What monthly test should be conducted to assess bacterial contamination in reagent grade water?

Heterotrophic Plate Count (HPC) is the correct choice for assessing bacterial contamination in reagent grade water. This test evaluates the presence of a broad spectrum of heterotrophic bacteria that can exist in water, helping to identify general microbial quality. In environments where water purity is critical, such as laboratories, the presence of these microorganisms can indicate potential contamination that might affect experimental results or the quality of reagents.

Unlike pH testing, which measures the acidity or alkalinity of water, or chlorine level testing, which typically assesses disinfection effectiveness, these tests do not provide direct information about bacterial contamination. Conductivity testing measures the ion concentration in water and gives insights into the presence of dissolved solids but does not specifically indicate microbial presence. Therefore, HPC stands out as the most relevant monthly test for evaluating bacterial contamination, making it essential for maintaining high-quality standards in reagent grade water.