[snopercod]

I didn't know about the low water pressure. Did not each tower have a storage tank up top?

Who would have ever considered that both towers would need water at the same time?

[DuncanWaring]

Even if each tower had a storage tank up top, it would have been sized for what was believed (when designed) to have been a worst-case fire.

The fires they actually encountered were, obviously, far beyond that. Furthermore, it was expected that the water would have been spraying out through the sprinkler nozzles; instead, it was most likely gushing torrentially out through mains that had been "rent asunder" by the impact.