Wastewater contains a wealth of information about the population who contribute to it including biological and chemical markers of human activity and exposures. F2-isoprostanes have been proposed as oxidative stress biomarkers that can be measured in wastewater to provide a measure of oxidative stress at the population level. While an association between tobacco use and their level in wastewater has been demonstrated, an in-sewer stability assessment has not been conducted to support their use as oxidative stress biomarkers for wastewater-based epidemiology studies. In this study we investigated the stability of 8-iso-prostaglandin F2α (PGF2α), its metabolite dinor-11β-Prostaglandin F2α (dnPGF2α) and Prostaglandin E2 (PGE2) (representative of other classes of prostaglandins) in laboratory-scale sewer reactors simulating real sewers. PGF2α, dnPGF2α and PGE2 were all found to be sufficiently stable under typical sewer conditions therefore satisfying the stability requirement of wastewater-based epidemiology population health biomarkers.