What are the acceptable limits for fecal coliform in treated effluent?

The acceptable limit for fecal coliform in treated effluent for recreational waters is typically less than 200 CFU/100 mL. This standard is crucial because fecal coliform bacteria are indicators of potential contamination by fecal matter, which can introduce pathogens harmful to human health. When effluent is distributed into recreational waters where people swim or engage in water activities, maintaining this strict limit helps to ensure safety and protect public health.

Maintaining levels below this threshold minimizes the risk of waterborne diseases that could arise from volumes of fecal contamination that exceed the acceptable limits. Regulatory bodies often establish these standards based on health studies linking fecal coliform concentrations with the incidence of illness in recreational water users. This threshold reflects an essential balance between water pollution control measures and public health considerations.

Other options suggest limits that are either appropriate for different uses of water or exceed the limits set for recreational waters. For instance, drinking water standards are much stricter, since human consumption requires almost no tolerance for fecal contamination.