Following the first bacteriological water sampling, the second sample should measure which parameters?

• A. Temperature and Turbidity
• B. pH and chlorine/bromine residual
• C. Conductivity and Salinity
• D. Hardness and Alkalinity

Answer: (B)

Disinfection effectiveness and sample integrity drive the need for the second bacteriological sample to measure pH and chlorine/bromine residual. The pH level affects how well the disinfectant works—chlorine activity changes with pH, and the stability of the residual is tied to the water’s chemistry. The chlorine or bromine residual shows that an adequate disinfectant level remains in the water, helping you interpret the bacteriological results and ensuring the sample hasn’t degraded or been exposed to insufficient disinfection before analysis. Other parameters like temperature, turbidity, conductivity, salinity, hardness, or alkalinity don’t provide the same direct information about disinfection status or bacteriological interpretation in this testing context.