Survival of pathogens in waste materials, soil, or water, depends on many environmental factors including temperature, pH, organic matter content, moisture, exposure to light, and the presence of other organisms.   Fecal material can be directly deposited, washed into waters by overland runoff, transported through the ground, or discharged to surface waters via sewer lines, pipes, or drainage tiles. Risk of exposure to humans requires:
# Pathogens to survive and be present;
# Pathogens to recreate in surface waters;
# Individuals to come in contact with water for sufficient time, or ingest sufficient volumes of water to receive an infectious dose.
Die-off rates of bacteria in the environment are often exponential, therefore, direct deposition of fecal material into waters generally contribute higher concentrations of pathogens than material that must be transported overland or through the subsurface.