In films we often see New York fire hydrants spouting water in which local children enjoy themselves. Do the locals turn these on themselves, or is there a reason why the authorities do it?

The Fire Departments across the country do this on a regular basic: Reason, to clean any trash out of the lines so their sprayers do not get stopped or clogged....

I am unaware of any fire department doing what Fritzz suggested, even though it seems to make some sense. I have always thought that the hydrants were opened illegally by residents of larger cities to cool off in the summer. The links below indicate that.

CITY OFFERS SAFE ALTERNATIVE TO ILLEGAL OPENING OF FIRE HYDRANTS - With more hot weather in the forecast, the City of Detroit reminds everyone that it is illegal for anyone other than a Detroit firefighter or other official City worker to turn on a fire hydrant. Turning on a fire hydrant is a misdemeanor punishable by a fine of up to $500 or up to 90 days in jail. - The Official Web Site of the City of Detroit
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On a hot summer day, a cold spray of water from a fire hydrant may seem awfully appealing. It's actually awfully dangerous for you, your neighbors, and especially for children. Water shoots from hydrants at very high pressure and can mean accidents and injuries.

Additionally, opening fire hydrants is illegal. As an example, the City of Oakland's Ordinance No. 12414 makes tampering with a fire hydrant punishable by up to six months in jail and/or a $1,000 fine.

Open hydrants also:
Lower pressure in nearby homes and makes it harder to fight fires.
Waste water which can mean water shortages, especially during droughts.
Can damage the water system and increase water bills.
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EBMUD is working hard to convince people to stop opening hydrants. We are educating school children about the problems of opened hydrants and are installing special locking caps. We are also working with fire departments to develop procedures for dealing with massive hydrant openings.
The East Bay Municipal Utility District (EBMUD) supplies water and provides wastewater treatment for parts of Alameda and Contra Costa counties on the eastern side of San Francisco Bay in northern California. EBMUD is a publicly owned utility formed under the Municipal Utility District Act passed by the California Legislature in 1921. - ebmud.com
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"
CITY’S ILLEGAL HYDRANT OPENINGS ARE DOWN

Department of Public Works George L. Winfield has announced that the number of illegally opened fire hydrants in Baltimore City has dramatically declined this year.

As part of a preventative program initiated by the agency, over 1800 fire hydrant locks have been installed throughout the City in critical areas such as near hospitals and hi-rise apartment buildings. These can only be opened with a special wrench possessed by firefighters and Public Works employees.

At this time last year, there had been over 1,000 hydrant openings. This year, that number has declined to 350.

Open hydrants reduce water pressure, handicap firefighters and affect high rises and hospitals. Citizens who spot an open hydrant are urged to contact the department immediately by calling (410) 396-5352." Dept. of Public Works, City of Baltimore
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"THE CHICAGO HEAT WAVE

"The city set new records for energy use, which then led to the failure of some power grids-at one point, 49,000 households had no electricity. Many Chicagoans swarmed the city's beaches, but others took to the fire hydrants. More than 3,000 hydrants around Chicago were opened, causing some neighborhoods to lose water pressure on top of losing electricity. When emergency crews came to seal the hydrants, some people threw bricks and rocks to keep them away. . ." - Urban News

The locals do it. New York City offers “spray caps” for fire hydrants.

"Spray caps," which can be obtained from your local fire station, can be installed on any fire hydrant to produce a circular spray of cool water, reducing output to a safe level while still providing relief from the heat. To obtain a spray cap, simply visit your local fire station. You must be 18 or older to obtain a spray cap.

I've never lived in a town or city that DIDN'T do it.... Here in Naples, it is done once a year at each indivual hydrans....

Where I live now (Suffolk County, New York) the Suffolk County Water Authority, (a public benefit corporation) not the fire department does open fire hydrants on a regular basis to clear the lines out and remove debris. We are told to call the water company if we notice “rust colored water” and their “fix” is to come by and open the hydrant for a specific amount of time to clear out the iron deposits. I did notice them doing it last week in my neighborhood. The flood on my block was proof of that! Thankfully we have great drainage here. (Being on a pile of sand and rocks sure helps) It seems that they do it several times a year.


Why does my water look…

It is illegal for an individual to turn on the fire hydrant without official approval. I believe this applies to every state. Here in Detroit you can call the city and they will send someone to open a hydrant and water down the street. I remember a few years ago a child was hit by a car while playing in the water of an open hydrant. The man who opened the fire hydrant was charged and was given jail time and a fine. The caps on the fire hydrants are not easy to open. Many times people will force them open with sledgehammers or they will tie a rope around their car and try to pull the hydrant up from the ground. Every year there are stories about firefighters going to put out a fire only to find the hydrants don't work.

City officials open the hydrants to make sure they are operating properly. I know they check the water pressure and the condition of the caps. There is a complete checklist they must follow.

What's a fire hydrant? It used to mystify us, as youngsters, to see American films where there were things by the road that sent great jets of water out when hit by vehicles in chases or were used as fountains in Summer.We were really envious that American kids had street fountains even in the poorest areas. Aren't you lucky ! Our equivalent devices are under manhole covers in the road, so are not accessible to any but the Fire Brigade.

Fred. I have to ask how your fire house dogs find the hydrant if yours are under the road.

DG
I've always wondered that despite being a UK resident
The only clue is a yellow sign of about 9 inch square with a black "H" and some number regarding the distance of the cover in inches? and how deep the pipe is(also in inches)
Not a very good method I think the system came in in the late 1940's?!
I think It's overdue for "improvement"?
The previous water supply was marked by yard high letters"E.W.S" painted(in white or Yellow) on a wall denoting there was a water tank or mains supply very close (this was as far as I know only for the period of World War 2) Many Examples still can be seen Clearly
www.bbc.co.uk/cumbria/features/askaway/buildings/ews.shtml

DG The Fire Brigade keeps only a fire station cat. British dogs have British pillar boxes to use; the big cast iron scarlet things about five feet high and three feet or more wide that are deemed just big enough to take letters. They can only be that big for the dogs; for all their bulk, they contain just tiny wire mail baskets occupying a very small part of the interior. They are painted red so that the dogs can see them easily from a distance.Chances are the dogs can't see red but, no matter, the smell is surely enough !

There was an "Emergency Water Supply" at the top of our street. It was built on the ruins of a bombed out row of shops, (bombed in the May blitz on Liverpool) and was about 90 feet square. The wall around it was about 5 feet high (It seemed a lot higher to us kids) and the water in came up ground level. From memory it was about six feet deep.

Dorian, maybe it's an Illinois thing, I'm with you on this. I wasn't aware of it either. I've never seen the Fire Dept. flushing the hydrants. I do see city crew cleaning the debris/trash from the drains, though.