SB 504 Michigan Senate · 2025-2026 Regular Session

Water supply: quality and standards; testing and reporting of the amount of microplastics in public drinking water supplies; require. Amends sec. 5 of 1976 PA 399 (MCL 325.1005) & adds sec. 6a.

SB 504 requires Michigan to test public water supplies for tiny plastic particles (microplastics) starting in 2027, with quarterly sampling through 2030. It focuses testing on water sources near Great Lakes shorelines, agricultural areas, landfills, and groundwater systems, using methods aligned with federal or state standards. By July 2031, the state must report findings - including microplastic levels, sources, and potential health impacts - and recommend next steps for monitoring or regulation. This directly affects all public water systems in Michigan, including those serving communities near environmental justice concerns.

Issues: ✓ Environment

Bill status in committee 1 of 4 stages cleared

Introduction

Aug 2025

Committee Review

Floor Vote

Governor

Introduced Aug 14, 2025 Last action Mar 11, 2026

Maddy AI version diff · 1 comparison

What changed between versions

Senate Introduced Bill → Substitute (S-1) · 4 edits

MODERATE

The bill was amended to clarify that the microplastics program is an exploratory sampling initiative rather than a universal regulatory mandate, removing a requirement for quarterly testing in favor of a more flexible approach. The definition of microplastics was expanded to include particles up to 5,000 micrometers, and the reporting timeline was adjusted to allow for coordination with health officials before submitting final results.

Scope change

The scope of the microplastics program was narrowed from a mandatory, universal monitoring requirement to a targeted sampling and assessment program intended to study prevalence and risks without immediate regulation.

REQUIREMENT

Changed the microplastics program from a mandatory quarterly testing schedule to a flexible sampling program that coordinates with universities and other agencies to develop methods.

Added a requirement for the department to coordinate with the Department of Health and Human Services to provide public guidance on microplastic risks and exposure reduction.

DEFINITION

Updated the definition of 'microplastics' to include particles up to 5,000 micrometers in all dimensions, expanding the range of materials considered.

TIMELINE

Modified the reporting timeline to allow for a preliminary assessment and coordination phase before the final report is due in 2031.

Floor votes

How they voted

No floor votes recorded yet.

Full legislative history

Actions timeline

Total actions

Key actions

Committee

Mar 11, 2026

Committee

REFERRED TO COMMITTEE OF THE WHOLE WITH SUBSTITUTE (S-1)

upper

Mar 11, 2026

Upper · Passed

REPORTED FAVORABLY WITH SUBSTITUTE (S-1) 3/10/2026

upper

Aug 14, 2025

Committee

REFERRED TO COMMITTEE ON NATURAL RESOURCES AND AGRICULTURE

upper

Aug 14, 2025

Introduced

INTRODUCED BY SENATOR DAYNA POLEHANKI

upper

1 primary · 7 co-sponsors