Septic Tanks Aren’t Keeping Poo out of Rivers, Lakes

Posted in: United States Water News, Water Contamination
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Water pollution in river. Photo Credit: Thinkstock

Article courtesy of Brett Smith | August 3, 2015 | RedOrbit | Shared as educational material

Septic tanks have long been thought of as a way to keep human waste out of the environment in areas where sewer lines are inaccessible.

But now, a new study in the Proceedings of the National Academy of Sciences journal has traced fecal matter found in Michigan’s lakes and rivers to septic systems.

“All along, we have presumed that on-site wastewater disposal systems, such as septic tanks, were working,” said study author Joan Rose, a water quality expert at Michigan State University. “But in this study, sample after sample, bacterial concentrations were highest where there were higher numbers of septic systems in the watershed area.”

Not much better than a hole in the ground

An upgrade from a simple hole-in-the-ground outhouse, septic systems have been thought of as an effective means for controlling human waste. However, this new study somewhat dispels that notion.

“For years we have been seeing the effects of fecal pollution, but we haven’t known where it is coming from,” Rose said. “Pollution sources scattered in an area – called non-point – have historically been a significant challenge in managing water quality.”

In the study, researchers used something called a source-tracking marker to collect samples from 64 river systems in Michigan in search of E. coli and the human fecal bacteria, B-theta. Developments in source-tracking enable water researchers to locate the source of non-point contaminants better than ever before, and this state-of-the-art technology allow the study team to trace bacteria right back to septic systems.

“This study has important implications on the understanding of relationships between land use, water quality, and human health as we go forward,” Rose said. “Better methods will improve management decisions for locating, constructing, and maintaining on-site wastewater treatment systems. It’s financially imperative that we get it right.”

Rose and the other study authors said more needs to be done in to prevent surface water contamination via septic tanks. They noted the Environmental Protection Agency’s latest survey for capital improvement called for the investment of nearly $300 billion over the next two decades on wastewater and stormwater infrastructure in order to reach the Clean Water Act targets for swimmable and fishable waters.

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