18 December 2025
People living in socially disadvantaged and regional areas of Australia are consuming significantly more cannabis than their counterparts in wealthier metropolitan towns and cities, a new study has found.
Published in the journal Addiction, the study involving researchers from The University of Queensland (UQ) and University of South Australia (UniSA), is the first to combine large-scale wastewater analysis with national survey data to track cannabis use trends across Australia between 2018 and 2025.
By analysing wastewater samples from treatment plants serving more than 13 million Australians, alongside data from the National Drug Strategy Household Survey, researchers found that cannabis use has steadily risen across all communities.
The study shows that the most disadvantaged communities recorded more than double the consumption rates of the wealthiest areas over the seven-year period.
Lead researcher Dr Rory Verhagen, a Research Fellow at UQ’s Queensland Alliance for Environmental Health Sciences, says that outer regional and remote areas also consumed more than two and a half times the amount of cannabis compared with major cities.
“That gap has persisted over time, providing a rare, objective insight into population-level drug use and highlighting the need for targeted health responses,” says Dr Verhagen.
“The patterns were remarkably consistent across both wastewater data and self-reported survey responses, strengthening confidence in our findings.”
Co-author UniSA Associate Professor Cobus Gerber says that cannabis consumption increased annually across all socio-economic groups between 2018 and 2025, with growth rates ranging from around three to five per cent per year.
“Combining wastewater monitoring with traditional surveys provides a more complete picture of drug use in the community,” says Assoc Prof Gerber.
“Surveys are invaluable and provide information about individual preferences, but they can miss heavy or marginalised users and are only conducted every few years. While wastewater analysis captures the entire population, it assures anonymity and is conducted up to bimonthly to detect changes much more quickly.
“This dual approach allows us to see both long-term trends and emerging shifts in use, which is critical for timely public health planning.”
The findings come amid ongoing debate about cannabis regulation in Australia. While recreational cannabis remains illegal nationally, social attitudes are changing, and medicinal use has increased in recent years.
The researchers say the results underline the importance of addressing the social and structural factors that influence drug use.
“Higher consumption in disadvantaged and remote communities likely reflects a complex mix of attributes such as access to services, economic conditions and social norms,” Dr Verhagen says.
“Prevention, education and harm-reduction strategies need to be tailored to the communities most affected.”
‘Cannabis consumption in Australia 2018-2025: Socio-economic and regional trends from wastewater and survey data’ is published in Addiction. DOI: 10.1111/add.70277. The study was funded by the Australian Criminal Intelligence Commission (ACIC).
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Media contact: Candy Gibson M: +61 434 605 142 E: candy.gibson@unisa.edu.au
Researcher contact: Professor Cobus Gerber M: +61 423 496 066 E: cobus.gerber@unisa.edu.au Dr Rory Verhagen E: rory.verhagen@uq.edu.au
