Glass is generally considered a more environmentally friendly alternative to plastic. It's very strong, easy to recycle, and doesn't contain any harmful toxic chemicals. But it isn't perfect.
For one thing, glass is not biodegradable, even though it is made from natural minerals.
But that doesn't mean that glass is bad for the environment. It isn't, providing it's used and disposed of properly.
Below, you will learn why glass doesn't decompose, how and where to recycle it, and why it's better for the environment than plastic.
No, glass is not biodegradable or compostable.
Materials can only be considered to be biodegradable if they can be broken down naturally by living organisms. This isn't possible with glass.
Glass isn't biodegradable because there are no bacteria, microorganisms, or other biological processes capable of digesting it or producing enzymes to break it down.
This is because of chemical changes that take place during the manufacturing process.
Glass is made by melting silicon dioxide (SiO₂), which is the major constituent of sand, at very high temperatures.
During this process, the raw material undergoes a chemical transformation that creates a highly stable chemical structure that doesn't react with acids or water ("Aqueous alteration of silicate glass: state of knowledge and perspectives", Gin et al, 2021).
So glass will never biodegrade, but it does erode and break down into smaller particles very slowly over time.
A modern glass bottle could take anywhere between 4000 to 20,000 years to decompose.
This estimate is based on an erosion rate of 3–4 µm/year (micrometers per year), increasing to 5–20 µm/year over decades ("Insights into long term glass corrosion mechanisms from the Ballidon experiment", Thorpe et al, 2025)
Glass wasn't designed to break down easily, and it doesn't. That's why we're finding glass artifacts from ancient Egypt still intact.
Studies on ancient glass artifacts show that they undergo minimal structural changes even after millennia, which demonstrates that glass is resistant to biological decay ("A review of glass corrosion: the unique contribution of studying ancient glass to validate glass alteration models," Roberta Zanini et al, 2023).
That's why recycling glass bottles is so important.
Glass is both recyclable and reusable.
Glass is a material that can be recycled repeatedly without any loss in quality. Recycling glass helps conserve energy and resources, since it takes 10-15% less energy to melt down recycled glass than it does to create new glass from scratch (Energy Implications of Glass-Container Recycling, NREL).
The only problem is that not all types of glass can be recycled together. For example, the glass used in light bulbs, mirrors, ovenware, Pyrex, and window glass is produced differently and should not be put in the same container as your glass bottles and glass jars.
Glass containers such as these, which can't be added to other recycled glass, can instead be “downcycled” into other products such as fiberglass insulation or sandblasting grit.
Therefore, it’s important to check with your local recycling center to see what types of glass they accept.
You can recycle glass by leaving it for curbside collection or taking it to designated drop-off points, or your local recycling center.
Recycling glass helps to save energy and precious natural resources, and reduces carbon dioxide emissions and pollution. So don't just throw it in the trash.
Most local authorities in urban areas accept glass via curbside recycling programs. Some areas require that you separate the glass by color and leave brown, green, and clear items separately.
If you live in a bottle bill state (currently California, Connecticut, Hawaii, Iowa, Maine, Massachusetts, Michigan, New York, Oregon, and Vermont), you can return your empty glass bottles to the retailer and get money back. Current rebates range between 5c and 15c per bottle. Helping the planet is even better when you get paid to do it!
If neither of these options works for you, take your unwanted glass to a designated drop-off point. Use the Earth911 search to find the closest facility to where you live.
Finally, if your glass is still in good condition, consider reusing it instead. Glass jars with a lid need not be thrown away; they have many other uses around the house. Use them for storing food, liquids, or any other items you can think of.
Broken glass can be recycled. However, some local authorities and recycling centers do not accept broken glass because it can be dangerous for workers.
It's also difficult for the recycling facility to sort it into colors.
For these reasons, you shouldn't put any broken glass in the recycling bin with your other glass bottles and containers.
Recycled glass can still be used for various purposes, even if it is broken, so there is no need for it to end up in a landfill.
The best thing to do is to collect up any broken glass (using a suitable pair of protective gloves) and then put it in a strong cardboard box. Then contact your local recycling center and see if they will accept it. If not, they can usually recommend someone who will.
Glass is still considered eco-friendly. There are several good reasons for this, including the following.
Glass is a good option for those looking to live a zero-waste lifestyle because it can be easily cleaned and reused almost indefinitely.
That's one of the reasons it's popular for products such as eco-friendly glass drink bottles, because, unlike plastic bottles, they can last a lifetime.
Glass waste takes up space in landfills and has the potential to harm wildlife.
Only 1/3 of glass is currently recycled, and 9.2 million tons goes into landfill in the USA annually, according to the Glass Recycling Foundation (GRF). Since it doesn't decompose, any landfilled glass is likely to remain there indefinitely.
Then there's the glass that isn't disposed of at all. 7.2% of all litter is glass ("2020 NATIONAL LITTER STUDY", Keep America Beautiful). When it gets broken, sharp edges can harm children, pets, and wildlife.
Glass litter certainly isn't as bad as plastic (which is 38.6% of all litter and far more harmful), but it is still a hazard if we don't deal with it in the right way.
No, glass is certainly better for the environment than plastic.
Unlike glass, not all plastic is recyclable, and many types of plastic are rarely recycled, even when it is possible. Plastic also cannot be endlessly recycled like glass can.
Worse still, when plastic breaks down, it contaminates the natural environment, clogs up the ocean, kills animals and marine life, and gets into our food and water supplies. The plastic pollution statistics bear this out.
Glass may not be perfect, but the environmental impact of plastic is far worse.
There are biodegradable alternatives to glass, including transparent wood, bamboo-based materials, and plant fiber composites.
Not all of these options are mainstream, and some may never be. Currently, they are at various stages of development and commercialization, but all aim to provide glass-like functionality with a reduced environmental footprint
The table below shows how the various glass alternatives compare.
| Material Type | Biodegradability | Main Ingredients | Example Use Cases |
|---|---|---|---|
| Transparent wood composites | Fully biodegradable | Wood, egg whites, rice extract | Windows, screens |
| Transparent bamboo materials | Partially/mostly biodegradable | Bamboo, sodium silicate, polymers | Indoor panels, lighting |
| Flax fiber composites | Biodegradable | Flax fibers | Bottles, packaging |
| Organic eutectic glasses | Potentially biodegradable | Organic molecules | Various (research stage) |
