[syrac818]

Now I understand this is a fairly broad question, and I'm not taking into account the petroleum needed for maintenance vehicles, piping, drilling, etc...

But does anybody have a rough idea? I'm wondering, because I've been in some pretty rough countries, and a good amount actual had some sort of running water (it wasn't drinkable..but whatever). Just curious.

[Heineken]

In the U.S. at least, I think the water-pumping stations use mostly electricity.

[cynthia]

Read, High Noon for Natural Gas: The New Energy Crisis, By Julian Darley
Natural Gas is used to transmit water to too many places that people rely upon.

[OverLord]

The following article doesn't go very deep into technical issues, but hints as how dependant the water supply system is on oil and natural gas.

http://www.fromthewilderness.com/free/w ... es.shtml#2

"Back in the USA: picture the state of mind of ornery citizens if four in ten people had really bad or insufficient water. It will be over 9 in 10 come petrocollapse. This is because of the extreme dependence on massively complex and centralized water supply systems that are run with mainly energy or materials from oil and natural gas. "

[Barbara]

I've read somewhere that my city (Rome) still rely about 70% on ancient roman aqueducts working with gravity. But couldn't find any deep references on municipal web site or water department web site. I mean, surely we still use much of roman aqueducts, but don't know how much it's independent from the grid.
Our major, anyway, often says our water wouldn't need purification because it comes 100% drinkable and pure from the mountains. Of course, they purify it because it's the law.