Mechanical Reliability in Potable Reuse: Evaluation of an Advanced Water Purification Facility

The mechanical reliability of a direct potable reuse (DPR) treatment train—consisting of ozone, biological activated carbon, microfiltration/ultrafiltration, reverse osmosis, and ultraviolet light with advanced oxidation—was evaluated using critical component analysis at the Demonstration Pure Water Facility in San Diego, Calif. Operators maintained logs of all mechanical issues that occurred over a yearlong test period; these were used to calculate several reliability metrics for the unit processes. Mechanical issues were also cross‐referenced with treatment performance data to determine whether any “critical” failures—i.e., those that impacted pathogen reduction performance—occurred. The results demonstrated that no critical failures occurred, though the communication systems experienced critical malfunctions. These malfunctions triggered an immediate system shutdown, mitigating the potential risk to public health. While several components experienced failures, malfunctions, and/or maintenance events, the processes maintained a high degree of availability, demonstrating that DPR facilities can be designed with a high degree of mechanical reliability.