Creates a federal Healthy Drinking Water Affordability Assistance Program that gives grants to eligible rural households and small rural facilities to pay for water testing, point-of-use/point-of-entry treatment systems, certified filter components, installation, and maintenance when health contaminants are detected. The program sets eligibility rules (including household income limits and caps on grant amounts), administration and allocation procedures, reporting to Congress, and is authorized at $10 million per year for fiscal years 2026–2030.