Which statement is true regarding septic tanks?

The statement that all seams and drain holes must be watertight is true because septic tanks are designed to contain wastewater safely and prevent any leaks from entering the surrounding soil or groundwater. A watertight structure is critical to ensure that contaminants do not escape from the septic system into the environment, which could pose serious health risks and lead to contamination of water sources. Seams must be properly constructed and sealed to maintain the integrity of the tank. Additionally, any drain holes should be properly installed and secured to prevent unwanted leakage. This watertight requirement is a fundamental aspect of septic system safety and functionality.