The aqueduct

Carrying drinking water through open channels has a long history and the Romans of course had some great aqueducts, with their use of bridges being particularly notable.   Growing up, I was aware of the existence of some aqueducts forming part Melbourne's water supply system.     I now read that there was the O'Shannassy aqueduct in the Yarra Valley which is no longer used (see here and here).    

There was also the Maroondah Aqueduct, which I read was built in 1886–1881 to supply  water to the Preston Reservoir.  This, too, has been closed in a number of places and there's a walking/biking trail along part of it. There's also a disused section of this aqueduct that intersects the Yarra Glen to Christmas Hills Road.

Although in this era of steel pipes, we tend to think of this technology as a bit "yesterday", in fact there are still sections of the Maroondah Aqueduct in use today.   There's a reference here to over 30 kms of it still being in use (but my limited googling hasn't confirmed this distance).

Why am I saying this?  It's because, immediately behind Balgownie Estate (where we stayed recently), just a little further up the hill, a section of aqueduct is alive and well!    It's fenced off, and there are emphatic "do not enter" signs, but it most definitely is still is use.

Here's a link showing the location of the section of the aqueduct where it passes behind Balgownie Estate (the big while blobs are the accommodation blocks).