| County | Population | Average Household Income | Water Hardness (mg/L) |
| Anderson | 75,129 | $44,650 | 90 |
| Carter | 57,424 | $31,173 | 61 |
| Cumberland | 56,053 | $36,813 | 76 |
| Davidson | 626,681 | $56,084 | 115 |
| DeKalb | 18.723 | $34,863 | 70 |
| Dyer | 38,335 | $36,856 | 76 |
| Hamilton | 336,463 | $45,408 | 94 |
| Jackson | 11,509 | $32,722 | 63 |
| Knox | 432,226 | $46,759 | 92 |
| Madison | 98,294 | $40,178 | 80 |
| Maury | 80,956 | $46,278 | 95 |
| Montgomery | 172,331 | $48,930 | 98 |
| Putnam | 72,321 | $35,185 | 70 |
| Rutherford | 262,604 | $53,770 | 87 |
| Shelby | 927,644 | $44,705 | 71 |
| Sullivan | 156,823 | $39,957 | 59 |
| Sumner | 183,545 | $54,916 | 92 |
| Washington | 336,463 | $41,256 | 60 |
| Williamson | 205,226 | $87,832 | 139 |