How many colony-forming units per milliliter (CFU/mL) is the acceptable limit for heterotrophic plate count in reagent grade water?

The acceptable limit for heterotrophic plate count (HPC) in reagent grade water is set at 500 CFU/mL. This standard is important because HPC testing is a quality control measure used to assess the microbiological quality of water. Reagent grade water is often used in scientific and analytical applications, where purity is crucial.

A result of 500 CFU/mL indicates a threshold for the presence of heterotrophic microorganisms, which can serve as an indicator of the general bacterial population in the water. Levels above this limit may suggest potential contamination and could compromise experimental results or product quality. This standard helps ensure that the water remains suitable for sensitive laboratory work and other applications where high purity is essential.