Sodium thiosulfate is added to bacteriological sample bottles.

Sodium thiosulfate is added to bacteriological sample bottles.

• A. Only for certain samples
• B. True
• C. Not added to bottles
• D. False

Answer: (B)

Sodium thiosulfate is used to neutralize residual disinfectants, especially chlorine, in water samples collected for bacterial testing. Chlorine can continue to kill or inhibit bacteria after the sample is drawn, which would skew results. Including thiosulfate in bacteriological bottles (or using bottles pretreated with it) stops that post-collection disinfection, so the test reflects the true bacterial content at the time of collection. That’s why the statement is true. It’s specifically used for bacteriological samples in chlorinated systems; if the water isn’t disinfected, thiosulfate isn’t needed, but standard practice for chlorinated systems is to have it in the bottles.

Sodium thiosulfate is used to neutralize residual disinfectants, especially chlorine, in water samples collected for bacterial testing. Chlorine can continue to kill or inhibit bacteria after the sample is drawn, which would skew results. Including thiosulfate in bacteriological bottles (or using bottles pretreated with it) stops that post-collection disinfection, so the test reflects the true bacterial content at the time of collection. That’s why the statement is true. It’s specifically used for bacteriological samples in chlorinated systems; if the water isn’t disinfected, thiosulfate isn’t needed, but standard practice for chlorinated systems is to have it in the bottles.