Plastic pollution is now a defining issue of modern life, with microplastics - tiny plastic particles less than 5 millimetres in size - found everywhere from the deepest oceans to drinking water.

Microplastics infiltrate ecosystems, harm marine life, and pose unknown risks to human health. Until now, however, there has been no universally accepted approach to sampling microplastics in water, which has hampered efforts to understand the extent of the problem and regulate it effectively.

BS ISO 5667-27:2025 Water quality - Sampling - Part 27: Guidance on sampling for microplastics in water is a new standard that provides a standardized methodology for sampling microplastics in various water sources, including domestic water, freshwater, seawater, treated and untreated wastewater.

By adopting a uniform set of protocols, this standard helps researchers and regulators obtain more accurate, comparable data on microplastic contamination, supporting critical research and informing regulatory actions.

BS ISO 5667-27 sampling methods for suspended microplastics

BS ISO 5667-27:2025 focuses on sampling methods for suspended microplastics in water. It outlines basic approaches, including:

• Grab sampling, a method of collecting a water sample at a specific point in time.

• Cascade filtration, which involves passing water through a series of filters with different pore sizes to separate microplastics based on size.

• Net sampling, which employs nets such as manta, plankton, or neuston nets to collect microplastics from the water.

These methodologies address the complexity of microplastics, which vary in size, shape, buoyancy, and level of colonization by microorganisms. Importantly, the standard does not cover chemical, biological, or physical analysis methods, focusing purely on the sampling aspect.

Learn more about how standards are supporting water quality by visiting our Water topic page.

Who should use BS ISO 5667-27?

BS ISO 5667-27:2025 is designed for a wide range of users who are involved in water quality monitoring and environmental protection, including:

• Water treatment and purification companies: To assess and improve their processes for removing microplastics from water.

• Government agencies and regulatory bodies: To support the development and enforcement of regulations concerning microplastic pollution.

•  Academic and research institutions: To standardize research methods in studies on microplastics and environmental health.

• Environmental consulting firms: To provide expert guidance and consulting services on microplastic sampling and mitigation strategies.

5 benefits of using BS ISO 5667-27?

This new standard offers several key benefits to its users:

1. Improved data consistency: By standardizing sampling methods, BS ISO 5667-27 reduces variability in data collection, allowing for more accurate comparisons across different studies and regions.

2. Targeted research support: Researchers can now apply a more specific and standardized approach to microplastic sampling, which will enhance understanding of how these particles move through and affect the environment.

3. Enhanced regulation: Government agencies and regulatory bodies can use the standard to develop clearer, evidence-based regulations on microplastic pollution, helping to curb its release into the environment.

4. Support for water treatment improvements: Water treatment companies can assess the efficiency of their processes in removing microplastics, potentially leading to technological innovations in purification systems.

5. Global applicability: As part of the BS ISO 5667 series, this standard can be applied internationally, facilitating collaborative efforts to address a global environmental challenge.

To learn more about what this standard covers and its benefits, download our free Executive Briefing here.

Understanding the BS ISO 5667 series

BS ISO 5667-27:2025 is part of the broader BS ISO 5667 series, which provides comprehensive guidance on sampling for water quality.

Key related standards include:

• BS ISO 5667-1: General guidance on water sampling.

• BS ISO 5667-3: Guidance on the preservation and handling of water samples.

• BS ISO 5667-17: Guidance on the sampling of bulk suspended solids.

These standards together form a robust framework for assessing various water quality parameters, with BS ISO 5667-27:2025 addressing the specific challenges posed by microplastics.

In an era where plastic pollution poses significant threats to ecosystems and human health, BS ISO 5667-27:2025 offers an essential tool for researchers, regulators, and industry professionals alike. Get your copy here today.

Thirst for Change: Accelerating progress to a water secure world

At BSI, we believe individuals and organizations can come together to accelerate progress towards a sustainable world, one in which there is a reliable supply of essential freshwater.

Read more here or watch the video.