ELI5: Explain Like I'm 5

Constructed wetland

Constructed wetland is an area of land that is made to look like a real wetland. These wetlands are made with plants, rocks and gravel that help clean the water as it flows through them. The plants help to filter out pollutants and the gravel and rocks provide a place for bacteria to break down the pollutants. This makes the water cleaner and helps to prevent pollution in rivers and lakes.