How, if at all, would interdependencies between the water sector and other CI/KR sectors affect your view?

Considering the familiar axiom, “the solution to pollution is dilution,” do you believe that the water sector is highly vulnerable? If so, which specific elements, systems, facilities or processes seem most vulnerable? Or, do you believe the threat to our water systems or supplies is exaggerated, and that this CI/KR sector is not really all that vulnerable, or that terrorists would not be attracted to those targets because it would be too difficult to create mass casualties or actual terror through attacking the water system due to the sheer volume of water diluting any potential contaminants? What about wastewater systems? How, if at all, would interdependencies between the water sector and other CI/KR sectors affect your view? Support your assertions and conclusions with logical arguments and evidence from research in authoritative sources.