A fire hose is a high-pressure hose used to carry water or other fire retardant (such as foam) to a fire to extinguish it. Outdoors, it is attached either to a fire engine or a fire hydrant. Indoors, it can be permanently attached to a building's standpipe or plumbing system. It was invented by Hero of Alexandria in the basis of Ctesibius' double action piston pump. The usual working pressure of a fire hose can vary between 8 and 20 bar (800 and 2,000 kPa; 116 and 290 psi), while its bursting pressure can be up to 83 bar (8,300 kPa; 1,204 psi). After use, a fire hose is usually hung to dry as standing water that remains in a hose for an extended period of time can deteriorate the material and render it unreliable or unusable. As such, the typical fire station often has a high structure to accommodate the length of a hose for such preventative maintenance. On occasion, fire hoses are used for crowd control (see also water cannon), including most notably by Bull Connor in Alabama against civil rights protestors in 1964 While still a common practice in many countries, it is no longer used in the U. S