structural:expansion, linguistic:paraphrasing
Design and function

The majority of filling stations are built in a similar manner, with most of the fueling installation underground, pump machines in the forecourt and a point of service inside a building. Single or multiple fuel tanks are usually deployed underground. Local regulations and environmental concerns may require a different method, with some stations storing their fuel in container tanks, entrenched surface tanks or unprotected fuel tanks deployed on the surface. Fuel is usually offloaded from a tanker truck into each tank by gravity through a separate capped opening located on the station's perimeter. Fuel from the tanks travels to the dispenser pumps through underground pipes. For every fuel tank, direct access must be available at all times. Most tanks can be accessed through a service canal directly from the forecourt.

Older stations tend to use a separate pipe for every kind of available fuel and for every dispenser. Newer stations may employ a single pipe for every dispenser. This pipe houses a number of smaller pipes for the individual fuel types. Fuel tanks, dispenser and nozzles used to fill car tanks employ vapor recovery systems, which prevents releases of vapor into the atmosphere with a system of pipes. The exhausts are placed as high as possible. A vapor recovery system may be employed at the exhaust pipe. This system collects the vapors, liquefies them and releases them back into the lowest grade fuel tank available.

The forecourt is the part of a filling station where vehicles are refueled. Gasoline pumps are placed on concrete plinths, as a precautionary measure against collision by motor vehicles. Additional elements may be employed, including metal barriers. The area around the gasoline pumps must have a drainage system. Since fuel sometimes spills onto the pavement, as little of it as possible should remain. Any liquids present on the forecourt will flow into a channel drain before it enters a petrol interceptor which is designed to capture any hydrocarbon pollutants and filter these from rainwater which may then proceed to a sanitary sewer, stormwater drain, or to ground.

If a filling station allows customers to pay at the dispenser, the data from the dispenser may be transmitted via RS-232, RS-485 or Ethernet to the point of sale, usually inside the filling station's building, and fed into the station's cash register operating system. The cash register system gives a limited control over the gasoline pump, and is usually limited to allowing the clerks to turn the pumps on and off. A separate system is used to monitor the fuel tank's status and quantities of fuel. With sensors directly in the fuel tank, the data is fed to a terminal in the back room, where it can be downloaded or printed out. Sometimes this method is bypassed, with the fuel tank data transmitted directly to an external database.