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Stories from DEP is a collection of feature articles
published in DEP's internal newsletter, Weekly Pipeline.
This article was originally published August 24, 2010.

It's a High-Pressure Job but 200 Years Later City Hydrants Still Keeping City Safe

New York City’s 109,000 fire hydrants have recently gotten a lot of attention due to this summer’s scorching heat. Although their main purpose is to provide a readily available water supply to fight fires, New Yorkers have sometimes been using them to cool off, and often in ways that endanger public safety. Where do these ingenious devices come from?

The first “hydrants” were simply large containers filled with water, placed in strategic locations within a city to be used for fire suppression. As cities grew, so too did their need to obtain a constant and reliable source of water to combat fires. It started out by tapping in to the New York City’s earliest water mains, which consisted of wooden logs fashioned into pipes buried beneath the city’s streets. When a fire broke out, volunteer firefighters would unearth these mains and drill a hole in them, allowing the water to flow out. Water was then pumped out of the system to combat the fire. When the fire was finally extinguished, they would seal the hole with a “fire plug,” a term that to this day is sometimes used to refer to fire hydrants. The locations of these fire plugs were marked in case of future need.

Although there’s not a lot of historical documentation on hydrant development, by the 1700s firefighters began carrying standpipes (outlets) which were inserted into the valves, and valves replaced the wooden plugs in some parts of the world. Unfortunately, some advancements were spurred by disasters: new water mains with predrilled holes and plugs that rose above ground level were installed throughout London when fire destroyed three-quarters of the city in 1666. New York City’s first above-ground hydrant was made of wood and installed in 1808 at the corner of William and Liberty Streets. By 1817, the first regular iron hydrants were being installed throughout the city. Fire hydrants have not changed much since New Yorker Birdsill Holly, Jr. patented his “improved fire hydrant” design in 1869.

Even though the materials used to create hydrants have improved and some design refinements have been made, the two types of pressurized fire hydrants - wet-barrel and dry-barrel - have remained relatively unchanged since the mid-1800s. Wet-barrel hydrants are always directly connected to the pressurized water source, and are found in warm climates throughout the world. Dry-barrel hydrants are separated from the pressurized water source by having the main valve located in the lower section of the hydrant underground, and remain dry until the main valve is opened. They are usually found in areas where winter temperatures fall below 32º F (0º C), including those found in New York City. The most common of which is the A. P. Smith’s 1902 “O’Brien” hydrant, followed by the Dressler’s “Traffic 500” hydrant. Modern hydrants are even designed to break away in case a car hits them!

Until fires become a thing of the past, fire hydrants are here to stay. Fire hydrants have evolved from their humble beginnings as simple fire plugs to a network of strategically placed hydrants that effectively and efficiently keep New York City and its residents safe.

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