In newer buildings the water may not have been in the pipes long enough for the crap to form in it. Also, in more recent years, sprinkler systems are actually more likely to have been tested at regular intervals, which would exchange the water in the pipe (at least some of the pipe) every so often if tested from a properly located inspector's test valve (at the farthest point on the system from where water comes into the building).

I don't think a fire in an office would be a good idea. I was just suggesting alternatives like a fire outside the building.



ROFL, that's awesome.

I have never heard of any problems caused by the gunk in the lines that would affect whether the sprinkler system would be able to flow water. Those systems are at a very high pressure and will blow whatever is in the line out, no problem.

The only issue I know of is sometimes shutoff valves won't fully close after years of buildup, and every now and then a waterflow switch won't reset to normal operation after water stops flowing in the system (i.e. - during a fire or a system test). The water still flows fine, it just causes issues with the fire alarm system detecting the operational status of the sprinkler system.