DDW Proposes Microplastics Definition

This morning the State Water Resources Control Board (SWRCB) Division of Drinking Water (DDW) posted for public comment a proposed definition of microplastics in drinking water (Microplastics_DDW Proposed Definition).  Also enclosed is the DDW staff report describing the research and process to develop the definition. (DDW Staff Report_Microplastics)

DDW’s Proposed Definition of Microplastics

‘Microplastics in Drinking Water’ are defined as solid polymeric materials to which chemical additives or other substances may have been added, which are particles which have at least two dimensions that are greater than 1 and less than 5,000 micrometers (μm). Polymers that are derived in nature that have not been chemically modified (other than by hydrolysis) are excluded.

[Note: DDW’s proposed definition includes two footnotes that expand on the text.  See the enclosed document.]

Next Steps

  1. The SWRCB will hold a workshop on the definition of ‘Microplastics in Drinking Water’ on April 8, 2020 at 9:30 a.m., available via webcast (https://video.calepa.ca.gov/).
  2. Written comments are due by 12:00 noon on Friday, April 24, 2020.
  3. A resolution to adopt the proposed definition will be on the agenda for the SWRCB Meeting on Tuesday, June 16, 2020 at 9:30 a.m.  Also available via webcast (https://video.calepa.ca.gov/).


Senate Bill 1422 was signed into law in 2018 (adding section 116376 to California’s Health and Safety Code).  This new law requires the following activities from DDW:

  1. On or before July 1, 2020: adopt a definition of microplastics in drinking water;
  2. On or before July 1, 2021:
    1. Adopt a standard methodology for testing of microplastics in drinking water;
    2. Adopt requirements for four years of testing and reporting of microplastics in drinking water, including public disclosure of those results;
    3. Consider issuing quantitative guidelines (e.g., notification level) to aid consumer interpretations of the testing results, if appropriate; and
    4. Accredit qualified laboratories in California to analyze for microplastics in drinking water.
This entry was posted in Water News on by .

About Dan Askenaizer

Dr. Askenaizer leads WQTS’ work on regulatory compliance support for many of our water agencies clients. Dr. Askenaizer tracks water quality and treatment regulations at the Federal and State levels and provides regulatory updates to our clients. Dr. Askenaizer has strong expertise in the development of Regulatory Monitoring and Compliance Plans (RMCPs), which he has completed for a number of water agencies. He has also been working on a number of projects dealing with the development of distribution system monitoring plans and review of nitrification control strategies. Prior to joining WQTS, Dr. Askenaizer was the Water Quality Manager for the Glendale Water and Power. Under his leadership, the Water Quality Group conducted a demonstration-scale study of chlorite for nitrification control and a pilot-scale study of biological treatment for removal of nitrate. Dan has 30 years of experience working on projects dealing with regulatory, water quality and public health issues. Dan has given numerous presentations at workshops and round-tables across the country for water utilities. Dan was instrumental in developing and implementing a Mentoring Program for water staff and was involved in a Sustainable Development team.