The Washington Aqueduct is responsible for drinking water treatment and regulatory testing for total chromium which includes chromium-3 and chromium-6. The Maximum Contaminant Level (MCL) for total chromium is 100 parts per billion (ppb).
In February 2011, DC Water and the Washington Aqueduct began voluntarily testing for chromium-6 on a quarterly schedule. DC Water collects samples from eight sites in the District's distribution system. The Washington Aqueduct collects samples from the source water and finished treated water. In 2014, as part of the Unregulated Contaminant Monitoring Rule 3, DC Water reported sample results for total chromium and chromium-6. These results can be found at in the emerging compounds section of our website and on the EPA's website.
| Chromium Monitoring Results (part per billion) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sampling Date | Feb 2011 | Apr 2011 | Aug 2011 | Nov 2011 | Feb 2012 | May 2012 | Aug 2012 | Nov 2012 | Feb 2013 | May 2013 | Aug 2013 | Nov 2013 | |
| Chromium-6 | Minimum | 0.07 | 0.00 | 0.04 | 0.03 | 0.08 | 0.02 | 0.03 | 0.04 | 0.05 | 0.04 | 0.05 | 0.06 |
| Maximum | 0.09 | 0.14 | 0.06 | 0.09 | 0.11 | 0.09 | 0.10 | 0.07 | 0.08 | 0.08 | 0.07 | 0.09 | |
| Average | 0.07 | 0.08 | 0.06 | 0.06 | 0.09 | 0.06 | 0.07 | 0.06 | 0.06 | 0.05 | 0.06 | 0.08 | |
