaking. Unfortunately it is not always easy to see if the solenoid values are leaking, as the water can exit the irrigation zone in an area that is not visible, and even small leaks over time become big bills.
The best way to check for leaking values, is to first determine if your water meter registers flow when all the taps are off. If that is the case, remove the threaded fitting directly after each solenoid valve or soon thereafter and check for water passing the closed solenoid valves. As these solenoid valves are often covered in dirt or roots take care when clearing the area around the values so as not to damage the pipes and electric cables.
When you find a leaking value you can try servicing it by taking the valve lid off and gently cleaning the diaphragm with soapy water, if that does not work it may be time to replace it, or have an irrigation specialist replace it for you.
Water Rhapsody Atlantic