Building home on slab foundation on lot above natural spring
Before the home was built, there should have been site and soil surveys done.  The builder use the results of this surveys, to determine how to properly construct the foundation for the building. Assuming these surveys were done, and the engineer designed an appropriate foundation. There should be no danger to the structure.  

However, if the water was not taken into consideration, then it could pose a risk to the home. 

You should verify that all the proper planning was done, and that the water was considered in the building planning.