TN HB1983

Establishes a maximum hardwater standard of 180 mg/L (measured as calcium carbonate equivalents) for public water systems in Tennessee, effective July 1, 2026

Compliance is required only for public water systems that receive state funds for system upgrades of $25,000 or more on or after July 1, 2026; systems not receiving such funds are grandfathered and exempt

Provides a seasonal runoff exemption allowing temporary exceedances up to 120 days per year without prior approval, with systems required to return to compliance within 90 days after the runoff period ends

Requires systems claiming the seasonal runoff exemption to notify the department within 10 business days, provide documentation, and submit a remediation plan if requested

Mandates hardwater monitoring per department protocols and inclusion of results in annual water quality reports