The Environmental Working Group (EWG) reported the presence of various chemicals in drinking water provided by water supply utilities across the United States and advocates aspirational targets that are often well below the federal and state standards that have been established to ensure the public health.
It should be noted that much of the data in this report came from only a small number of samples taken by utilities in 2015 regarding chemicals that in many cases are not even regulated by the government as it relates to drinking water quality standards.
Four of the chemicals identified in the report are Hexavalent Chromium, Perfluorinated compounds, Radium, and Total Trihalomethanes.
Hexavalent Chromium: The 12 WASD samples the study refers to from 2015 ranged from .03 parts per billion to .17 parts per billion. There currently is no drinking water standard for this phase of chromium, but the EPA drinking water standard for total chromium, which includes hexavalent chromium, is 100 parts per billion. The California drinking water standard for hexavalent chromium is 10 parts per billion, significantly higher than any of the Miami-Dade County test results.
Perfluorinated compounds (PFAS): A total of 7 samples were taken from water entering WASD’s largest water treatment plants in 2015. Six of the sample results showed no detections. One sample showed a concentration of .043 parts per billion. A subsequent sample at the same plant showed no detection. The EPA health advisory level for this family of chemicals is currently .070 parts per billion, almost double the concentration found in the one sample that had a detectable result.
While there is no drinking water standard for these compounds, the EPA is currently developing a plan for adopting a drinking water standard based upon interpretation of health data. WASD - in collaboration with Miami-Dade County Regulatory and Economic Resources (RER)/DERM - is undertaking additional analysis of these compounds both in drinking water and ground water.
Radium: The EPA drinking water standard is 5 picocuries per liter. Of the four samples tested (2 in 2011 and 2 in 2014), one sample showed no detection and the other 3 samples ranged from .15 to .60 picocuries per liter, a small fraction of the established drinking water standard. The EWG, however, applied a health safety standard of 0 picocuries per liter, so any detection exceeded their standard.
Total Trihalomethanes: Since trihalomethanes, a family of chemicals that result from disinfecting water with chlorine, were identified as representing a health risk in the 1970s, most utilities, including WASD, have modified their treatment processes to reduce the formation of these compounds. The current EPA drinking water standard for trihalomethanes is 80 parts per billion. These chemicals are tested frequently, and the reported average of quarterly sampling between 2011 and 2015 in Miami-Dade’s water is 43.5 parts per billion, about half of the EPA drinking water standard. However, EWG applies the health goal of .8 parts per billion to these chemicals.
Miami-Dade County’s Board of County Commissioners has enacted restrictions regarding types of businesses/industries that can locate near a well-field as an added safeguard to prevent potential negative impacts to the Biscayne Aquifer.
It is the priority of the Miami-Dade Water and Sewer Department to provide safe, reliable service to its customers. For additional information about Department services and programs, visit the WASD website.