If that natural spring water tastes refreshingly sweet it may not be as pure and healthy as it seems. A recent study conducted by a team of scientists from the University of Waterloo shows that Artificial Sweeteners are a good indicator of contamination by wastewater seeping from a septic sewage system.
The researchers analyzed water samples collected from private groundwater wells in a rural area within the Nottawasaga River Watershed, testing for the presence of four artificial Sweeteners, which if present, would indicate that human wastewater originating from local septic tanks had seeped into the groundwater.
Because artificial sweeteners leave our bodies relatively unchanged and do not get completely removed when wastewater is treated, they serve as an ideal marker for the presence of human wastewater, which typically contains artificial sweeteners in high concentrations.
While the artificial sweeteners are themselves pretty harmless to humans, wastewater can contain harmful contaminants such as viruses, E. Coli, ammonium and nitrate, as well as pharmaceuticals and personal care products that can contain potentially hazardous toxins. Also, it is not known whether artificial sweeteners can be harmful to aquatic life.
For the study, which was recently published in the Journal of Environmental Quality, the researchers tested 59 private drinking water wells. They found that 30% of the wells tested had a least one of the artificial sweeteners present, indicating contamination with human wastewater. It is estimated that between 3-13% of drinking water wells could consist of at least 1% septic wastewater effluent.
The researchers also analyzed groundwater samples seeping from the banks of the Nottawasaga River. They found 32% of the samples had sweeteners present, indicating that groundwater flowing into the Nottawasaga River is impacted to some degree by human effluent from septic wastewater systems.
Septic tanks are a common form of wastewater treatment for homes in rural areas where no municipal sewage system is available. A septic tank separates the solid waste into a chamber where it undergoes treatment by bacteria, after which the liquid effluent seeps through a septic drainage field that breaks down the waste further.
An earlier study conducted by the research group found artificial sweeteners in the Grand River and also in treated drinking water supplied from this source.
"We were not really surprised by the most recent results given what we've found in past studies," said lead author John Spoelstra, an adjunct professor in earth and environmental sciences at Waterloo and a Research Scientist with Environment and Climate Change Canada. "Septic systems are designed to discharge effluent to groundwater as part of the wastewater treatment process. Therefore, contamination of the shallow groundwater is a common problem when it comes to septic systems."
Spoelstra, J., N.D. Senger, S.L. Schiff. (2017) Artificial sweeteners reveal septic system effluent in rural groundwater. Journal of Environmental Quality. doi: 10.2134/jeq2017.06.0233.