The colored cap on a US fire hydrant can tell firefighters how much water it can deliver: Blue means 1,500+ gallons a minute, while red warns of under 500

Fire hydrants are marked with color codes that indicate the water flow rates they can provide. A light blue cap means a hydrant can flow more than 1,500 gallons per minute. The National Fire Protection Association has established a four-color system for hydrants to help firefighters respond efficiently. Local fire departments often adopt this color scheme, but compliance may vary across different regions.