How long does it take for plastic bags to decompose? A plastic bag can take from 15 to 1,000 years to break down, depending on environment. In a landfill, kept away from the environment that would help them biodegrade more easily, paper bags don’t do much better.
Plastic bags don’t biodegrade, but they can break down through photo degradation. When photo degradation, decomposition through exposure to light, happens, the bag breaks down into small, toxic particles.