•PFAS serum concentrations for an exposed community are presented.•PFOS, PFOA, and PFHxS serum concentrations were higher than general US population.•A coordinated national response is needed to better address PFAS contamination. Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in manufacturing that resist environmental degradation, can leach into drinking water, and bioaccumulate in tissues. Some studies have shown associations with negative health outcomes. In May 2014, a New Hampshire public drinking water supply was found to be contaminated with PFAS from a former U.S. Air Force base. We established a serum testing program to assess PFAS exposure in the affected community. Serum samples and demographic and exposure information were collected from consenting eligible participants. Samples were tested for PFAS at three analytical laboratories. Geometric means and 95% confidence intervals were calculated and analyzed by age and exposure variables. A total of 1578 individuals provided samples for PFAS testing; >94% were found to have perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) detectable in serum. Geometric mean serum concentrations of PFOS, PFOA, and PFHxS were 8.6 μg/L (95% CI:8.3–8.9), 3.1 μg/L (95% CI: 3.0–3.2), and 4.1 μg/L (95% CI: 3.9–4.3), respectively, which were statistically higher than the general U.S. population. Significant associations were observed between PFAS serum concentrations and age, time spent in the affected community, childcare attendance, and water consumption. PFOS, PFOA, and PFHxS were found in significantly higher levels in the affected population, consistent with PFAS drinking water contamination. Given increased recognition of PFAS contamination in the U.S, a coordinated national response is needed to improve access to biomonitoring and understand health impacts.