How Long Does it Take for Waste to Decompose?

It can take between 20 and 500 years for plastic to decompose, sometimes even thousands of years. Certain plastics don’t fully break down either, they just degrade into smaller particles. Plastic types such as PET (polyethylene terephthalate) don’t biodegrade naturally and require specific conditions with UV light, so won’t decompose in landfill.

The type of plastic, its structure, and environmental factors all affect how long it takes plastic to decompose. Biodegradable plastics offer potentially quicker decomposition times. The plant-based hydro-biodegradable plastic polylactic acid (PLA) takes up to 90 days to decompose. However, conditions must be perfect in commercial composting facilities at high temperatures, otherwise, it may take as long as traditional plastic.

How long does it take for a plastic bottle to decompose?

Plastic bottles can take up to 450 years to decompose. This is because most plastic bottles are made from polyethylene terephthalate (PET), which is a non-biodegradable plastic. It’s a strong and lightweight material but it’s made with chemicals that bacteria can’t consume, so it takes a long time to degrade.

As most plastic bottles decompose in landfill they break down into nanoplastics that can remain in the environment. Many of these tiny plastic particles end up in our oceans, waterways, and air. It pollutes the environment and negatively affects wildlife, which is just another reason to recycle plastic waste.

How long does it take for a plastic bag to decompose?

It takes around 20 years for a plastic bag to decompose. However, some may take hundreds and even up to 1,000 years to completely break down. Most plastic carrier bags are made of either high-density polyethylene (HDPE) or low-density polyethylene. These are both organic polymers but are nonbiodegradable plastics.

As plastic bags are lightweight and thin they may decompose in as little as a decade or two in the right conditions. Even when they do decompose the plastic particles left behind may continue to pollute the environment.

Glass doesn’t decompose naturally, and it may take up to 4,000 years to break down. It might even take up to a million years for glass to decompose, as glass bottles, jars, and vases from millennia ago are still found today and displayed in various museums.

Even though glass may break easily enough if dropped there are no microorganisms on the planet that consume glass materials. The good news is that glass is infinitely recyclable and can be reused and repurposed into new glass bottles, jars, and other products. Recycling glass is essential and waste glass should never go to landfill.

Cardboard can decompose within three months in the right conditions. If it’s shredded, soaked in water, and exposed to oxygen and the elements then it could even break down in two months. For this reason, waste cardboard can be composted and used as garden mulch, as long as there are no contaminants.

Any cardboard waste sent to landfill may take years to decompose though. When cardboard sheets are stacked up and tightly packed together it takes longer for them to break down. Most cardboard is recyclable and reusable. Cardboard should be recycled or shredded and mulched or composted rather than sent to landfill.

Wood is an organic material that decomposes naturally but how long it takes depends on the type of product and its size. For example, wood chips can decompose in three to six months as they’re small and made from natural wood. Large items of lumber furniture may take up to 15 years to decompose as they’re bigger and may contain chemicals.

Lots of wood products include contaminants such as paint, glue, and other chemicals. Their presence affects the rate of decomposition and whether such items can be composted or not. Recycling and reusing wood is better for the environment where possible. How long it may take wood to decompose based on its type:

• Plywood – one to three years
• Lumber – 10 to 15 years
• Stumps and branches – 50 to 10 years (if whole)