Every few decades the Hawkesbury River, a muddy, meandering waterway that forms a natural border from Sydney’s west to its north, rises above its steep banks and wreaks chaos.

Windsor residents still talk about the great flood of 1867, when 12 members of the Eather family – two sisters-in-law and 10 of their children – were washed away from the roof of their house, screaming, and never seen alive again.