Chromium is a naturally occurring metallic element. It is found in the ground and in rocks and, when located in water bearing aquifers, it will dissolve into the water. In recent years much attention has been brought to Chromium-6 (hexavalent chromium), which is one type of chromium. Chromium-6 contamination can be naturally occurring or caused by manufacturing processes.
Drinking water quality standards are set by the federal and state regulatory agencies. In Texas these agencies are the EPA and the TCEQ. When a contaminant is shown to cause adverse health effects, these regulatory agencies will set an Maximum Contaminant Level (MCL). MCLs are set at levels that are intended to protect the public health and be technologically and financially achievable for water systems. Currently the EPA and TCEQ have set an MCL of 100 parts per billion (ppb) for Total Chromium. The laboratory method for testing Total Chromium for Drinking Water Standards is required to have a minimum detection limit of 10 ppb. The Total Chromium results for Pecan Grove MUD’s drinking water quality testing have all shown levels of Chromium that are below the minimum detection limit.
The amount of Chromium-6 in the water is included with other types of chromium in the test result for Total Chromium. The EPA and TCEQ have not set an MCL for Chromium-6. However, the EPA is currently conducting a study to evaluate drinking water standards that may result in an MCL for Chromium-6. This EPA study is titled the “Unregulated Contaminant Monitoring Rule” (“UCMR”). This study is being performed by collecting and analyzing samples from drinking water systems around the country for a large variety of contaminants including Chromium-6. Unlike most public water systems in the area, Pecan Grove MUD participates in this study and has collected several samples testing for Chromium-6. The Chromium-6 test results from this study range from 0.236 ppb – 2.69 ppb. The California MCL for Chromium-6 is 10 ppb. While the current MCL for Total Chromium testing has a minimum detection limit of 10 ppb, the testing performed as part of the UCMR is much lower.
Drinking water, including bottled water, may reasonably be expected to contain at least trace amounts of some contaminants. Pecan Grove MUD’s water currently meets and exceeds all state and federal drinking water standards and in fact meets the stricter Chromium-6 standard set in California.