Which of the following is a consequence of inadequate drainage systems?

Inadequate drainage systems can lead to water accumulation that does not flow away from structures as intended. This accumulation can result in water intrusion, causing damage to foundations, walls, and other structural components. Over time, prolonged exposure to moisture can lead to more severe problems such as mold growth and deterioration of building materials. Effective drainage systems are designed to channel water away efficiently, preventing such damage and ensuring that the environment remains dry and safe. The other options do not directly relate to the effects of inadequate drainage; improvements in water pressure, HVAC performance, or plumbing efficiency are not typically associated with problems arising from ineffective drainage systems.