An inventory of public water-supply systems in Tennessee in 1995 indicated that 530 public water-supply systems supplied water to 4.42 million people, or 84 percent of Tennessee's population. Public-supply water withdrawals totaled 779 million gallons per day, 64 percent (500 million gallons per day) of which was from surface-water sources. All of the surface-water withdrawals for public-water supply took place within the Tennessee (279 million gallons per day) and the Ohio (221 million gallons per day) hydrologic regions. Ground-water withdrawals statewide accounted for 36 percent (279 million gallons per day) of the total public-supply water withdrawal. Ground water is the sole source of public-supply water in the Lower Mississippi hydrologic region of western Tennessee. Public water-supply systems in western Tennessee withdrew 216 million gallons per day, or 77 percent, of the 279 million gallons per day of ground water withdrawn for public supply statewide.