Why should prepared water sample bottles not be rinsed before collecting samples for bacteriological examination?

Prepared water sample bottles for bacteriological examination are specifically designed to ensure accurate and reliable testing results. The presence of sodium thiosulfate crystals in these bottles is significant because their primary role is to neutralize chlorine residuals that may be present in the water sample. Chlorine is commonly used as a disinfectant in municipal water systems, and if it remains in the water sample during testing, it can inhibit the growth of bacteria, leading to inaccurate results.

By not rinsing the sample bottles, the sodium thiosulfate can effectively fulfill its purpose of neutralizing any chlorine, allowing the natural bacterial content of the water to be analyzed without interference. Maintaining the integrity of the sample and ensuring no external contaminants are introduced during the collection process are paramount, but the specific action of sodium thiosulfate is critical for the bacteriological testing environment. The other options do provide various reasons related to sample integrity, but they do not directly address the unique function of sodium thiosulfate in the context of chlorine neutralization.