Fire Hydrants are used by the fire department where there is a municipal water supply.

THEY’RE EVERYWHERE, so common that we scarcely notice them. They’re ignored, uncelebrated, the butt of jokes about peripatetic dogs, yet they play a vital role in public safety. In their 200-year history, fire hydrants have saved countless lives and billions of dollars.

Firefighting existed before the hydrant and the idea of getting the wet stuff onto the red stuff is very old. The inventor of the first device that we'd recognize today as a fire hydrant can't be told, because the hydrant was developed over a period of many years by many people.

The first hydrants were used for public water supply from the earliest municipal water systems. They resembled faucets and were at best suited for the bucket brigade method of firefighting. Prior to municipal water systems, there were other means to provide water in the event of a fire.

In colonial America cisterns were used to store water for early fire fighting purposes, and these continued to be used even after the introduction of the hydrant in many cities. Fire cisterns are underground tanks or structures that hold water to be pumped for firefighting use.

The term "fire plug" dates from the time when water mains were made from hollowed out logs. The fire company (usually volunteers) would head out to the fire, dig up the cobbles down to the main, then bore a hole into the main so that the excavation would fill with water which they could draft using their pumper. When finished fighting the fire, they'd seal the main with -- you guessed it -- a "fire plug". The next time there was a fire in the neighborhood, they'd dig up the plug and not have to cut into the main.

Cast iron would come to replace wooden water mains, and when cast iron started becoming popular, branched fittings were placed on the mains at intervals, much like today's fire hydrants. These were like underground hydrants which could draw water from the water mains in a crude fashion.

In the 1930s, manufacturers began to produce “traffic hydrants,” designed to break off on impact without damaging the main valve. (Contrary to what we see in the movies, knocking over a hydrant does not usually produce a geyser.) There have been countless other refinements in materials and manufacturing techniques, but the design of fire hydrants has been remarkably consistent over the years.

Today, fire hydrants are constructed of cast iron, and water mains are constructed of ductile iron, cast iron, or plastic underground pipe. With these types of fire hydrants and piping systems, pressures and pipe diameters have greatly increased. Because of greater pressures and larger diameters, more effective water supplies can be established to fight fires. Although the days of wooden fire mains and wooden plugs are gone, many people still refer to the fire hydrant as a fire plug. The hydrant / plug does not appear to be headed for obsolescence any time soon.

The term drafting water refers to the use of suction to move a liquid such as water from a vessel or body of water below the intake of a suction pump. We have to take our water with us and draft water from a porta-tank to extinguish a fire in a rural area. Once we use the water on the trucks we will draft water from a pond or lake to get additional water to use at the fire. The fire department pump creates a partial vacuum (a "draft") and the atmospheric pressure on the water's surface forces the water into the pump, usually via a rigid pipe (sometimes called a "dry hydrant") or a semi-rigid "hard suction hose".