Concrete spotting on garage floor

[Codenforcer]

So I’ve been in this house about 12yrs now and have always thought something was strange about these spots on the floor on one side of the garage. It was built in 83 and is a brick home, the side of the garage it is on is where the water supply comes up and into the side of the garage. To me it seems like moisture from the ground underneath but I’m no expert on concrete. This is in south Texas. I honestly can’t say it’s got much bigger over the years but it does seem to differentiate is contrast with the humidity. What do you guys think? Something to worry about? The floor is really sandy, not a very good quality concrete, rolling the floor jack around will cause it to create loose fine pieces off the top.

 

[PWC Repair]

Tape down a 2 ft square of plastic like a trash bag. Leave it a day, then peel it up and see if there is water collecting under it. Could very well be a leaky pipe.

 

[Codenforcer]

Tried the covering trick, it collects moisture. My main water supply comes in from outside the brick about 6’ away. It’s copper pipe that comes up from the ground and not through the foundation. The water heads up inside the wall to the attic where it’s split from there. If the main pipe is coming from the opposite side from the meter I don’t see why I wouldn’t have any moisture closer to where the pipe comes from under the ground. Any suggestions on isolating this problem?

 

[Shea]

You may have a very small leak under ground where the pipe comes up. If the possible leak is on the house side of the meter, turn off all running water in the house and check the meter to see if it is running at all.

 

[zeeway]

...or underground spring.