OMWD Customers Not Impacted By Twin Oaks Water Treatment Violation

OMWD’s water quality has not been impacted by recent events at the San Diego County Water Authority’s Twin Oaks Valley Water Treatment Plant. Water served to OMWD customers continues to meet or exceed all state and federal water quality standards for drinking water.

The San Diego County Water Authority reported to its member agencies on June 4 that it received a Notice of Violation for a water treatment process issue that took place at the Twin Oaks Valley Water Treatment Plant on April 21, 2019. In consultation with the State Water Resources Control Board’s Division of Drinking Water staff, SDCWA determined that water quality was not compromised and there was no public health concern due to multiple processes that are in place to ensure continuous protection. However, due to the nature of the issue, SDCWA is required to provide public notice of the violation.

Though many San Diego County agencies routinely serve to their customers water treated at Twin Oaks, OMWD does not. Over 98 percent of water delivered to OMWD customers is treated at OMWD’s David C. McCollom Water Treatment Plant. OMWD was not serving water treated at Twin Oaks at the time of the treatment process issue.

There are a variety of safeguards in place at the David C. McCollom Water Treatment Plant to ensure the exceptional water quality enjoyed by OMWD customers. The plant will automatically discontinue production if treated water does not meet specific water quality thresholds, and in a variety of other circumstances. Additionally, plant operators regularly monitor in real-time water quality measures in both the source water entering the plant and the treated water leaving the plant.

OMWD customers with questions about water quality are invited to review the annual Consumer Confidence Report on water quality, which is available at More information about recent events at Twin Oaks Valley Water Treatment Plant is available at or by calling SDCWA at 858-284-4142.