Coliform bacteria in the water -- what does it mean? Published March 1, 2011 81st Aerospace Medicine Squadron KEESLER AFB, Miss. -- Feb. 21, Keesler was ordered by the State of Mississippi to issue a boil-water notice due to a water sample taken from one specific location within the base water system testing positive for coliform bacteria. According to Lt. Col. Brian Casleton, 81st Aerospace Medicine Squadron commander, and Lt. Col. (Dr.) Paul Nelson, 81st AMDS chief of aerospace medicine, the presence of coliform bacteria in drinking water may indicate the possibility of a disease-causing organism in the water. While Keesler's water chlorine levels consistently have been normal, this low level of bacteria indicated a possible contamination of the water source. "Line and medical commanders share a responsibility to ensure that Keesler water is safe to consume," they explained. "We maintain a rigorous testing and surveillance system to ensure our water is safe and in compliance with all local, state and federal laws." Human health hazards Low levels of coliform bacteria in water are typically not considered harmful, but may indicate a higher risk of disease-causing pathogens being present in the water. Public health authorities continue to monitor the health of the base population, and have seen no significant or persistent elevations in illnesses associated with food or water. However, in accordance with state law, they agree with the recommendation to boil drinking water until this issue is resolved. Officials added, "Keesler leadership is working with state authorities to ensure base water is completely safe prior to removing the boil water notice." They stressed Keesler's water is safe for routine activities including bathing, hand-washing, brushing teeth and washing clothes. Excerpt from Environmental Protection Agency 1989 Total Coliform Rule The TCR requires all public water systems to monitor for the presence of total coliforms in the distribution system. Total coliforms are a group of closely related bacteria that are (with few exceptions) not harmful to humans. Because total coliforms are common inhabitants of ambient water and may be injured by environmental stresses (e.g., lack of nutrients) and water treatment (e.g., chlorine disinfection) in a manner similar to most bacterial pathogens and many viral enteric pathogens, EPA considers them a useful indicator of these pathogens. More important, for drinking water, total coliforms are used to determine the adequacy of water treatment and the integrity of the distribution system. The absence of total coliforms in the distribution system minimizes the likelihood that fecal pathogens are present. Thus, total coliforms are used to determine the vulnerability of a system to fecal contamination. The TCR requires systems to monitor for total coliforms at a frequency proportional to the number of people served. If any sample tests positive for total coliforms, the system must perform additional tests.