The answer to 'drainage system overgrown' is that a common cause is excessive plant growth and debris buildup in the drainage system. Symptoms include standing water, flooding, and poor drainage. Solutions include clearing the drainage system, trimming or removing overgrown vegetation, and ensuring proper water flow.
In many cases, a simple DIY approach of clearing leaves, sticks, and other debris from the drainage system can resolve the issue. However, if the problem is more severe, such as a clogged pipe or damaged drainage infrastructure, it's best to call in a professional landscaper or drainage specialist to properly diagnose and fix the problem.