A landfill is a place where large amounts of waste are left. More rubbish arrives each day, and the landfill takes up more space. The first bottle is pressed beneath other waste. Rainwater flows through the pile and absorbs substances from it, some of which can be toxic. This dirty water, called leachate, can reach groundwater, soil, and streams. It can harm ecosystems and wildlife.
The second bottle travels from a stream into a river and then out to sea. Ocean currents can trap plastic waste in large areas such as the Great Pacific Garbage Patch. Sea birds and other animals may become tangled in the waste or mistake plastic for food. Plastic can make an animal feel full without giving it the food it needs, so it may starve. Plastic toxins can also pass along a food chain: a fish may be eaten by a squid, which may be eaten by a tuna, which people may eat.
Most plastic does not biodegrade. Instead, it breaks into smaller and smaller pieces called microplastics. These pieces are still plastic; they are not material that has biodegraded. They may remain in the sea for a very long time.
The third bottle goes to a recycling plant. There, bottles are pressed into blocks, shredded into small pieces, washed, and melted. The melted plastic becomes raw material that can be used again to make something new.