Funny, I thought that a fire hydrant was actually supposed to be used to provide water to fire fighters so they could . . . . . . well, put out fires. Of course, the name "fire hydrant" sounds a lot snazzier than "system flusher outer thingy".
Sarcasm aside, this is bureaucratic BS. The city is apparently siphoning the funds off for maintaining the fire hydrants and using the money elsewhere. Terrorism just makes a good cover story. Were I the homeowner and/or the HOA, the city would be facing a lawsuit over this. If they are going to use terrorism and safety as a cover story, it works both ways. Benjamin Franklin developed the Fire Department system as a safety issue for the public and to try to prevent fires from devastating neighborhoods.
Uh, read the story again. It sounds like (1) it was not in a city but a somewhat rural area and (2) the supplier is a private utility, not the city.