Why is sodium thiosulfate added to bacteria water sampling bottles?

Sodium thiosulfate is used in bacteria water sampling bottles specifically to neutralize any chlorine present in the water sample. Chlorine is commonly used as a disinfectant in municipal water supplies, but it can also be harmful to the bacteria that are being studied. If chlorine is still active in the sample when it’s collected, it could kill off the target bacteria, leading to inaccurate results in microbiological testing. By adding sodium thiosulfate, any residual chlorine is neutralized, allowing for a more accurate representation of the bacterial population in the water sample. This step is essential for ensuring that laboratory results reflect the true microbial content of the sample, which is crucial in assessing water quality and safety.