When did the City learn about the May 2019 benzene contamination and how quickly did the City switch to a different water supply?

On May 9, 2019, the City received results from a single annual water quality test sampled on April 30, 2019 that showed higher-than-usual levels of benzene. In compliance with state water quality procedures, a second confirmation test was arranged to confirm the finding. After the additional testing from an independent laboratory analysis and confirmation of the results, the City transitioned its water supply to the approved back-up supply through Metropolitan Water District (MWD) on May 15, 2019.