The information on housing units by type of sewage disposal system may be classified as follows:
1. Empties into a piped system connected to a public sewage disposal plant.
2. Empties into a piped system connected to an individual sewage disposal system (septic tank, cesspool).
3. Other—toilet empties into an open ditch, a pit, a river, the sea, and so forth.
4. No disposal system.