Your ‘recycled polyester’ leggings are not as sustainable as you think
- Written by: Caroline Swee Lin Tan, Associate Professor in Fashion Entrepreneurship, RMIT University
Recycled polyester activewear and swimwear are now everywhere. Major global brands sell leggings, swimsuits and puffer jackets with labels that claim they’re “made from recycled plastic bottles”. Millions of people buy these products believing they’re making a more sustainable choice.
The logic seems straightforward. Turning existing plastic waste into clothing is better than landfill.
However, the story is more complicated. What looks like circular recycling is often a one-way trip to landfill, revealing how recycled fabrics can mask environmental problems rather than solve them.
Where the plastic really comes from
Despite images of ocean clean-ups in glossy marketing, most recycled polyester used in fashion doesn’t come from marine waste or even old clothing. Instead, it comes from PET (polyethylene terephthalate) drink bottles.
The most recent Materials Market Report shows that about 98% of recycled polyester comes from plastic bottles. Textile-to-textile recycling accounts for less than 1% of the supply. And activewear is the single largest apparel use of recycled polyester in fashion supply chains.
Consequently, many garments marketed as “sustainable” rely on plastic taken from an effective recycling system, rather than addressing fashion’s own textile waste.
How PET bottle recycling works
PET, the plastic used to make drink bottles, is one of the most successfully recycled plastics. Decades of investment in collection, sorting and reprocessing have made bottle-to-bottle recycling possible in many countries.
This works because PET bottles are uniform and collected in large volumes. There is also strong demand for recycled, food-grade material. Research shows PET can be recycled many times without losing quality, as long as it stays within the bottle system.
When PET stays a bottle, it remains a high-value material.
What happens when bottles become clothes
That recycling loop breaks when PET becomes textile fibre. To make clothing, bottles are shredded and melted into polyester yarn, then dyed, blended and sewn into garments. Fibre blends, especially polyester mixed with elastane, make textile-to-textile recycling difficult.
Most textile recycling systems are mechanical and limited in scale. They struggle with blended fabrics. As a result, most polyester clothing can’t be recycled and ends up in landfill or incineration.
In circular economy terms, bottle-to-garment recycling is downcycling. Material quality drops, and future use is limited.
There’s also another environmental cost consumers rarely hear about. Mechanical recycling shortens polymer chains, resulting in more fragile, “hairy” fibres that snap easily during domestic washing. Studies show synthetic clothing sheds microplastic fibres, making it a major source of marine pollution.
Research suggests recycled polyester may shed more microfibres than virgin polyester (made new from fossil fuels rather than recycled from plastic).
Testing by Çukurova University in Turkey found recycled polyester shed 55% more microfibres than virgin polyester. These fibres were smaller and more brittle, increasing the likelihood they travel further in aquatic environments and enter our food chain.
Are there any benefits to recycled polyester?
Compared with virgin polyester, recycled polyester usually uses less energy and produces fewer greenhouse gas emissions during manufacturing. This is why initiatives like the 2025 Recycled Polyester Challenge have pushed brands to commit to sourcing 45% to 100% of their polyester from recycled sources.
However, these schemes have hit a major roadblock: the lack of technology to recycle old clothes. Because the infrastructure for textile-to-textile recycling doesn’t yet exist at scale, brands have been forced to “borrow” bottles to meet their targets.
This highlights the tension between immediate technical needs and genuine sustainability. The next step is building the actual technology for circularity, so brands can move past the trap of greenwashing.
A recycling ‘dead end’
When bottles become garments, they leave one of the few recycling systems that works well and enter another that can’t yet recycle most clothing. This shift is becoming a major legal flashpoint. The European Union’s 2030 Vision for Textiles mandates that by 2030, all textile products on the market must be durable, repairable, and made largely of recycled fibres.
As brands scramble to meet these targets, a global supply crunch is emerging. With new EU packaging regulations coming into effect from August 12 2026, companies will be required to make packaging recyclable and prepare for future recycled content requirements.
As a result, the beverage industry is fighting to keep its own plastic. They argue fashion is “leaking” high-quality recycled PET out of a closed loop to mask its own lack of infrastructure.
This highlights the core problem: recycling should reduce waste overall, not simply move it between industries.
Recycled polyester only works when clothes become new clothes. While investment is growing, the fashion industry’s reliance on bottles is a distraction. Until the fashion industry solves its own waste crisis rather than borrowing from the beverage sector, turning bottles into clothing remains a one-way path to waste.
Currently, the most sustainable outcome for a plastic bottle is to remain a bottle.
Read more: Here’s how using more recycled plastic could ease the pain of oil shocks
Authors: Caroline Swee Lin Tan, Associate Professor in Fashion Entrepreneurship, RMIT University
