Dallas Water Utilities experienced an outage at the Elm Fork Drinking Water Treatment Plant on December 10. As a result, the facility failed to meet the minimum treatment technique requirements that day when its water system failed to properly disinfect the drinking water for a period of more than four hours. DWU has indicated that the water was safe to drink. No adverse chemical compounds or pathogens were found in the water.
The failure was caused by a problem with the ozone system. The plant still produced and delivered water with a chlorine-based disinfectant.
As recommended by the US EPA, Dallas uses a multi-barrier system that protects the water should any one element of the system fail. Thus by combining filtration, ozone and chlorine, even with a failure of one element, the water produced was still safe to drink.