An eWMD shuts down water supply: people have to resort to bottled water and, in a worst case scenario, boil rain water; for a few weeks
First, boiling rain water for a few weeks is a laughable concept when discussing survival solutions. To prove my point just go ahead and turn off your water right now put your plan into action.
Second, I'm sure many water supply systems are connected to the internet, but only for remote monitoring purposes. They're probably at greater risk of dying from BSOD than a botnet. Besides, even if the computers were do go down, industrial motors are quite easy to wire up directly to a power source and the required components are most likely already on site from before the facility was computerized.
What's the capital of the middle-east again?
Iraq, that's where the terrorists who bombed the World Trade Center are from.
A committee takes root and grows, it flowers, wilts and dies, scattering the seed from which other committees will bloom. -- Parkinson