BDL stands for which?

• A. Below detection limit
• B. Below decision limit
• C. Below disinfection limit
• D. Below distribution limit

Answer: (A)

BDL means BELOW DETECTION LIMIT. In lab testing, it indicates the concentration is too low to be measured reliably by the method or instrument used—the signal is not distinguishable from background noise, so the result is reported as not detected (BDL) rather than given as a numeric value. This reflects the limits of the analytical method, not that the substance is proven absent. The other phrases aren’t standard for reporting a non-detect: “below decision limit” refers to a regulatory cutoff for decision-making rather than the instrument’s detection capability, and “below disinfection limit” or “below distribution limit” aren’t typical terms in water analysis.