drain

Drains are channels or pipes that carry off water or other liquids from a surface, area, or device. As a verb, drain means to remove liquid from something, often by gravity or suction. The term is used in plumbing, civil engineering, hydrology, and electronics.

In plumbing, a drain is the lower end of a pipe network designed to discharge wastewater and prevent overflow. A drain typically connects to a trap, which seals odors, and to a vent to equalize pressure. Cleanouts provide access for maintenance. Common drain types include floor drains, sink drains, shower drains and roof drains, often integrated with a sewer or septic system.

Landscape and subsurface drainage seek to remove excess water from soil or surfaces to prevent damage and erosion. Techniques include French drains (perforated pipes in a gravel trench with a filter), trench or channel drains, perforated drain tiles and surface swales. Proper drainage requires assessment of slopes, soil permeability, and water sources.

In electronics, the term drain designates the output terminal of a transistor or diode where current flows out of the device, as in a MOSFET or JFET. The opposite terminal is the source or anode, depending on device type.

Maintenance involves regular clearing of hair, grease, and debris from drains; using strainers; avoiding pouring oils down drains; and scheduling professional inspections in older buildings. Clogs or leaks can lead to water damage, mold, and higher utility costs.