This project focuses on the design of a tertiary water treatment facility employing Direct Potable Reuse (DPR) to provide a sustainable drinking water solution for residents in and around Laguna Niguel, California. The proposed facility treats secondary effluent from an existing wastewater treatment plant, utilizing a multi-step treatment train to ensure compliance with stringent drinking water quality standards. Key processes include ozone disinfection, membrane filtration, reverse osmosis, and ultraviolet light treatment, alongside advanced oxidation and biological activated carbon filtration. Environmental and regulatory considerations were integral to the design, aiming to address water scarcity and mitigate the effects of drought while minimizing ecological impacts. The resulting potable water is pumped directly into the local drinking water distribution network, reinforcing long-term water resilience for the community.