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.
Indian River Lagoon
In 2016, there were an estimated 300,000 septic tanks in the five-county area bordering the Lagoon. At one time, sewer plants were worse polluters. In 1986, there were 46 sewer plants along the lagoon. They discharged about daily into the estuary. The state ended most sewer plant pollution by 1995.
In 2018, lagoon health is better near ocean inlets. Pollution is worse in areas near no inlets, such as the Mosquito Lagoon, North IRL, and the Banana River.