Water Supply Line Leak

Last night I was in my basement mechanical room of my relatively new construction house in a rare moment that the HVaC and heat pump water heater were not running. I could hear what I initially thought was low flow water running through the water supply line and just assumed that it was a toilet filling up after a flush but then it kept going.

After verifying that no water was running in the entire house I then closed the quarter turn ball valve on the 1-1/8” incoming copper line and the sound continued. Then I went out to the water meter that’s under a manhole in the front yard and watched the meter and water was slowly flowing through the meter. I then closed the valve going from the meter to the house and the meter showed that no water was flowing. I went back in the mechanical room and the flowing sound was gone. Then I went back to the meter and turned the valve back on and went back to the basement and the flowing sound was back and meter showed it was flowing. So as far as I can tell I have a small leak somewhere between the meter and the foundation wall.

I went back through photos of when the water line was installed by the plumber in 2019 and I have three places where I would guess the leak is at. 1. At a joint where the supply line appears to have been spliced/soldered together, 2. where the line crosses under a concrete knee wall for the wrap around porch, 3. where it enters the main foundation approximately 48” above basement floor.

1. Would be ideal as it’s relatively easy to dig up and cause almost zero collateral damage. 2 and 3. are potential nightmares as it would require dismantling existing wood porch and supporting structure in order to dig. I was very careful when I backfilled and did my best to fill up to the water line level and compact as much as possible under the line and then gentle backfill over the line. The area between the knee wall and foundation was then exposed to many manny months of rain before the front porch and roof were built over it so it should have settled thoroughly long ago. Additionally there is a footer drain to sump under where the water line enters the foundation and I have not heard the sump running randomly and when I have checked it recently during dry spells it was dry. I have no clue when this leak started but I’m trying to dig through my water bills and see if I can see a spike somewhere.

While I seriously hope the leak is at the solder joint I am concerned it might be closer to the foundation wall since I can hear it flowing in the basement but maybe the sound transfers through the pipe really well. I am waiting from a call back from the original plumber to get his take but I’m curious if anyone on Reddit has thoughts or experiences to help me before I start digging.