Lake Charles Water Hardness & Quality Report (2026)

Lake Charles, Louisiana, the Calcasieu Parish seat in southwest Louisiana — a major petrochemical and LNG export hub on the Calcasieu River — draws its municipal water supply from the Calcasieu River and Lake Charles (a natural riverine lake on the Calcasieu River) via the City of Lake Charles Water Division, treating Calcasieu River water at the Lake Charles Water Treatment Plant serving the metropolitan area. Water hardness in Lake Charles measures 93 mg/L — classified as moderately soft.

Lake Charles' moderately soft supply reflects the southwest Louisiana Gulf Coastal Plain geology of the Calcasieu River watershed. The Calcasieu River drains the Pleistocene Prairie Formation (reddish clay and silt — low carbonate) and the Quaternary marsh and swamp alluvial deposits of southwest Louisiana — a flat, nearly featureless coastal plain underlain by thick Quaternary clays, sands, and silts deposited in the Gulf of Mexico coastal environment. The southwest Louisiana coastal plain is essentially calcium-free — thick clay and quartz sand formations with minimal carbonate content — contrasting with the calcium-rich limestone terrain of Florida or Texas. The result is a moderately soft supply typical of Gulf Coast plain river systems in Louisiana.

With hardness at 93 mg/L, Lake Charles residents experience light to moderate scale accumulation. Faucet aerators and showerheads develop deposits slowly — bi-monthly cleaning with citric acid solution is sufficient. City of Lake Charles Water Division consistently delivers water meeting all Louisiana DEQ and EPA Safe Drinking Water Act requirements.