wrote
Robert Gammon wrote

Not Canada, Australia has the spec

http://www.dux.com.au/tech_domestictemp.htm

I thought that was because of the peculiarity of bacteria in the wooden
dams that hold the water supply for the area around Sydney, NSW.

No such animal.

Certainly not a worldwide norm.

Precisely the same type of dams are used around Sydney
as are use virtually everywhere else in the first world.