Septic tanks are part of the wastewater disposal system on a property. The tanks are designed to remove solids from wastewater that is disposed through a home’s drains, including the waste from the kitchen, laundry, and bathrooms. The solids that settle at the bottom of the septic tank create sludge. They may also float to the top of the water and form a layer of scum. The effluent is then transported to a soil absorption site.