The answer to 'drainage system turning brown' is that a brown or discolored drainage system is typically caused by a buildup of organic matter, minerals, or bacterial growth. This can be a common issue with underground drainage pipes or surface drainage features like gutters or downspouts.
Some common symptoms include slow draining, standing water, or a musty odor. Solutions may involve cleaning out the drainage system, treating it with a disinfectant or enzyme cleaner, or in some cases replacing damaged pipes or components. In many cases, this can be a DIY project, but for more complex issues it's best to call in a professional landscaping or plumbing contractor.