Sophisticated but low-tech power grid attack baffles authorities

I've always wondered how vulnerable infrastructure is to physical attack. Kinda scary what a group of people could do with coordinated attack on multiple substations at the same time. A month to fix everything? Yikes!

I wonder how vulnerable a water tower would be to a similar attack. Obviously, water towers are typically around more populated areas and I have to imagine that they're made of some pretty thick gauge steel, but armor piercing ammo isn't that hard to acquire.