Blocked drainage occurs when water cannot flow freely through pipes due to obstructions. Common causes include the buildup of debris, such as hair, grease, or food particles, which can create clogs. This blockage can lead to slow drainage or even complete stoppage, causing water to back up in sinks, showers, or toilets. When drainage is blocked, it can result in unpleasant odors and potential water damage. Regular maintenance, such as using a drain snake or plumber's snake, can help clear minor clogs. In severe cases, professional assistance may be required to restore proper drainage and prevent further issues.