Septic tanks can emit unpleasant odors when malfunctioning or not regularly maintained. These odors can seep into the house through cracks or gaps in the plumbing system or foundation, causing an unpleasant smell within the living space. Common reasons for septic tank stinks include improper waste disposal, overloading, clogged or damaged components, inadequate ventilation, and high water table levels. To resolve the issue, regular septic tank pumping, leach field inspection, and maintenance are crucial, as well as addressing any underlying problems such as excessive chemical use or plumbing leaks.