From the blog:
"This new tank, along with a similar recently installed tank, is fully enclosed and contains ‘food grade' internal bladders which hold the water. The new tank replaces the previous underground storage tank known as ‘the Pit' (which was also filled with town mains water but was not fully enclosed), which is no longer in use.
The two above ground tanks have been filled with water sourced from Central Highlands Water who conducts routine water testing prior to being released into pipes/taps for general water use."
Accompanying Mick Bourke's update is a diagram explaining the water system at Fiskville. See below.