After a routine sample tests positive for total coliforms, which analyses are required?

After a routine sample tests positive for total coliforms, which analyses are required?

• A. Fecal coliforms and E. Coli
• B. Repeat coliform test and fecal coliforms
• C. E. Coli
• D. Fecal coliforms

Answer: (A)

When total coliforms appear in a routine sample, you’re not just confirming a general microbiological presence—you’re checking for possible fecal contamination. To determine whether fecal matter is actually entering the water, you perform confirmatory analyses for fecal coliforms and for E. coli. Fecal coliforms indicate fecal contamination in general, while E. coli is a more specific and recent indicator of fecal pollution. Testing both provides a clearer determination of public health risk and guides the necessary actions. The other options don’t provide this direct confirmation of fecal contamination, since one test alone (or focusing only on repeat testing) isn’t as definitive as testing for both fecal coliforms and E. coli.

When total coliforms appear in a routine sample, you’re not just confirming a general microbiological presence—you’re checking for possible fecal contamination. To determine whether fecal matter is actually entering the water, you perform confirmatory analyses for fecal coliforms and for E. coli. Fecal coliforms indicate fecal contamination in general, while E. coli is a more specific and recent indicator of fecal pollution. Testing both provides a clearer determination of public health risk and guides the necessary actions. The other options don’t provide this direct confirmation of fecal contamination, since one test alone (or focusing only on repeat testing) isn’t as definitive as testing for both fecal coliforms and E. coli.