The water main runs from the meter at the curb to your foundation, and in an older La Mesa home that line may be as old as the house. When it starts to leak, the signs are usually the same, a green stripe in the lawn during a dry month, a meter that keeps turning with everything in the house off, pressure that faded everywhere at once, or a bill that jumped when nothing else changed.
Locating matters, because without it someone ends up digging test holes across the yard. Tracing the route, with leak detection in support, helps isolate the area, and the culprit could be a fitting that let go, a section harmed by settling soil or root pressure, or original galvanized that corroded through. If the line has life left, the fix may be a local repair. If it doesn't, the talk turns to replacement, and on a suitable route trenchless methods can pull new line through small openings instead of an open trench through the yard you've spent years on.
A leaking main keeps running through your meter, and the wet ground may take a toll on hardscape and foundations above it. You get the findings in plain English and the options laid out with their real tradeoffs, the choice is yours, and a licensed contractor performs the work when you give the word.