CELS researchers link climate change and septic systems

KINGSTON, R.I. – September 6, 2016 – A team of researchers from the University of Rhode Island is recommending that state and federal officials rethink the regulations for the installation and management of home septic systems, especially in the coastal zone, in light of research they conducted that demonstrated that warming temperatures and rising sea levels will reduce the effectiveness of conventional septic systems.

The study by doctoral student Jennifer Cooper, Professor Jose Amador and Research Associate George Loomis found that a one-foot increase in the height of the water table due to sea level rise and a 5 degree centigrade increase in air temperature would reduce a septic system’s ability to filter out phosphorous and nitrogen before it reaches the ground water and nominally affect bacteria and carbon removal.

“In conventional septic systems, we rely on the soil to remove bacteria, phosphorous, carbon and nitrogen before treated effluent reaches the groundwater,” said Amador, a professor of soil science. “But if the drainfield is not performing as it should because of climate change, then we may be degrading our groundwater quality.”

The researchers say the issue is of national concern. About one quarter of U.S. households use septic systems to treat their wastewater, and in some areas where municipal sewers are unavailable, septic systems are the only option. In Rhode Island, one-third of households have on-site septic systems.

In an experiment that lasted more than two years, the scientists used a series of mesocosms to simulate the conditions in several types of conventional and alternative septic systems and drainfields. For the first 18 months, the experiment tested the effectiveness of the systems under current climate conditions. As expected, almost all bacteria, phosphorous and carbon were filtered from the wastewater before it reached the groundwater, and between 5 and 12 percent of the nitrogen was removed…[Read more]