Landfills are harmful
Dropped into a landfill, some materials are broken down for hundreds and thousands of years, and the composition of others does not allow their decomposition at all. For example, many types of plastic just break into smaller pieces, but they do not disappear. When they fall into nature, these particles enter the food chain as the animals swallow them along with the rest of their food. So the incorrectly discarded bottle of water turns into a pebble that turns entire ecosystems.