Though no study has examined comparative water quality of onsite and centralized systems as we have done here, a few studies have examined steroids and other contaminants of emerging concern in onsite systems. Standley et al. (2008) documented the presences of endogenous hormones and pharmaceuticals in surface waters fed by aquifers receiving discharge from onsite septic treatment plants. E2 and progesterone were detected in a lower residential density pond in concentrations of 2.2 and 0.73 ng L1.