I found out that I have a water leak under my slab floor. Apparantely the leak is between the shutoff out in the yard and the meter(which is located in the hallway utility closet). I hear water gurgling in my ductwork which is also in the slab.
Called local plumber and he says I'm looking at $1500.00- $1700.00) :( I think I can fix it myself if I knew how to locate the leak without jackhammering extensive amount of floor.