What is the purpose of Sodium Thiosulfate in BAC-T bottles?

Sodium thiosulfate serves a crucial role in BAC-T (bacteriological) bottles as a chlorine neutralizer. When water samples are collected for microbiological testing, any residual chlorine present could inhibit the growth of bacteria, leading to false negative results. By adding sodium thiosulfate to the sample, the chlorine is effectively neutralized, allowing for accurate detection of any bacteria present in the water. This is essential for ensuring that water quality assessments provide reliable results regarding microbial contamination.

The other options do not align with the purpose of sodium thiosulfate in bacteriological testing. Enhancing chlorine levels, lowering water temperature, or increasing water pH do not correctly describe its function in this context, as the objective is specifically to eliminate the effects of chlorine from the sample to ensure valid microbiological analysis.