Total coliform bacteria are commonly found in the environment and are generally harmless while fecal coliform bacteria are a sub-group of total coliform bacteria. The presence of fecal coliform in a drinking water sample often indicates recent fecal contamination, meaning that there is a greater risk that pathogens are present than if only total coliform bacteria is detected. The presence of fecal contamination in aquatic environments is an indicator that a potential health risk exists for individuals exposed to this water. Multiple tube fermentation technique is often used for the determination of total and fecal coliforms.