Compostable vs. Biodegradable Straws: What's the Difference?
The two terms are used interchangeably in marketing — and they're not the same thing. Understanding the difference is the difference between a straw that disappears and one that doesn't.
The 60-second answer
Both terms describe materials that break down through biological action — but the conditions, time frames, and end results are very different.
- Biodegradable just means "can be broken down by microorganisms." There's no required time frame, no required conditions, and no required end state. A material that takes 100 years to biodegrade is technically biodegradable.
- Compostable means the material breaks down into non-toxic compost within a defined time frame (typically 90–180 days) under specified conditions (industrial or home composting). Compostability is regulated; biodegradability mostly isn't.
Why the difference matters
"Biodegradable" is a marketing word with no enforceable definition in most jurisdictions. A plastic bag labeled "biodegradable" might break down in 2 years, 200 years, or never under conditions that occur in nature. There's no requirement to specify.
"Compostable" is a regulated word — at least in the U.S. and EU. To be labeled compostable, a product typically must meet one of these standards:
- ASTM D6400 (industrial compost in the U.S.) — requires 90% disintegration within 84 days, biodegradation to non-toxic CO₂ within 180 days under composting facility conditions.
- EN 13432 (industrial compost in the EU) — similar requirements with European-specific testing.
- BPI Certified Compostable — third-party certification in North America that the product meets ASTM D6400.
- OK Compost HOME / TÜV Austria — the much stricter "home compostable" standard. Most products labeled "compostable" do NOT meet this.
Industrial vs. home compostable
This is the most-misleading distinction in eco product marketing. "Compostable" usually means industrial-compostable — meaning the product breaks down only under sustained 50–60°C temperatures, controlled humidity, and active aeration found in industrial composting facilities. It does not mean it'll break down in your backyard pile.
If you live in a city with municipal compost pickup, industrial compost facilities are accessible. If you don't, an "industrially compostable" product going into your home compost or backyard pile will sit there nearly indefinitely. It's no better than plastic in that context.
Straw materials, ranked by compostability honesty
| Material | Biodegradable | Industrial compostable | Home compostable | Marine biodegradable |
|---|---|---|---|---|
| Paper (uncoated) | Yes | Yes | Yes (slowly) | Yes (weeks) |
| Hay / wheat-stem | Yes | Yes | Yes | Yes (weeks) |
| Sugarcane (bagasse) | Yes | Yes | Slowly | Yes |
| PLA (corn-plastic) | Slowly | Yes | No | No |
| PHA (microbial) | Yes | Yes | Yes | Yes (months) |
| Conventional plastic (PP) | No | No | No | No (200+ yrs) |
The take-aways: paper, hay, and PHA are honestly biodegradable across all environments. PLA and sugarcane require industrial composting to break down — they behave like plastic in landfill, ocean, or backyard. Conventional plastic doesn't biodegrade meaningfully under any normal condition.
What to ask before buying a "compostable" straw
- Industrial or home compostable? Most are industrial-only.
- Certified to which standard? ASTM D6400, EN 13432, BPI, OK Compost HOME?
- What happens if it goes to landfill? If the answer is "the same thing as plastic" — and for PLA and most "compostable plastics" it is — you're not getting the benefit you paid for unless your municipality has compost pickup.
- What about marine biodegradation? This is the question almost no manufacturer answers honestly. Paper, hay, and PHA: yes. PLA and most "compostables": effectively no.