The answer to 'why is my window water damage' is that it is usually caused by a leak or moisture buildup around the window. This can happen due to poor window sealing, cracks in the frame, or damage to the caulking or weather stripping. Symptoms include visible water stains, mold growth, and wood rot around the window.
To fix window water damage, you'll first need to identify and address the source of the leak. This may involve re-caulking the window, replacing weather stripping, or even repairing or replacing the window itself. If the damage is extensive, it's best to call a professional window repair service to properly diagnose and resolve the issue.