A leak of this nature usually begins when a home is built on a cement foundation. Slab leak detection can be difficult if you know what you’re looking for.  You could have a slab leak if you hear running water when water should not be running, or if your water bill is unusually high. Big signs include mildew, moisture, or warm spots on the floors of your carpet and cracks in walls or floors. It’s also highly possible you have a leak in your slab if your neighbor does as well, or if you’ve had them before. You will need to hire a plumber to determine where the leak is coming from. The sooner a slab leak is detected, the better because the longer you wait, the worse the problem gets, the more damage that’s caused and the more costly it is to repair.