Every building that has plumbing fixtures and drainage piping must, by law, have a building drain that is connected to a sewer.
Building drains are designed to receive discharge from various drainage pipes inside any building, including soil and waste pipes. While soil pipes discharge fecal matter, other waste results from the use of fixtures, appliances, and certain areas within a building. The building drain is where the lowest piping of the drainage system is located and it extends five feet (1,524 m) beyond the exterior walls of the building.
There are various different types of sewers, but the ideal is for all buildings to be connected to a public sewer, for example, one that is owned by New York City (NYC). This would either be a sanitary sewer or building drain that only conveys sewage or a combined sewer that conveys sewage as well as stormwater and other drainage material.
If it is not feasible for a building drain to connect to a public sewer, it must be connected to a private sewer. Alternatively, a private sewage disposal system has to be provided. In the context of the NYC Plumbing Code 2014, the classification of plumbing fixtures for water supply and drainage refers to fixtures found in:
- Residences including houses and apartments.
- Toilets in the rooms of hotels and motels used by guests.
- Similar installations in other buildings where fixtures are intended for the use of individuals or families.
Private sewers are designed and constructed in accordance with the Plumbing Code and, once approved by the City’s Department of Environmental Protection (DEP), discharges into an approved outlet that links to a waste treatment plant.
If there is an accessibility problem, it is sometimes possible to extend public sanitary or combined sewers so that they can be connected to building drains. The DEP determines whether this is feasible.
Storm sewers are designed specifically to remove stormwater and cannot be linked to a sanitary system. However, if separate sanitary and storm drains are installed on one property, these may be laid side-by-side in a single trench.