To adequately cover these channels with a detachable plate, a manhole cover is required. The majority of the time, manholes are used for maintenance purposes. Manhole coverings will keep unauthorised individuals out and prevent anything or anyone from falling into the hole. A drain cover's main purpose is to protect the environment from contamination. Any chemicals or dangerous materials that go down the drain eventually wind up somewhere usually in the nearest body of water. Rainwater usually flows to the nearest lake, stream, or ocean via drains. It's also safer because a manhole cover won't fall into a hole if it's spun the incorrect direction. Other reasons why corners are a nuisance and why a round shape is preferable may exist.