I live in South Mississippi and have lived in my home with a slab foundation for about 20 years. I have never had a problem with the foundation and the ground is mostly red clay. We do have a septic system which was replaced about 2 years ago with an aerobic system that drains into the woods about 50 yards away. About a month ago I noticed water standing next to the foundation (slab foundation). I dug around it and it filled up with water. There is a faucet right there that has leaked at the faucet but I can turn it off enough not to leak. I've monitored the water meter and there is no leak coming into the house. I dug a small trench to get the water to run away from the foundation. The water does not smell and looks clean, not cloudy or grayish. The man with the water company in our community said it is probably a spring and will dry up on its own. When they installed the new septic system they hit at least 2 other springs in the yard within about 30 feet of this area. I'm just concerned that maybe the water from the bathroom sink or tub is causing this leak. They are both right where this water is showing up. I even took green food dye and put it in water from the sink, bathtub and toilet but nothing showed up outside. I let the water run yesterday for a while with no change in the water level. But when I looked this morning the water was up. Of course I had been digging in the area so that may be why the water has increased. The water level never gets very high and stays about the same except for this morning.
How does the clean water supplied by your utility company differ from natural spring water? Where I live, tap water contains chlorine and chelating agents, and natural spring water contains none of these. Your water company will be able to tell you how to chemically test for tap water vs. spring water.