Wetlands act as kidneys for rivers, cleaning out rubbish and pollutants from water. Larger wetlands can take longer to walk through but remove more pollutants. Wetlands go by many names like swamp, bog, fen, marsh, and muskeg. A man-made wetland is constructed by humans to filter stormwater, while a natural wetland occurs without human involvement. Constructed wetlands are meant to filter out pollution and contaminants from water.