Fecal coliforms include bacteria that may or may not originate from feces. Measuring for fecal coliforms reveals the overall contamination of water with E. Coli and other pathogens.
The presence of fecal coliforms does not always mean that feces are present in the water. When they are, pet waste is often a major contributor to fecal coliform populations, especially in urban areas with a large dog populations. Many communities have enacted pooper scooper ordinances to help reduce the amount of waste in their waterways and increase the quality of their water.