 The census area that incorporates Waterfall Gully has a larger proportion of those in both the younger (0–17) and older (60+) age ranges than in the City of Burnside as a whole, and there have been no "numerically significant" changes in the age distribution between the 2001 and 2006 censuses.Similarly, family numbers are also stable, with almost no change between 2001 and 2006.The 2016 Australian census which was conducted in August 2016 reports that Waterfall Gully had a population of 145 people.