A septic system is considered to be “failing” when it fails to treat and distribute wastewater effectively and fails to prevent biological and nutrient contamination of your drinking water well and nearby lakes and streams. A septic system failure causes untreated sewage to be released and transported to where it shouldn’t be. Failure may cause sewage to rise to the surface of the ground around the tank or the drain field or to back up in pipes in the building. The sewage could also find its way into groundwater, surface water, or marine water without seeing it. The sewage carries pathogens and other dangerous contaminants. Exposure to these pathogens and contaminants can make people and animals sick. They can also contaminate water sources and make them unsafe for drinking, swimming, and agricultural uses.