Monitoring your water meter is a great way to check whether you still have a leak. You'll generally find the house's meter close to the street. Note down the numbers you see on the meter dial. Come back in an hour to check again and compare. Ensure no one uses any taps or flushes the toilets during this period, and it's best to do this test when no one is home.
If you can't find the source of the leak, look for wall discolouration, bubbling paint, damp locations and mould growth. A musty smell is a red flag when it comes to leak detection.
If you suspect the leak is outside the property, check for usually green sections of lawn or saturated and boggy soil. - MitchellMc
Use a heater blower fan to dry.
Place a piece of blotting paper (you can get some at Officeworks) around the pipe and check the moisture absorption level.