Opelousas Water Hardness & Quality Report (2026)

Opelousas, Louisiana, in Saint Landry Parish — the Saint Landry Parish seat adjacent to Washington and Eunice in the Cajun heartland of south-central Louisiana, known as the Zydeco Capital of the World — receives its municipal water from the Opelousas Water Division, drawing from the Bayou Teche and Bayou Courtableau (Saint Landry Parish) through the Opelousas treatment plant.

The moderately hard 132.5 mg/L hardness and TDS of 313.9 mg/L reflect the south-central Louisiana Bayou Teche drainage basin's calcareous character. The Bayou Teche at Saint Landry Parish drains the Mississippi Embayment — Quaternary Red River alluvial deposits (calcareous from upstream Cretaceous-Eocene Louisiana carbonate), Eocene Wilcox Group calcareous sand (moderate solubility), and Miocene Catahoula Formation (calcareous sand-clay). The cumulative Eocene-Miocene calcareous Embayment loading produces the moderately hard south-central Louisiana supply.

At 132.5 mg/L, Opelousas' water is moderately hard — scale builds in kettles and appliances over months, dishwashers benefit from rinse aid, and faucet aerators need periodic cleaning. Quarterly descaling is appropriate. The PFAS level of 11.8 ppt is very elevated and warrants a certified reverse osmosis drinking water filter — the Saint Landry Parish south Louisiana industrial corridor (Opelousas chemical plant complex), the Bayou Teche agricultural watershed PFAS input, and the south Louisiana PFAS industrial complex contribute to Opelousas' very elevated readings.