Search "biodegradable trash bags" and you will find products claiming to break down naturally, decompose safely, or vanish over time. None of these claims mean anything without a certification behind them. That is the core problem with the term biodegradable, and it is exactly why California passed a law to address it. If you are trying to figure out whether a bag labeled biodegradable is actually going to compost, the honest answer is: you cannot know without checking for a specific certification. Here is why that distinction matters more than most shoppers realize.
What "Biodegradable" Actually Means (and Why It's So Vague)
Biodegradable simply means a material will eventually break down through biological activity. That's it. There is no required timeframe, no required testing standard, and no independent verification built into the word itself. A plastic bag can technically be labeled biodegradable if it breaks down over 50 years, leaves behind microplastic fragments, or requires conditions that never occur outside a lab.
Manufacturers can print "biodegradable" on packaging without submitting to any third-party lab test. No agency checks the claim before it goes on a shelf. That is not an accusation against every brand using the term, it is simply a fact about how loosely the word is regulated.
What "Compostable" Means, and Why Certification Matters
Compostable is a different category entirely. To legally use "certified compostable" language, a product must pass third-party laboratory testing against a specific standard, either ASTM D6400 in the US or EN 13432 in the EU. These standards require the material to disintegrate into carbon dioxide, water, and organic matter, with no toxic residue and no microplastics left behind.
BPI certification is one of the most recognized marks tied to ASTM D6400 compliance. It is not a self-declared claim. Brands submit products for independent lab testing and must demonstrate compliance before certification is granted. The same rigor applies to TUV Austria certification, which covers both OK Compost INDUSTRIAL (commercial composting facilities) and OK Compost HOME (backyard compost bins).
Industrial composting standards require 90% disintegration within 84 days under ASTM D6400, or 90 days under EN 13432, at high temperatures around 55-60 degrees Celsius with controlled humidity and microbial activity. Home composting under OK Compost HOME requires 90% disintegration within 180 days at ambient backyard temperatures. These are measurable, tested outcomes. Biodegradable has none of that.
Biodegradable Trash Bags vs Compostable Trash Bags: The Real Difference
Here is where the distinction gets practical. A biodegradable trash bag might be made from conventional plastic with an additive that helps it fragment faster. It may never fully break down into organic matter, and no lab has confirmed it will. A certified compostable trash bag has been tested to confirm it breaks down completely under specific conditions, with the certification number to prove it.
This is not a minor labeling technicality. If your city curbside compost program or backyard bin ends up full of "biodegradable" bags that never actually decompose, that contamination affects the whole batch of finished compost, and eventually the soil it goes into. This is exactly the industry problem regulators are trying to solve, and it's one reason I take a firm stance here: if a bag doesn't carry BPI certification, ASTM D6400 compliance, or a TUV Austria mark, don't assume it belongs in a compost bin.
At GreeneWrap, every trash bag size, from the 1-2 gallon kitchen bags up through the 90-95 gallon heavy-duty yard waste bags, carries BPI certification, TUV Austria certification, and meets both ASTM D6400 and EN 13432 standards. We never describe our own products as biodegradable. That word doesn't carry the proof our customers are looking for, and we'd rather use language backed by testing.
Why California's AB 1201 Targets This Exact Confusion
California's AB 1201 addresses this problem directly. The law requires that any product labeled compostable be third-party certified, and it prohibits products containing PFAS from carrying a compostable label at all. It also bans deceptive look-alike products, meaning packaging that visually mimics certified compostable items without actually meeting the standard.
The law exists because non-certified products that look identical to certified ones have been contaminating composting systems and, in some cases, farmland soil. Many compostable fiber products have historically contained PFAS, which persist through the composting process instead of breaking down. BPI has already stopped certifying compostable fiber products with intentionally added fluorine, and AB 1201 pushes that standard further at the state level. CalRecycle has been directed to develop formal labeling requirements to enforce this going forward.
On PFAS specifically: some compostable products on the market may contain PFAS, so it's worth checking certification before assuming any bag is free of it. GreeneWrap products are confirmed PFAS free and fluorine free by the manufacturer. That's a claim specific to our products, not a blanket statement about the industry.
How to Read a Label Before You Buy
If you're standing in front of two boxes of trash bags trying to figure out which one actually does what it claims, look for these specific marks rather than the word "eco-friendly" or "biodegradable" on the front of the package:
- BPI Certified logo, tied to ASTM D6400 compliance
- TUV Austria OK Compost INDUSTRIAL, for commercial composting facilities
- TUV Austria OK Compost HOME, for backyard compost bins
- EN 13432 compliance, relevant if you're comparing products sold in the EU
If none of these appear anywhere on the packaging, the product is likely relying on the vague biodegradable claim rather than a tested compostable standard. That distinction should change how you use it and where you dispose of it.
Choosing the Right Certified Compostable Bag for Your Home
Once you're looking at certified options, sizing matters more than most people expect. A lot of the confusion in this space isn't really about biodegradable versus compostable, it's about picking the wrong size and assuming the bag failed when it was just overloaded or under-ventilated.
For kitchen food scraps, a 1-2 gallon or 2-4 gallon bag keeps daily waste manageable and easy to transfer to a larger bin. For a standard kitchen trash can, the 13 gallon compostable trash bags with drawstring closure are one of our most searched sizes, and for good reason, they fit the most common household trash can dimensions. If you're managing bathroom or smaller bins, the 4-6 gallon or 6-8 gallon sizes work well. For yard waste or job-site cleanup, the heavy-duty 2 mil bags starting at 50-55 gallon up through 90-95 gallon are built for that kind of load, not for a kitchen counter.
If you're storing food separately from trash, compostable food storage bags in gallon, quart, sandwich, or snack sizes are a separate certified product line, built with resealable closures rather than drawstrings.
Where Compostable Bags Actually Belong
Certified compostable does not mean a bag will break down anywhere you put it. It needs active composting conditions, heat, moisture, and microbial activity, to start the breakdown process at all. That means an industrial composting facility, a curbside compost program that accepts certified bags, or a home compost bin that meets OK Compost HOME conditions.
Like all organic materials, compostable bags decompose more slowly in landfill conditions where oxygen and moisture are limited. They are not designed for that environment, and they won't behave the same way there as they do in an active compost pile.
Most US municipal composting programs accept BPI certified bags, but policies vary by city. Always check your local program's guidelines before assuming a bag qualifies, and look specifically for the BPI certification requirement when you do.
The bigger takeaway here is simple. Biodegradable is a claim. Compostable, when backed by BPI certification, ASTM D6400 compliance, or TUV Austria marks, is a tested outcome. When you're choosing bags for your kitchen, your yard, or a job site, that difference determines whether the bag actually does what you're buying it to do.
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