It’s now as easy to wear a plastic water bottle as to drink out of one. The appeal for brands to use recycled plastic water bottles to make their gear is simple: recycling, they say, is a more earth-friendly alternative. And though bottles aren’t the only form of plastic being recycled into clothing (old fishing nets are another common contender) they are one of the most popular. But is this seemingly ubiquitous material really the sustainability solution it’s cracked up to be?

In answering that question, it helps to zoom out a bit to look at the fashion industry as a whole. When plastic water bottles are turned into fabric, the result is polyester, aka the most commonly used textile fiber in the world. According to a report from Textile Exchange, polyester made up about 52 percent of fibers produced globally in 2019, and only 14 percent of that total was made from recycled materials.

“Using recycled plastic bottles is an improvement against using virgin polyester materials,” says Textile Exchange director of standards Ashley Gill. It’s not hard to see why. Both polyester and plastic bottles are derived from climate change-causing fossil fuels, so reducing demand for virgin materials is an obvious boon.