Microplastics represent a class of emerging contaminants that are defined as plastic particles less than 5 mm in size. These particles, which also include nanoparticle-sized plastics, are ubiquitous in the environment and have been reported to be found in drinking water. Although microplastics legislation has largely focused on drinking water and aquatic systems, recycled water facilities are integrally connected to those systems via potable and non-potable reuse applications and could be affected in the future.


Microplastics come from a variety of primary (e.g., microbeads in personal care products that are washed into wastewater systems from households) and secondary (e.g., breakdown of larger plastics through weathering) sources. Research has shown that microplastics are present in engineered water systems, including drinking water, wastewater, stormwater, and recycled water.


Plastics and microplastics have been the subject of regulatory or legislative actions at both the federal and state level including bans (plastic bags, single use plastics, and straws), restrictions (plastic pellets and personal care products), and regulations (requiring monitoring at permitted facilities, primarily drinking water). Although California leads the way in terms of microplastics-related legislation, there is momentum in other areas of the country as task forces, studies, monitoring, bans, and restrictions on plastics advance stakeholder engagement in the topic.

Key considerations for reuse

Facilities connected to drinking water and aquatic systems via potable and non-potable reuse applications may be the next group affected by microplastics regulations. Public and private sector entities engaged in reuse should consider several proactive measures.

  • Monitoring and sampling planning: Regulatory updates may include changes in monitoring and sampling requirements for source and treated water, which require nuanced, time-consuming, and often expensive sampling and analytical methods. Additional costs and staff resources should be factored into future operations plans and budgets.
  • Treatment upgrades: While wastewater resource recovery facilities capture a significant amount of microplastics through treatment, these facilities were not specifically designed for this purpose. As a result, system upgrades may be triggered for compliance by future regulations, particularly for biosolids where many of the microplastics are concentrated. Treatment options and upgrade projects can be explored in advance and considered in future planning and budgets.
  • Local limits: As regulations evolve, utilities may set new local limits for industries discharging to the collection and treatment system. Staying informed on emerging regulations, building relationships with local utility partners, and planning for potential sampling, monitoring, and treatment can help address future regulatory requirements.
  • Public and stakeholder outreach: Unlike other emerging contaminants (e.g., PFAS, pesticides, etc.), microplastics are “tangible” to the average consumer, which has led to extensive coverage in the media and subsequent inquiries to water utilities. As this topic takes a more prominent position in the news and in emerging regulations, consumers and stakeholders will be asking questions. Take the time to stay informed and conduct proactive communications and educational outreach as appropriate for your operations.

In this evolving regulatory environment, these considerations may also be useful for water facilities and industry outside of the scope of reuse as well.

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