Exposure to enteric pathogens in the environment poses a serious risk for infection and disease. The accurate detection and quantification of enteric pathogens in environmental samples is critical for understanding pathogen transport and fate and developing risk assessment models. In this study, we successfully applied TaqMan real-time PCR assays to quantitatively detect five human-specific pathogens (Shigella/EIEC , Salmonella Typhi , Vibrio cholera , Norovirus, and Giardia) in samples from open drains, canals, floodwater, septic tanks, and anaerobic baffled reactors (ABR) collected in Mirpur, Dhaka, Bangladesh from April to October 2019. Overall, the grab and sediment samples showed low inhibition but the ultrafiltration samples collected from open drain had significantly higher (P = 0.0049) degree of PCR inhibition (median Ct = 31.06) compared to the extraction controls (Ct = 28.54). We developed a two-step method to adjust underestimation of pathogen quantities due to PCR inhibition and non-optimum PCR efficiency. Compared to other sample types, ultrafiltration samples demonstrated a wide range of concentration increase (1.0%–182.5%) by pathogens after adjusting for PCR inhibition and non-optimum efficiencies. These quantitative qPCR assays are successful in quantifying multiple enteric pathogens in environmental samples, and the adjustment method would be useful for correcting underestimates of pathogen quantities due to partial PCR inhibition and non-optimum efficiency. • 154 environmental samples from open drains, canals, floodwater, septic tanks, and anaerobic baffled reactors (ABR) were collected. • Five quantitative TaqMan real-time PCR assays were used to detect Shigella/EIEC , Salmonella Typhi , Vibrio cholera , Norovirus , and Giardia. • Spiking the samples with MS2 and PhHV indicated that ultrafiltration samples had significantly higher degree of PCR inhibition. • A method was developed to adjust the underestimation of pathogen quantification due to PCR inhibition and non-optimum PCR efficiency. • The correction method resulted in an approximately two-fold increased Giardia concentration and a significant increase of other pathogens. [ABSTRACT FROM AUTHOR]