Without preservatives, a fecal coliform sample can wait to be tested for how many hours?

• A. 2 hours
• B. 4 hours
• C. 6 hours
• D. 8 hours

Answer: (B)

In microbiological water testing, especially for fecal coliform, it is crucial to analyze samples as quickly as possible to ensure the accuracy of results. Generally, without preservatives, a fecal coliform sample should be tested within a maximum of four hours after collection. This time frame is established to minimize the risk of changes in the microbial population that could occur as a sample sits, such as the growth of non-target organisms or the die-off of fecal coliforms.

Delaying beyond four hours can lead to misleading results, such as artificially low counts due to nutrient depletion or changes in environmental conditions which can affect the viability of the bacteria being tested. Therefore, adhering to the four-hour guideline is vital for reliable and valid test results in water quality monitoring.