Caffeine and pharmaceuticals as indicators of waste water contamination in wells

Abstract

The presence of caffeine or human pharmaceuticals in ground water with elevated nitrate concentrations can provide a clear, unambiguous indication that domestic waste water is a source of some of the nitrate. Water from domestic, public supply, and monitoring wells in three communities near Reno, Nevada, was sampled to test if caffeine or pharmaceuticals are common, persistent, and mobile enough in the environment that they can be detected in nitrate-contaminated ground water and, thus, can be useful indicators of recharge from domestic waste water. Results of this study indicate that these compounds can be used as indicators of recharge from domestic waste water, although their usefulness is limited because caffeine is apparently nonconservative and the presence of prescription pharmaceuticals is unpredictable. The absence of caffeine or pharmaceuticals in ground water with elevated nitrate concentrations does not demonstrate that the aquifer is free of waste water contamination. Caffeine was detected in ground water samples at concentrations up to 0.23 μg/L. The human pharmaceuticals chlorpropamide, phensuximide, and carbamazepine also were detected in some samples.