This project aims to analyse the nicotine metabolites and tobacco-specific alkaloids excreted from the human body in the wastewater samples collected by the National Wastewater Drug Monitoring Program over the period from June 2021 to June 2023 across Australia. The results will provide the total consumption of nicotine containing products, as well as the tobacco use estimation data (with the minimum influence of e-cigarettes use) based on wastewater analysis. In addition, this project will partly investigate the pattern of e-cigarette consumption by analysing the ratio of tobacco alkaloids to nicotine metabolites in wastewater. Furthermore, by combining with the cigarette sales data provided by the Australian Taxation Office, this project enables us to identify the proportion of illicit tobacco use in Australia.