The answer to 'why is my drainage system disease' is that your drainage system may be clogged or damaged, leading to poor water flow and potentially breeding grounds for pests and bacteria. Common causes include debris buildup, broken pipes, and improper installation. Symptoms can include standing water, foul odors, and visible mold or algae growth.
To address a drainage system issue, you'll first want to inspect the system for any obvious blockages or damage. This may involve removing debris from gutters, downspouts, and surface drains. If the problem persists, you may need to hire a professional landscaper or plumber to assess the underground drainage pipes and recommend solutions like pipe relining, replacement, or improved grading and landscaping.