Records of turbidity analysis must be kept for at least how many years?

• A. 3 yrs
• B. 5 yrs
• C. 7 yrs
• D. 10 yrs

Answer: (B)

Records of turbidity analysis are kept for a period long enough to show how the treatment system performs over time and to support regulatory oversight. Turbidity reflects how well the system is removing particulates and can indicate changes in treatment effectiveness or source water quality. Having a five-year record provides a sufficient historical trail for audits, investigations, and trend analysis, helping verify that the system consistently meets turbidity limits.

In this context, the minimum retention is five years. Shorter retention would limit the ability to review historical performance, while longer retention isn’t the required standard for turbidity data. Keeping turbidity records for five years also pairs well with other long-term water quality data to understand how various factors influence treatment performance over time.