Stable isotope analysis of human tissues has become a valuable tool for mapping human geolocation. This study adds to the existing knowledge of the relationship between oxygen stable isotopes in human enamel (δ 18Oenam) and drinking water (δ 18Odw) by presenting δ 18Oenam values in clinic-extracted human dental enamel with known provenance. The results from this study indicate that the theoretical isotopic relationship between 18Oenam and 18Odw is valid although weak at the city and country-level. However, differences of up to 15‰ were observed between predicted δ 18Odw values using existing models and observed values, highlighting the complexity of using enamel-to-water conversion equations. A city-specific range of δ 18Oenam values is now understood for Metro Vancouver [δ 18Ocarbonate = − 9.7‰ to − 7.2‰] and presents the possibility of both including within the city of Vancouver and excluding individuals, utilizing stable oxygen analysis as an exclusionary tool. Overall, this study’s results support the development of tissue-specific d 18Oenam geographical reference maps for human geolocation.