South Orange County agencies weigh stricter pretreatment standards to enable potable reuse

South Orange County agencies weigh stricter pretreatment standards to enable potable reuseAs Southern California water districts explore potable reuse from the Latham treatment plant, regional officials are pushing to tighten industrial discharge standards to meet stringent advanced treatment requirements.

Regional agencies are considering upgrading industrial pretreatment standards to facilitate future indirect or direct potable reuse from the Latham plant.

The push for stricter discharge limits follows concerns from industrial users in the Santa Margarita Water District regarding future discharge requirements and costs.

The Irvine Ranch Water District expects to begin construction this year to expand its Siphon Reservoir from 500 to 5,000 acre-feet for recycled water storage.

Separately, the South Coast Water District faced a class-action lawsuit threat from a ratepayer over recently approved capacity and service fees.

Water agencies in South Orange County, California, are laying the groundwork for future potable reuse projects, a move that is expected to force a tightening of regional industrial pretreatment standards. During a July 23 meeting of the South Coast Water District board, directors discussed regional efforts to utilize effluent from the Latham plant for either indirect or direct potable reuse. To enable this, officials noted that industrial pretreatment requirements will need to be significantly more stringent than the current standards enforced by the regional wastewater authority. The transition is already prompting discussions with industrial dischargers within the Santa Margarita Water District service area, who have raised concerns about what the future discharge limits might be. Regional leaders plan to formally suggest that the regional board begin developing stricter pretreatment standards and estimating associated costs to better position the agencies for the eventual reuse transition. Alongside the reuse planning, neighboring agencies are advancing major recycled water storage projects. The Irvine Ranch Water District is finalizing wildlife agency permits to expand its Siphon Reservoir from 500 acre-feet to 5,000 acre-feet to store recycled water. Construction on the expansion is expected to begin before the end of the year. In other regional supply developments, the City of Laguna Beach is beginning construction on a new well that will allow it to draw two-thirds of its water supply from the Orange County Water District Basin. Locally, the South Coast Water District formally approved adding its annual water capacity, capacity demand, and sewer block fees to the 2026/2027 county tax roll. The unanimous board approval came despite a public comment from a resident, identified as Mr. Hoffman, who threatened a class-action lawsuit against the district over the recently approved rates, warning of "significant financial implications" for the utility.