Only firefighters are permitted to open a fire hydrant. School classes can visit a New York City Firehouse for a demonstration of equipment and to meet the firefighters. Call your local fire department to make an appointment. Hydrants are for fire fighting, not for fun. Each time a hydrant is opened illegally, a thousand gallons of water are wasted each minute.
Children risk serious injury from the powerful flow.
There is also a severe loss of water pressure, which means that if there is a fire, someone might be injured or die. So if you need to cool off, try the beach or the nearest pool, or get an approved spray cap for a neighborhood hydrant from your local fire house.