Per- and polyfluoralkyl substances (PFASs) are ubiquitous contaminants in the environment and classified as chemicals of concern due to their persistence, toxicity and wide-spread historic use. Wastewater treatment plant (WWTP) influent and discharge streams are important for understanding the cycling of PFAS in the environment. Passive sampling has emerged as a complementary method for time-integrated approach to monitoring in wastewater. This is the first study to develop, calibrate and validate a microporous polyethylene tube (MPT) passive sampler for quantitative the estimation of PFAS in wastewater. This study aims to calibrate MPTs in situ at one WWTP to determine sampling rates and compare with sampling rates across multiple WWTP sites. To achieve the objectives, samplers deployed in the field are calibrated by comparing analyte accumulation with time‐averaged concentrations in water obtained from high‐frequency grab sampling. Two MPT configurations were investigated in this study; Strata-X; and Strata-X containing agarose gel to assess the effects of increasing the diffusion pathway. Anionic species represent dominant PFAS in aquatic environments due to water solubility and are the most widely studies, therefore were selected for this study. Results of this study will provide sampling rates for deployment in wastewater and insights into the factors that may influence chemical uptake behaviour, for example flow, temperature, pH, DOM and presence of microbes.