What is Compostability Testing and Why Does it Matter

In an time of increasing environmental awareness, the terms “compostability” and “biodegradability” are more important than ever. But simply claiming a product is compostable is not enough. Compostability testing exists to validate those claims and verify that a material or product will actually break down in compost environments under certain conditions. In this post, we will explore what compostability testing is, how it works, what standards apply, and why it matters for brands, consumers, and the planet.

What Is Compostability?

Before diving into testing, it helps to clarify what compostability means. Compostability refers to the ability of a material to break down into natural elements, such as carbon dioxide, water, mineral salts, and biomass, within a composting setting, leaving no toxic residue. Compostable items should also disintegrate physically (so they do not leave large fragments), not negatively impact the composting process, and produce compost of good quality in terms of plant and seed health and safety.

Why Compostability Testing Is Critical

• Credible environmental claims: Consumers are increasingly skeptical of vague “green” labels. Compostability testing supplies scientific proof that a product does what it claims.
• Regulatory compliance: Many regions require proof that packaging or materials labelled compostable meet specific standards before they may be marketed as such.
• Avoid incorrect claims: Without testing, materials claimed to be compostable may not perform under real composting conditions, leading to backlash, legal challenges, or waste rather than benefits.
• Quality of compost: Compostability testing ensures that the material, once composted, will not harm soil, plants, or the broader ecosystem.

Key Standards for Compostability Testing

Several internationally recognized standards define how compostability must be tested. These include:

These standards not only focus on how fast or completely a material breaks down, but also on chemical composition, ecotoxicity, and physical disintegration.

Industrial/Municipal Vs. Home Compostability

Many of the most common compostability testing standards (e.g. EN 13432, ASTM D6400, and ASTM D6868) are designed to assess materials and products that are expected to be collected for disposal at industrial or municipal composting facilities. Such facilities are managed to efficiently and effectively convert biowaste into healthy compost by carefully controlling conditions such as temperature, moisture, and oxygen exposure. These same conditions are not common for most at-home composting situations, so it should not be assumed that a material or product, which has met the requirements for an industrial compostability classification, will necessarily perform well under home composting conditions.

It is also important to consider that, even though a material or product may meet the testing requirements for industrial compostability, composting facilities may not accept the material as a feedstock. Composting facilities must be able to quickly and easily distinguish between compostable and non-compostable materials, so materials that are not commonly compostable may not be accepted. Materials that are commonly accepted at composting facilities include those that are associated with yard waste (lawn and leaf bags and potting materials) and food waste (cutlery, cups, and plates).

To ensure that materials and products will sufficiently degrade under home composting conditions, they should be tested using a standard specifically designed to assess for home compostability. Test standards for home compostability are not as prevalent as for industrial/municipal compostability, but the Australian method, AS 5810, is one such standard. Home compostability testing is performed at lower temperatures, and degradation typically occurs over a longer period of time compared to industrial compostability testing.

Phases of Compostability Testing

Compostability testing generally consists of several interrelated stages:

1. Chemical Characterization & Identification
   The product’s ingredients, additives, coatings, and other components are examined. Tests check for heavy metals, toxic chemicals, other potentially harmful substances, and volatile solids.
2. Biodegradation Test
   Measures how much of the material breaks down biologically, usually to carbon dioxide under aerobic conditions. For example, a product must biodegrade by about 90% when normalized against the positive control within 6 months.
3. Disintegration (Physical Breakdown)
   After composting for a set time (often 12 weeks under ISO 20200), the sample must break down into small fragments (e.g., pass through a 2 mm mesh sieve). Only a small fraction (often ≤10%) of the mass should fail to pass through the sieve.
4. Ecotoxicity / Quality of Final Compost
   Even if a product disintegrates and biodegrades well, the resulting compost must be safe. That means it should not inhibit plant growth or seed germination, and it must have low levels of heavy metals and other harmful substances.
5. Other Factors
   • Temperature, moisture, and oxygen levels will mimic the typical industrial composting environment.
   • Duration: Some tests take 45 days, others up to 180 days or more, depending on the standard.

Why Compostability Testing Matters for Businesses

• Brand credibility & trust: Products that are independently tested and certified carry more weight with consumers.
• Regulatory risk mitigation: As laws around single‐use plastics and waste tighten, compliance with compostability standards becomes a competitive advantage or even a necessity.
• Environmental impact: Properly compostable products reduce waste, decrease greenhouse gas emissions, enrich soil, and contribute to circular economy principles.
• Market differentiation: Compostability can be a distinguishing feature in packaging, food service, textiles, and many other industries.

How to Get Started with Compostability Testing

If you are considering having your product undergo compostability testing, here are practical steps:

1. Define your target composting environment: Industrial/municipal, or home composting?
2. Identify applicable standards: EN 13432, ASTM D6400, ASTM D6868, etc.
3. Select a certified lab or testing provider: Look for labs that are ISO/IEC 17025: 2017 accredited for those standards.
4. Run initial screening: You might want to consider conducting a screening test first to weed out poor-performing materials.
5. Proceed with full testing: Once you have positive results from a screen test, conduct the full certified test on the material.

Conclusion

Compostability testing is a critical tool for ensuring that your product’s environmental promise truly holds up. By understanding the processes, standards, and potential pitfalls, businesses can develop products that not only claim to be compostable but also deliver on this promise. For consumers and the planet, that means less waste, healthier soil, and stronger trust in the sustainability commitments we make.

If you are interested in compostability testing, partnering with an ISO/IEC 17025:2017 accredited and experienced laboratory can streamline the process, reduce uncertainty, and provide expert guidance at every stage. At RespirTek, we specialize in compostability testing, helping businesses confidently meet their compostability testing goals while ensuring compliance with industry regulations. Our team provides comprehensive data progression updates throughout the entire testing process, keeping you informed every step of the way. Contact us today to take the next step toward obtaining compostability certification and making a meaningful impact on environmental sustainability.