In the case of water, why do our guys think they would choose a conventional poison? Would they bring in truckloads of conventional poison? Not likely.
Dirty bombs? How about "Dirty water" -- with the dead body of the messenger/martyr glowing by the reservoir? Or glowing by an aquifer break point?
There is mistake here, my son is Class A adv water trt opr for small town, and there is 2 million gallons of water at plant at one time, with guys sitting on 250,000 lbs chlorine gas used for treatment...this is a viable threat. In fact, they have been on alert for some time...last year especially, so much so that police often come and visit for lengthy timeperiods. Our water supplies are out in open and some cities/towns do not have enough funds to have extra operators onboard. It is not right, and I have been mad at our local city for some time. Don't discard that warning.
You've got it, it does not take as much as one would think to made a whole town sick.
The act of putting 250,000 gallons into a 2 Million gallon res are extremely remote!
It would take over a full day to pump that much chlorine for one thing, and the other would be the dilution effect.
It would not kill everyone who drank it, just make us buy bottled water for no more than 2 weeks.