Marietta Water Hardness & Quality Report (2026)

Marietta, Georgia, the Cobb County seat northwest of Atlanta — a major Atlanta suburb and the largest city in Cobb County, historically significant as the site of the Kennesaw Mountain National Battlefield Park and the childhood home of Margaret Mitchell (Gone with the Wind) — draws its municipal water supply from the Chattahoochee River via the City of Marietta Water Works, treating Chattahoochee River water for the Marietta area. Water hardness in Marietta measures 148 mg/L — classified as moderately hard.

Marietta's moderate hardness reflects the Chattahoochee River's Georgia Piedmont watershed character. The Chattahoochee River above Marietta (from Lake Lanier at Gainesville) drains: the Blue Ridge Province (Dahlonega Gold Belt Cambrian–Ordovician Tallulah Falls Formation phyllite, schist, and granulite — moderate calcareous content from calcareous schist horizons); the Piedmont crystalline belt (Precambrian Grenville-age Henderson Gneiss, Milledgeville Gneiss — calcium-poor crystalline terrain); and the Brevard Zone (a calcareous mylonite zone at the Blue Ridge–Piedmont boundary). The Lake Lanier reservoir retention time allows moderate calcareous equilibration, contributing to the moderate 148 mg/L at Marietta.

At 148 mg/L, Marietta residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. City of Marietta Water Works consistently delivers water meeting all Georgia EPD and EPA Safe Drinking Water Act requirements.