Damp Basement - The source of your damp basement problem could be a water leak or high humidity. Both can lead to mold, mildew, or other biological growth. Depending on the severity, conditions can lead to rot, structural damage, premature paint failure, and a variety of health problems. Water can seep into your house from the outside through a leak in the foundation, or small gaps around windows or doors. Water can also come from inside your house from a leaking water pipe, toilet, shower or bathtub. High indoor humidity caused by normal activities of everyday living, such as showering, cooking, and drying clothes, can also be a source of your problem. A damp basement is commonly caused by moisture migrating through a concrete foundation. There may not be a sign of any leak or standing water, but the moisture evaporates, increasing indoor humidity. Another common cause is condensation on the cold concrete walls and floors during humid months.