Street revelers leap through an open hydrant at the corner of North Third Street and Bedford Avenue in Williamsburg, Brooklyn. (Photo by Rolando Pujol)

On a steamy Saturday in late July, the fire hydrants along Williamsburg’s Bedford Avenue were cracked and showering arcs of cool water over clusters of shrieking pedestrians and the street, which was closed to cars that day for a festival.

These were not spouting geysers – the telltale sign of an illegally popped hydrant. The hydrants were fitted with spray caps, perforated lids mounted by the fire department, which release the water in a controlled stream like a sprinkler or showerhead.

So how exactly do you get the fire department’s consent to open a hydrant? It’s easier than you may think.

“Someone has to call the neighborhood firehouse and make a request for one of the trucks to open a certain hydrant,” said Firefighter Alex Bartley. “When we do it, it’s because of the heat, for the kids and the neighborhood – whoever needs to cool off.”

The FDNY conducts regular water pressure tests to determine whether it’s safe to open the hydrants, Bartley said. Low pressure from an open hydrant could impede the department’s ability to fight fires.

Spray caps have been in use at least 20 years as a measure to save water. When a hydrant is opened illegally, it spews out about one thousand gallons of water per minute which adds up to one million gallons over 24-hours, according to the Department of Environmental Protection.

“One hour of an open hydrant would be enough to fill an Olympic-sized swimming pool,” said DEP spokesperson Mercedes Padilla. The caps slow that stream to 25 gallons per minute.