Water Authorities - As introduced, establishes that public water systems have a maximum allowable hardwater level of 180 mg/L, measured as calcium carbonate equivalents; creates compliance and reporting requirements; exempts measurements that exceed the limit due to seasonal runoff in certain circumstances. - Amends TCA Title 68, Chapter 221, Part 7.

HB 1983 sets a maximum hardwater level of 180 mg/L (measured as calcium carbonate) for public water systems in Tennessee. It requires systems receiving state funds for major upgrades (costing $25,000+) after July 1, 2026, to comply with this standard upon completion. Systems affected by seasonal runoff (e.g., snowmelt) may temporarily exceed the limit if they notify authorities within 10 days, provide documentation, and submit a remediation plan - though exemptions cannot exceed 120 days annually without approval. All affected systems must monitor and report hardwater levels in annual water quality reports. This bill amends Tennessee Code Annotated, Title 68, Chapter 221, Part 7, and takes effect July 1, 2026.