A holding tank, also called a waste water holding tank or black (water) tank, is a container for storing sewage

Sewage

Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...

 in vehicles equipped with toilet

Toilet

A toilet is a sanitation fixture used primarily for the disposal of human excrement, often found in a small room referred to as a toilet/bathroom/lavatory...

s. Vehicles that employ holding tanks include recreational vehicle

Recreational vehicle

Recreational vehicle or RV is, in North America, the usual term for a Motor vehicle or trailer equipped with living space and amenities found in a home.-Features:...

s (RVs), truck

Truck

A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

s (U.S. usage) or lorries (UK usage), railroad train

Train

A train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...

s, boat

Boat

A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...

s, aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

, and even spacecraft

Spacecraft

A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

. The contents are emptied into a dump station

Holding tank dump station

A dump station is a place where raw sewage may be entered into a sanitary sewer system in a safe and responsible way. Dump stations are often used by owners of motorhomes, campervans, recreational vehicle or boats that are equipped with toilet facilities and a sewage holding tank, also known as a...

, which discharges the raw sewage into a sewage treatment

Sewage treatment

Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...

 system.

Holding tank can also refer to a sealed, buried tank used to hold waste from a house or other building. Such a tank is referred to in the U.K. as a cesspit, and as a septic tank

Septic tank

A septic tank is a key component of the septic system, a small-scale sewage treatment system common in areas with no connection to main sewage pipes provided by local governments or private corporations...

 in the U.S.

See also

• Holding tank dump station
  Holding tank dump station
  A dump station is a place where raw sewage may be entered into a sanitary sewer system in a safe and responsible way. Dump stations are often used by owners of motorhomes, campervans, recreational vehicle or boats that are equipped with toilet facilities and a sewage holding tank, also known as a...
  
  
• Passenger train toilets
  Passenger train toilets
  In rail transport, many passenger trains have toilet facilities on board. These are often located at the ends of carriages...
  
  
• Head (watercraft)
  Head (watercraft)
  The head is a ship's toilet. The name derives from sailing ships in which the toilet area for the regular sailors was placed at the head or bow of the ship.-Design:In sailing ships the toilet was placed in the bow for two reasons...
  
  
• Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter
  Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter
  The Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972, commonly called the "London Convention" or "LC '72555" and also barbie abbreviated as Marine Dumping, is an agreement to control pollution of the sea by dumping and to encourage regional agreements...
  
  
• Cesspit