A fire hydrant is an active fire protection measure, and a connection point by which firefighters can tap into a water supply.The invention of a post- or pillar-type fire hydrant is generally credited to Frederick Graff, Sr., chief engineer of the Philadelphia Water Works around 1801. It had a combination hose/faucet outlet and was of "wet barrel" design with the valve in the top. It is said that Graff held the first fire hydrant patent, but this cannot be verified because an 1836 fire in the US Patent Office destroyed many patent records.

The user attaches a hose to the fire hydrant, then opens a valve on the hydrant to provide a powerful flow of water, on the order of 350 kPa (50 lbf/in²) (this pressure varies according to region and depends on various factors including the size and location of the attached water main). This user can attach this hose to a fire engine, which can use a powerful pump to boost the water pressure and possibly split it into multiple streams. One may connect the hose with a threaded connection, instantaneous "quick connector" or a Storz connector.

A fire hydrant is an active fire protection measure, and a connection point by which firefighters can tap into a water supply.The invention of a post- or pillar-type fire hydrant is generally credited to Frederick Graff, Sr., chief engineer of the Philadelphia Water Works around 1801. It had a combination hose/faucet outlet and was of "wet barrel" design with the valve in the top. It is said that Graff held the first fire hydrant patent, but this cannot be verified because an 1836 fire in the US Patent Office destroyed many patent records.

The user attaches a hose to the fire hydrant, then opens a valve on the hydrant to provide a powerful flow of water, on the order of 350 kPa (50 lbf/in²) (this pressure varies according to region and depends on various factors including the size and location of the attached water main). This user can attach this hose to a fire engine, which can use a powerful pump to boost the water pressure and possibly split it into multiple streams. One may connect the hose with a threaded connection, instantaneous "quick connector" or a Storz connector.