Which is a required step in collecting a routine distribution sample for bacteriological testing?

The correct answer is the use of an approved, sterile sample container. This step is crucial in bacteriological testing because the integrity of the sample is essential for accurate analysis. Using a sterile container prevents contamination that could lead to false positives or inaccurate results. Bacteriological testing aims to identify the presence of harmful microorganisms in water, and any contamination during the sampling process would compromise the reliability of the test findings.

While sampling at different times of the day may provide a broader understanding of water quality variations, it is not a required step for routine sampling. Heating the water can kill the bacteria, which would defeat the purpose of testing for their presence. Using non-sterile containers is contrary to the requirements for bacteriological sampling, as these would likely introduce contaminants that could skew the analysis. Therefore, ensuring the use of an approved, sterile sample container is vital for obtaining valid and useful test results.