Daniel walks past a green fire hydrant and wonders why it isn't red.

The colors are not decoration. They can be information.

Fire departments and water systems can use color to tell firefighters important things about a hydrant at a glance. Under a system recommended by the National Fire Protection Association, the color on the top and caps of a hydrant can indicate its rated flow capacity -- how many gallons per minute it can deliver. Light blue for the highest flow. Green for strong. Orange for moderate. Red for the lowest. A firefighter arriving at a fire can read that at a glance and know what water supply they are working with.

The body of the hydrant can carry different information -- helping distinguish between public and private hydrants. And a violet or purple marking is used in many systems to identify non-potable wate ...