If you live in Michigan, you may want to invest in a home water filtration set, just to be safe. A recent study has uncovered that 64 rivers in the Great Lake State have been contaminated with human fecal bacteria. The source of the contamination was identified as a critical error in septic tank design and, unfortunately, experts think the problem is more widespread.

For the study, which is the largest of its kind to this date, researchers from Michigan State University used source-tracking markers to sample water from 64 rivers that drain 84 percent of Michigan’s Lower Peninsula. The markers allowed the scientists to identify the presence of Escherichia coli ( E.coli ) and Bacteroides thetaiotaomicron ( B-theta ), two bacteria associated with human feces. The markers also tracked down the source of contamination. Results revealed that all of the rivers tested positive for these fecal bacteria, but the concentration of the pathogens increased as the number of nearby septic tanks went up.

Critical Error

For years, scientists believed that soil could act as a natural filter for human feces, Phys.org reported. Based on this theory, many septic tanks have been built based on the discharge-to-soil method, which in simplest terms is a hole in the ground beneath the toilet (such as an outhouse). The latest findings, however, disprove this idea.

"All along, we have presumed that on-site wastewater disposal systems, such as septic tanks, were working," said Joan Rose, Homer Nowlin Chair in water research, to Phys.org. "But in this study, sample after sample, bacterial concentrations were highest where there were higher numbers of septic systems in the watershed area."

Unfortunately, the team believes it’s likely that this problem isn’t restricted to Michigan. The team predicts to see similar readings in Florida, South Carolina, and other resort areas near lakes across America.

Time To Redesign

Feces contamination, particularly E.coli contamination in drinking water, can lead to serious complications. According to the U.S. Environmental Protection Agency, drinking contaminated water can lead to side effects such as severe or/and bloody diarrhea, abdominal cramps. In those who are very young or very old, the infection can cause a condition known as hemolytic uremic syndrome. This condition occurs when the red blood cells are destroyed and the kidneys fail.

One of the most serious E.coli outbreaks traced to drinking water occurred near Albany, N.Y. in 1999. There were a total of 781 suspected and reported cases of E.coli infection, 65 individuals were hospitalized, 11 children developed hemolytic uremic syndrome, and two individuals died. Rose hopes that her research will help further our understanding of how our manipulation of the environment can affect our health.

Source: Rose JB, Verhougstraete MPP, Martin SL, Kendall AD, Hyndman DW. Linking fecal bacteria in rivers to landscape, geochemical, and hydrologic factors and sources at the basin scale. PNAS. 2015.