The world's first government-mandated microplastics testing program, and what it required.
In 2018, California passed SB 1422, the California Safe Drinking Water Act's microplastics provision — the first law anywhere in the world to mandate microplastics testing in drinking water [1]. It directed the State Water Resources Control Board to adopt an official definition of microplastics by July 2020, establish a standard testing methodology, require four years of testing and public reporting, and accredit labs to perform the testing by July 2021.
The Board approved its implementation policy handbook in September 2022, and Phase One testing — focused on large, untreated community water systems — began in fall 2023, running through 2025 [1].
SB 1422 is the practical proof that government-grade, standardized microplastics testing is achievable at scale, not just a research-lab exercise — and its lab-accreditation requirement (tying the testing mandate to accredited analytical capacity, not just a testing method on paper) is the same structural choice the MPFREE Standard makes in requiring ISO/IEC 17025-accredited partner labs rather than accepting self-reported results.