The principles of interior drainage, also known as an interior drainage system, include:

• Water capture: The first principle is to capture water that infiltrates the basement or around the house's foundations. This can include rainwater, snowmelt, or any other source of moisture.
• Controlled evacuation: Once water is captured, the interior drainage system directs it in a controlled manner to a specific outlet point, usually a sump pit or a lift pump.
• Flood prevention: The primary goal of interior drainage is to prevent floods and water damage by preventing water accumulation in the basement. This helps protect the structure of the house and its contents.
• Moisture protection: By effectively removing water and moisture from the basement, the interior drainage system helps maintain a dry environment, thereby reducing the risk of mold, mildew, and moisture-related issues.
• Use of specific components: Interior drainage systems typically include elements such as perforated pipes, drainage gravel, a vapor barrier membrane, and optionally a sump pump to ensure efficient operation.
• Periodic maintenance: To ensure the system operates properly, regular maintenance is essential, including pipe cleaning, checking the sump pump, and replacing faulty components.
• Adaptation to specific needs: The design of the interior drainage system should be tailored to the specific needs of the house and the region, taking into account the groundwater level, local climate, and other environmental factors.

In summary, interior drainage is an essential system to prevent water and moisture-related problems in a house's basement, thereby helping to maintain a dry and healthy environment.