Microplastics are ubiquitous in the environment and are emerging as a potential concern in drinking water. While scientific research around microplastics is evolving rapidly, many uncertainties remain. The SWRCB DDW is working to meet legislative requirements of SB 1422 (Microplastics in Drinking Water, 2018) that requests adoption of testing and reporting of microplastics in drinking water. To support this effort, workshops were held in Southern and Northern California on February 11 and 13, 2025, respectively, offering information on the collection of drinking water samples for microplastic analysis.

This page contains workshop materials, including the agenda, presenters’ bio, presentation slides, and training resources on sample collection. The workshops included:

• DDW’s update to SB 1422: An update was provided on DDW’s ongoing efforts in response to SB 1422, recognizing the rapidly evolving nature of this issue.
• Sample collection method: Training was delivered through lecture, training video, and hands-on demonstration on a proposed method to collect drinking water samples for microplastic analysis.
• Microplastic analysis overview: An overview was provided on the necessary steps of the analytical methods – following sample collection – and associated QA/QC procedures.
• Health effects update: The current scientific understanding of potential health risks associated with microplastics was discussed.

Key Takeaways from the Workshop

• Because microplastics are ubiquitous in the environment, controlling contamination is critical to ensure the quality of the data obtained.
• Highly trained and specialized analysts are required considering the complexity of the analytical methods and equipment used.
• Several parameters are required to characterize microplastics, including concentration, polymer type, size, shape, color, etc.
• Although microplastics have been detected in various parts of the human body, health effects remain unclear.
• Recognizing that microplastic science is evolving rapidly, these workshops presented the state of science at the time. Additional work is needed to clarify the uncertainties remaining.

Screenshot from the training video: