Septic tank
A septic tank is an underground chamber made of concrete, fiberglass or plastic through which domestic wastewater (sewage) flows for basic treatment. Settling and anaerobic processes reduce solids and organics, but the treatment efficiency is only moderate (referred to as "primary treatment"). Septic tank systems are a type of simple onsite sewage facility (OSSF). They can be used in areas that are not connected to a sewerage system, such as rural areas. The treated liquid effluent is commonly disposed in a septic drain field which provides further treatment. However, groundwater pollution may occur and can be a problem.
Cesspit
On June 1, 2011, two teenagers from Farmingville in Long Island, New York, drowned after becoming overwhelmed by fumes and trapped in a backyard cesspool measuring 16-feet deep. The collapsing cesspools were mostly due to older cesspools built with brick or cinder block. These structures weakened over their lifespan leading to increased risk of collapse. Newer cesspools are cast concrete which dramatically decrease any risk of collapse. All new construction in areas without waste sewer systems use these new precast cesspools. In addition, cast concrete cesspools are used commonly in commercial construction for storm water collection.