Most leaks here are noticed on the water bill rather than seen, because they happen under floors and inside walls.
A test you can do in a minute
Turn off every tap and anything that uses water, then look at the meter. If it is still moving, water is going somewhere it should not.
Why the usual clues are less reliable here
Normally a soft or unusually green patch of ground points to an underground leak. On James Island the ground is often damp anyway, so that clue is much less dependable. It is one of the reasons we use listening equipment and thermal imaging rather than looking for surface signs.
Where they usually turn out to be
In older homes, at corroded galvanised sections and joints that have been repaired before. In newer ones, at fittings and connectors rather than the pipe. Outdoor spigots are common in both, and they often leak into the wall rather than where you would see it.
Why it is worth acting quickly
A slow leak becomes flooring, cabinets and framing fairly quickly. In our humidity, and under a raised house, it also encourages rot — and that is a much bigger repair than the pipe that caused it.