In the United States, the AWWA and the NFPA recommend painting the top of fire hydrants different colors depending on the available flow of water.  I did not look up what those acronyms stand for, but I trust them.  Anyway, from strongest water flow to weakest, the colors go from light blue, green, orange, and red.  If you live in a neighborhood with a fire hydrant that has a light blue bonnet, congrats! You are a badass!