A direct potable reuse (DPR) pilot in Polk County, Florida, demonstrated how utilities can navigate evolving regulations while developing treatment data for a future full-scale project, according to Angel Villarruel-Moore, staff professional with Carollo Engineers, during a WEFTEC 2026 session.

The One Water Polk pilot was developed as Florida was establishing its first direct potable reuse regulations. Florida’s Department of Environmental Protection began its DPR rulemaking process in 2020, while the pilot’s source water characterization was completed the same year. Pilot operations began in August 2023 and concluded in January 2025. The final potable reuse rules were adopted the following month.
Polk County Utilities selected its Northwest Regional Service Area for the pilot because it primarily receives domestic wastewater and had an existing reclaimed water system near a new water production facility. The site also had excess reclaimed water availability throughout the year. The project was driven in part by population growth and projected water supply limitations in Central Florida.
The permanent pilot produced 8 gallons per minute of finished water and used a carbon-based advanced treatment process. Treatment included ultrafiltration for pathogen removal and UV disinfection for pathogen inactivation. The pilot also incorporated bypasses that allowed researchers to evaluate treatment configurations and their effects on downstream processes.

Those bypasses proved valuable during the project. Testing showed that keeping the initial Floxet pretreatment process online reduced organic loading and extended granular activated carbon (GAC) media life, providing potential cost savings for full-scale design. The pilot also evaluated whether ultrafiltration could be bypassed while still meeting pathogen removal requirements, although changes to the final rules ultimately reinforced the value of retaining UF.
Regulatory changes required the project team to adjust its testing program during operations. Early draft rules allowed pathogen removal targets to be established through several approaches, including a site-specific gap analysis and quantitative microbial risk assessment. Under the final rules, the project relied on a uniform log removal value approach with more conservative requirements than initially anticipated.

The pilot also initially anticipated 12 months of operation across several treatment configurations. After discussions with regulators, the team determined that 12 months of operation using the anticipated full-scale treatment configuration would be more appropriate. The pilot was ultimately extended by three months rather than the six months initially contemplated, using additional water quality data collected during the project.

Another significant change involved validation of the ozone and biologically activated carbon system. Instead of conducting a more cumbersome contaminant-spiking challenge test envisioned under the original provisions, the final rules used a performance-based indicator framework that allowed the project to rely on existing water quality data.

Villarruel-Moore said the experience demonstrated the importance of treating a pilot testing plan as an adaptable document rather than a fixed program. Frequent coordination with regulators helped the project adjust sampling and reporting requirements while maintaining its goal of producing a permit-ready dataset.

Regulatory engagement also influenced Florida's final rules. The One Water Polk team raised concerns that early draft provisions were focused heavily on reverse osmosis-based treatment and worked with regulators to address how carbon-based advanced treatment should be incorporated. The final rules included defined requirements for both reverse osmosis-based and carbon-based advanced treatment, according to Villarruel-Moore.

The project also emphasized involving utility operators early. Polk County included both water and wastewater operators in the pilot, allowing staff to become familiar with the equipment and participate in daily rounds. Although the final operating arrangement placed responsibility with water plant operators, the broader participation provided operational experience during the pilot.

Villarruel-Moore said utilities considering DPR pilots should anticipate regulatory changes, build operational flexibility into their projects and coordinate with regulators early and often. Maintaining current pilot reports and documenting changes can also help utilities build the data needed for future permitting.

The pilot also generated data on PFAS. Villarruel-Moore said regulated PFAS compounds were below their respective maximum contaminant levels in the pilot. Source water contained approximately 10 to 12 parts per trillion of PFAS, and the Floxet pretreatment removed about 50% of total organic carbon before the GAC system, helping extend GAC bed life. The project also tested PFAS precursors and multiple analytical methods.

For utilities in states where DPR regulations are still developing, Villarruel-Moore said the absence of finalized rules should not necessarily prevent pilot work. Instead, utilities can draw on industry knowledge to anticipate potential regulatory requirements while designing projects that can adapt as regulations evolve.