P3S Committee Past Chair Jonathon Powell with OCSan inspects an industrial site.

Road to DPR: What is Enhanced Source Control?

Wastewater News

Join the water reuse and enhanced source control track at the 2022 P3S Conference in Long Beach. Thursday’s session is moderated by Joshua Balentine, Brown & Caldwell, and features Kristel Baumgardner-Kranz, Carollo Engineers and Kevin Hardy, NWRI. Learn more >


What’s driving the need for enhanced source control research and regulations?

AB 574 requires the State Water Board to develop draft direct potable reuse (DPR) regulations by December 31, 2023.

An expert panel assembled in 2016 by the State Water Board reported that DPR is technically feasible. DPR is reusing water without a groundwater or environmental buffer, so purified water flows much more quickly from the WRRF to the Advanced Water Treatment Facility (AWTF) to the drinking water treatment plant.

The report outlined several areas where further research was needed in order for the State to develop DPR regulations. This included recommendations that more research and regulations be focused on industrial pretreatment inspections and standards, also known as source control. Local wastewater agencies regulate and monitor the flow of wastewater from industrial dischargers within the sewer shed.

The ultimate goal of enhanced source control is to prevent unwanted chemicals and compounds of emerging concern from entering the sewer system and impacting water quality further downstream. The drinking water community uses source control tactics around lakes and rivers that eventually become municipal drinking water supplies.

Who conducted the research?

The National Water Research Institute in Fountain Valley was assigned the enhanced source control research project by the State Water Board and in March 2020 submitted their research report. The advisory panel included Chair: Jeff Neemann, Black & Veatch; James Colston, Irvine Ranch Water District; Stuart Krasner, Independent Consultant; Ian Law, IBL Solutions and University of Queensland; and Amelia Whitson, EPA Region 9. NWRI staff included Kevin Hardy, Executive Director; Mary Collins, Communications Manager; and Suzanne Sharkey, Water Resources Scientist and Project Manager.

“Because the response time between treatment and distribution to consumers may be shorter in the case of DPR projects than for IPR projects, utilities that plan to add DPR to their water supply portfolio need to ensure that their industrial source control program is sufficiently rigorous to safeguard the quality of water it distributes to customers.” – NWRI Enhanced Source Control Expert Panel

Download the report >

CWEA photo

P3S Committee member Jason Finn, LACSD, demonstrates proper industrial facility inspection PPE.

What were their recommendations for enhanced source control?

A few of the report’s recommendations included:

  1. The National Pretreatment Program (NPP) is a solid foundation for enhanced source control.
    1. Use Waste Discharge Requirements (WDR) and NPDES permits to require pretreatment programs for all potable reuse systems.
    2. Establish source control as a component of an integrated water supply program.
    3. Provide adequate resources within Water Board/DDW to have a consistent programmatic approach to enhanced source control.
  2. Add explicit language to indicate that local limits must be designed to protect the wastewater collection system, the operation of the treatment plants, public health, and water
    quality for potable reuse. Use quantitative risk assessment for local limits to identify the constituents discharged, and in particular, concentrations of chemicals of concern (COC).
  3. Use risk assessment to screen business applications and permits for COCs.
  4. Establish sensor/monitoring systems in the collection system or at the WWTP to provide an early warning such as illegal or accidental discharges.
  5. Establish a public education and outreach program regarding control and disposal of hazardous constituents.
  6. Ensure that the Safe Drinking Water Act Requirements for technical, managerial and financial capacity apply to DPR projects.

What requirements are in the current draft of DPR regulations?

In 2021 the State Water Board released draft regulations for public comment and has since released updated drafts. Those regs included requirements for enhanced source control.

California’s Title 22 water recycling regulations already cover several requirements for source control.

The draft DPR regulations add additional elements:

  • Assess the risk of chemicals listed by the State Water Board for heightened monitoring
  • Conduct a fate assessment of COC
  • An outreach program that limits chemicals at the source
  • Up-to-date inventory of chemicals identified, including new sources
  • The DPR agency will work with the WRRF agency to use local limits to protect water quality and public health
  • Source control must be audited every 5 years
  • Joint plan with monitoring technologies needs to be in place
  • A source control committee with each of the agencies represented needs to be formed

What are examples of enhanced source control from other locations?

The NWRI report includes several case studies about enhanced source control that is part of the Singapore Public Utilities Board’s NEWater Project.

Critical elements to NEWater’s success

• Discharge regulations.
• Regular monitoring and industry inspections.
• Use of analyzers to monitor volatile organic chemicals (VOCs). There are 40 analyzers in the wastewater collection system and 25 at industrial premises.
• Use of 375 pH analyzers installed at industrial premises and connected to lockable valves that are activated if pH is outside the regulated range.
• Use of 42 microbial fuel cells for 24/7 measurement of heavy metals, cyanide, pH, and ORP. Deployment of 100 units at permitted industry sites , with plans to install 100 units in the
wastewater collection system.
• Use of robotics to enter and sample from wastewater collection system when illegal discharges are detected.
• Drone surveillance.
• Ongoing research and development on the use of fluorescence analyzers at nodal points to monitor organics.

What happens next?

The State Water Board Division of Drinking Water staff continues to refine the draft DPR regulations with public input. There are several expert panels working on different aspects of research and will soon provide their final reports. The Water Research Foundation is also wrapping up research projects that will inform DDW’s development of regulations.

The State Water Board should be considering DPR regulations sometime towards the end of 2023.

Further Resources

CWEA Resources