Bio-based and compostable plastic
Polylactic acid (PLA)
PLA is a plastic made from plant sugars, often sold as 'plant-based', 'compostable' or 'biodegradable'. It's still plastic, it usually needs industrial composting that UK households don't have, and it doesn't belong in the plastic recycling.
By PlasticFreeHome Research Team · Not yet reviewed by an editor · Updated 21 October 2026
- Also called
- plant-based plastic, bioplastic, compostable plastic, corn starch plastic
- Recycling code
- 7 (Other)
- Type
- Bio-based and compostable plastic
- Found in
- 'compostable' cups and cup linings, pyramid tea bags, disposable cutlery and straws, fruit and veg packaging, 3D printing filament
- Heat
- Low heat resistance compared with most plastics, which is why hot-drink lids are often made of something else.
- Recycling in the UK
- Don't put it in plastic recycling. Only use a food-waste caddy or home compost if the item is certified and your council or compost says so; otherwise general waste.
What it is
Polylactic acid (PLA) is a plastic made by fermenting plant sugars, usually from corn, sugarcane or cassava, and joining the resulting lactic acid into long polymer chains. It's marked 7 ("other") in the recycling triangle, if it's marked at all.
Is PLA plastic?
Yes. What a plastic is made from doesn't change what it is: PLA is a synthetic polymer, just like fossil plastics. WRAP, which runs the UK Plastics Pact, says the term "plastic-free" shouldn't be used for compostable plastics even if they're 100% plant-based. Under our definition PLA always counts as plastic. See is PLA plastic?
"Compostable" and "biodegradable"
- Compostable should mean the item is certified to break down under defined conditions. For most PLA that means industrial composting, at temperatures a garden heap doesn't reach. Home composting is a separate, gentler standard, and products certified only for industrial composting may not break down at home.
- Biodegradable on its own isn't a meaningful promise: it doesn't say where, how fast or into what.
- Plant-based describes the raw material, not what happens at the end of life. Not all plant-based plastics are compostable, and not all compostable plastics are plant-based.
Where you'll meet it
Pyramid tea bags, "compostable" coffee cups (often a paper cup lined with PLA), cutlery and straws, and some fruit and salad packaging. See how to tell if your tea bags contain plastic.
What to do with it
- Not in the plastic recycling. PLA can contaminate the recycling of conventional plastics.
- Food-waste caddy: only if your council explicitly accepts certified compostable items. Many don't.
- Home compost: only if it's certified for home composting.
- Otherwise: general waste.
The best option is usually reuse: takeaway cups → reusable, tea bags → loose leaf.
Related guides
Sources
- WRAP / UK Plastics Pact (2025), Considerations for compostable plastic packaging — compostable plastics are still plastics; home and industrial composting are different
- WRAP (2022), Polymer choice and recyclability guidance — which plastics are recyclable in the UK, and why PVC and polystyrene are not
Swaps involving PLA
Plastic tea bags → loose-leaf or plastic-free bags
Many tea bags are sealed with polypropylene or made of plastic mesh. Hot water plus plastic, several times a day; how much reaches your cup is still debated.
High priority · about 120 g of plastic a year
Takeaway coffee cups → reusable steel cup
Paper cups are lined with plastic and topped with a plastic lid, and they hold drinks at 80°C or more.
High priority · about 500 g of plastic a year