[sam_paine]

If one does the calcs, it is very difficult to conduct a massive poisoning by water supplies unless it is done directly at local treatment facilities.

That's not completely true. Water distribution systems are not one-way. If you really do the math, it would seem to me that terrorists could inject poison into a water main from any house/commercial building they decide to set up in.

They would need a pump that could pump X GPM of poison at greater pressure than is presented at their tap, say like 60 psi, or maybe a coupla horsepower. depending on where in the system they pick, they could get huge amounts of crud into the system without any accurate way of detecting the source. Pump stations require huge pumps to fill massive GPM at the same pressure...whereas you need less pressure to get a small flow backdriven through a 2" feed from the street.

You don't need to "back a truck up" to a resevoir out in the open!!!

So we should pull the records of Ozarka and Culligan and see if any of their customers drink a suspicious amount of bottled water in a small building.....

[Texasforever]

The fact is that it does not require massive casualties to be effective. One instance and every water source in the country would come under suspicion and people being what they are would be afraid to use anything but bottled water for some time. Look at the reaction to 5 anthrax deaths.