Okay, lets' assume you want to privatize is, with some solution for "what about people with no money" (whether that's universal healthcare and fantastic welfare or something else is beside the point) 
There is no conceivable way to have two competing companies building dams, reservoirs and supply lines, competing companies building sewage systems (including easements to go under people's private property).
So - invariably you're going to have just one company doing it. Even if you split the task among companies - they aren't competing. The sewage company isn't in competition with the damn company. It's going to be a monopoly. So the company has no incentive to be any more efficient, cheap or provide better service than government was. Even the claimed advantages of the private sector don't happen - there is nothing to make them happen.
Furthermore what used to be operating procedures must now become laws and regulations. TBC.