According to the regulations, how many fecal coliform values can a sample exceed over a 30-day period?

The correct answer reflects the regulatory standard set for fecal coliform bacteria concentrations in wastewater samples. Regulations often specify that for a given period—such as a 30-day period—there is an allowable maximum average of fecal coliform bacteria. The value of 25 fecal coliforms per 100 milliliters is a common threshold established to ensure that treated wastewater meets health and safety standards, as fecal coliforms are indicators of potential contamination by pathogens.

Exceeding this concentration can indicate a failure in the treatment process or a risk to public health and the environment. The regulatory limits are established based on the understanding of acceptable risk levels associated with wastewater reuse or discharge. Therefore, adherence to this limit is crucial for compliance with environmental regulations and for protecting water quality.