The water main is the line that runs from the meter at the street to your house, and most people never think about it until it starts to leak. The common signs are a wet patch in the yard that never dries, a meter spinning with every fixture off, pressure that dropped house wide all at once, or a water bill that jumped way up. Sometimes the water shows up out front instead, seeping up through the parkway or the driveway seam.
The fix depends on what failed and where. Locating work can help narrow down where it failed, whether a split at a fitting, a section pinched by root pressure or shifting ground, a corroded stretch finally through, and the fix gets scoped to the finding. Sometimes that means a repair right at the failure instead of trenching the full length of the line. Sometimes, with older galvanized or a line that has failed before, replacement is the right answer, and where the route fits, a trenchless approach can pull a new line through with limited excavation instead of an open trench across everything you've planted.
The leak keeps running through your meter every day, soaked ground can wear on whatever sits above it, and the pressure can keep dropping. The fix follows what the locating shows, with a licensed contractor performing the work and every option laid out in plain English first. It's your line and your yard, so the decision is yours.