A recent study has shown that septic systems in the U.S. routinely discharge pharmaceuticals, consumer product chemicals and other potentially hazardous substances into the environment. The comprehensive study, published in the journal Environmental Science & Technology, raises health concerns since these chemicals can end up in groundwater and drinking water supplies.
About one in five U.S. households rely on septic systems to process their wastewater. In some places, the number is much higher. On Cape Cod, Massachusetts, for example, 85% of residents use septic systems.
The recent work was a meta-analysis of 20 different studies on septic systems and looked at 45 different contaminants in total including pharmaceuticals, personal care product ingredients, cleaning product ingredients, flame retardants, hormones, and things like caffeine. It turns out that septic systems do a good job of removing some chemicals – such as acetaminophen, caffeine and the alkyphenols used in cleaning products – but are much less effective at removing TCEP, a carcinogenic flame retardant, an anti-epilepsy drug called carbamazepine, and the antibiotic sulfamethoxazole.
In high-density areas where there are lots of homes with their own septic systems, these systems may be the primary source of emerging contaminants in groundwater. This can really be a problem when residents rely on private, shallow groundwater wells for their drinking water (which is pretty common in Massachusetts, Delaware, Florida, Maryland, New Jersey, and New York).
It is important to keep septic systems away from areas that supply local drinking water wells and people need to follow guidelines for maintaining their septic systems to make sure they are in good working order. Of course, avoiding household products with harmful ingredients by switching to safer alternatives can make a real difference.
Photo, posted July 9, 2004, courtesy of Soil Science via Flickr.