What Do Fire Hydrant Colors Mean?

We're all familiar with bright red fire hydrants, the color of which has become synonymous with them, fire trucks, and the hats many fire chiefs and firefighters wear. You may even know what it means when a fire truck honks three times. 

But despite the association between red and firefighters, red isn't the only color hydrants can be. There's a whole range of colors you'll see on hydrants in the United States. Their caps and barrels can even be different colors from one another.

As with police cars using flashing yellow lights or the different colors used for road reflectors, these colors aren't just for show. They quickly signal information to firefighters about the hydrant, particularly the gallons per minute it's capable of. This indicates how much water will come from the fire hydrant and how quickly, as well as the general water pressure — crucial for firefighters to know when there's a fire.

Fire hydrant caps generally have one of four colors, representing the fire hydrant's class based on its gallons per minute. The National Fire Protection Association suggests that red caps should indicate Class C, which means the available flow is under 500 gallons. Orange caps should be for Class B, with between 500 and 999 gallons; green for Class A, with 1,000 to 1.499; and blue for Class AA, with more than 1,500 gallons per minute.

While these colors are relatively standardized, it's important for firefighters to make sure they represent these classes in the city or county they're working in. The Fire Protection Association's standards are only a set of guidelines and recommendations, not a law, so some places use another color system. But standardizing the colors can help when firefighters from a neighboring community are called in to deal with a major conflagration.

Colors on fire hydrant bodies, or barrels, are less clear-cut than the cap colors — but they also generally convey less information. There are some recommendations in place, however. The National Fire Protection Association recommends that all public-system fire hydrant barrels be painted a reflective yellow, private-system hydrants be red, and reclaimed-water systems' hydrants be painted violet. (Reclaimed-water systems use treated wastewater that isn't safe for human consumption, but is fine for firefighting.) Finally, the federal Occupational Safety and Health Administration recommends that out-of-service fire hydrants be painted black.

But all of these are only recommendations, and you'll see fire hydrants with bodies and caps in other colors. For example, in Los Lunas County, New Mexico, fire hydrant bodies are painted a reflective silver to make them easier to see, especially at night. In Nashville, some fire hydrants have a white barrel, which signifies a hydrant at the end of a system line, while a red barrel is used for other public hydrants — and the caps are black, green or orange, for Class C, B, or A respectively. And in still other locations, the fire hydrant body is painted the same color as the cap.