Pharmaceuticals and other emerging contaminants in source and finished drinking water

The drinking water and wastewater cycles are integrally linked. Chemicals that are present in household wastewater may be sufficiently mobile and persistent to survive on-site or municipal wastewater treatment and post-discharge environmental processes. Such compounds have the potential to reach surface and ground waters. To determine which wastewater chemicals persist through drinking water treatment, a joint USEPA / USGS study examined source and finished waters for nine drinking water treatment plants from across the United States known to be impacted by wastewater. All water samples were analyzed for 84 different emerging contaminants, including 24 pharmaceuticals, at sub-µg/L levels. The sample collection was designed to account for residence time within the plant in order to match waters before and after treatment. The investigated utilities used varying source waters (surface or ground water), disinfectants (chlorine, chlorine dioxide, chloramine, ozone or UV), and produced different volumes of treated water per day (2.3 to 200 mgd). Thirty-five chemicals were detected at least once, with 28 chemicals detected in the source waters and 23 chemicals detected in the finished waters. The greatest number of chemicals detected in a single source water sample was 15; the greatest number detected in a single finished water was 11. The results from those sites that used more advanced treatment (granular activated carbon adsorption, ozonation or UV irradiation) showed greater removal percentages.

Disclaimer: Although this work was reviewed and approved by the USEPA, it may not necessarily reflect official Agency policy.