When a summer heat wave engulfs New York City, people seek the soothing embrace of water in whatever way they can: they swarm the neighborhood swimming pool; they visit the beach at Coney Island; they take multiple showers. People also tap into the city's water supply through some of its most vulnerable access points: fire hydrants. Wrenching open fire hydrants to frolic in the resulting spray is a summertime custom in cities and suburbs nationwide—often with unconsidered consequences.

An opened fire hydrant in New York gushes 1,000 gallons of water a minute, draining the same reservoirs that supply kitchens, bathrooms, and—of course—fire hoses. "It's illegal for private citizens to open fire hydrants on their own," says Farrell Sklerov, a spokesman for the Department of Environmental Protection (DEP). "What people are supposed to do is ask for a spray cap from their local firehouse."

Free of charge, NYC firemen will install or lend out perforated caps that cut down a hydrant's gushing to 25 gallons per minute, while still providing constant jets of water for the hot and bothered. The caps help prevent water pressure from dropping dramatically in nearby homes and buildings.

"One open hydrant on a block will probably not impact water pressure that much," Sklerov explains, "but a significant amount of open fire hydrants impacts water pressure to the point that we get tons of 311 complains." During the July 5 to 7 heat wave, the DEP received so many 311 hotline complaints about low water pressure that they launched a fleet of teams to shut down more than 1400 opened fire hydrants each day. The city maintains 107,000 fire hydrants throughout the five boroughs.

Sometimes, illegally opened fire hydrants have more dire consequences. The force with which the hydrants spout can catch people off guard, knocking them into harm's way. In June 1994 a three-year-old girl playing in front of an open fire hydrant in Manhattan died after the gushing water flung her into the path of an oncoming sanitation truck, The New York Times reported.

Such cases are fortunately rare. The primary objection to opening fire hydrants without spray caps is the sheer waste of resources. In the case of New York, opening fire hydrants illegally doesn't waste much energy, because water travels to the city almost solely by gravity and New York is one of only a handful of major cities that don't rely on expensive artificial filtration systems, since the majority of the city's water comes from naturally filtered and protected sources. For most cities and suburbs, however, uncapped fire hydrants waste precious water and energy—especially during heat waves and droughts. 

This summer's June was the driest June on record for New York City since June 1999 and, as of July 16, the reservoirs were at 86.4 percent of their capacity, the DEP told the Times. Usually, reservoirs are at 93.4 percent capacity in mid-July.

"We understand people want to stay cool," Sklerov says, "but there's an appropriate way to do it: go to local firehouse and they'll hook up a spray cap for you."

Technology might facilitate water conservation as well. Some companies are working on a new generation of intelligent fire hydrants that perpetually monitor water usage and sound the alarm if someone tries to open them without permission. SmartHydrant, currently in predevelopment, will wirelessly transmit data about leakages and tampering. And the Mi.Hydrant by Mueller Systems, recently introduced at the American Waterworks Association trade show, can similarly store and send information about leaks, backflow and other maintenance issues.

But Sklerov says the DEP is not currently looking to deploy smart hydrants, because the current methods of identifying and resolving illegally opened hydrants work just fine.

Image of fire hydrant courtesy of Wikimedia Commons