Posting of Draft Report to the Legislature on the Feasibility of Developing Uniform Water Recycling Criteria for Direct Potable Reuse, Public Comment Period, and Workshops

On September 8, 2016, the California State Water Resources Control Board released its draft report to the Legislature on the feasibility of developing regulations for direct potable reuse (DPR) of recycled water. The public has 45 days to provide comments on the draft report through two public workshops or through written comment letters submitted to the State Water Board.

The draft report was developed after reviewing the recommendations of a 12-member expert panel of scientists and engineers and feedback from an advisory group made up of representatives from various stakeholder interest groups, including  water and wastewater  agencies, environmental nonprofits, public health officials, business community, taxpayer advocate organizations, government agencies, and other organizations in California.

In general, the expert panel found:

  • It is technically feasible to develop uniform water recycling criteria for DPR in California
  • The absence of an environmental buffer provided by indirect potable reuse (IPR) could be addressed for DPR through enhanced reliability of mechanical systems and treatment plant performance
  • There is no need for additional research to be conducted to establish criteria for DPR
  • Additional research in six areas should be conducted to enhance the understanding and acceptability of DPR and further ensure that public health is protected

The State Water Board agreed with the recommendation of the expert panel that the additional research work can occur concurrently with development of the uniform criteria for DPR; however, some critical knowledge gaps and the six research recommendations must be completed before uniform criteria for DPR can be adopted. No specific timeline for completing the research was provided although there was some mention of research work that will not be completed until the end of 2018 or possibly later. This indicates codified regulations may not materialize until 2020. The State Water Board will inform the public and stakeholders as key milestones are reached.

Here is a summary of the six research recommendations:

  1. Continue to improve on source control and final water quality monitoring, carry out an ongoing literature review to identify new compounds that may pose health risks particularly to fetuses and children from short term exposures.
  2. Implement a probabilistic method (Quantitative Microbial Risk Assessment, QMRA) to confirm the necessary removal values for viruses, Cryptosporidium and Giardia, based on a literature review and new pathogen data collected, and apply this method to evaluate the performance and reliability of DPR treatment trains.
  3. Require monitoring of pathogens in raw wastewater to develop better empirical data on concentrations and variability.
  4. Investigate the feasibility of collecting raw wastewater pathogen concentration data associated with community outbreaks of disease, and implement where possible.
  5. Identify suitable options for final treatment processes that can provide some “averaging” with respect to potential chemical peaks particularly for chemicals that have the potential to persist through advanced water treatment.
  6. Develop more comprehensive analytical methods to identify unknown contaminants, particularly low molecular weight compounds potentially in wastewater that may not be removed by advanced treatment and is not presently detectable by current regulatory monitoring approaches.

The State Water Board also noted that significant work is needed to address the recommendations provided by the expert panel and the advisory group regarding the non-treatment barriers that are part of ensuring the safety of DPR, including source control, wastewater treatment plant optimization, operator certification, and technical, managerial, and financial capacity.

Sarah Rhodes – RMC Civil/Environmental Engineer


WateReuse Meeting

WateReuse will hold a special Northern California Chapter Meeting on the Direct Potable Reuse Draft Report:

September 29, 2016 – 1 pm to 4 pm

Santa Clara Valley Water District Headquarters Boardroom

5700 Almaden Expy

San Jose, CA 95118

Public Workshops

Public workshops have been scheduled where public comments on the draft report will be accepted from the public.


October 4, 2016 – 9 am to 12 noon

Metropolitan Water District of

Southern California Headquarters

Room US1-102

700 North Alameda Street

Los Angeles, CA 90012


October 6, 2016 – 1 pm to 4 pm

Joe Serna Jr.-Cal EPA Headquarters Bldg.

Coastal Hearing Room

1001 I Street, Second Floor

Sacramento, CA 95814

*A live webcast of this meeting will be available on the internet. See:

For more information on the public workshops, please click the link below.

Draft Report

Please click below for a link to the draft report.