North Carolina rules governing public water systems require records of bacteriological analyses be kept on or near premises for a minimum of how many years?

• A. Three years
• B. Seven years
• C. Ten years
• D. Five years

Answer: (D)

Public water system records of bacteriological analyses must be kept on or near the premises for at least five years. This on-site retention gives operators and inspectors quick access to historical sample results during routine inspections, sanitary surveys, or investigations of any positive tests, and helps show performance trends over a reasonable period. Five years provides a practical balance between having enough past data to assess water quality and not imposing excessive storage. Longer retention isn’t required by North Carolina rules for this purpose, though systems may choose to keep records longer if they wish.