We here report on a study that examines the performance of a water based personal condensation particle counter (CPC) PUFP C100 (Enmont, LLC) when sampling a variety of different test aerosols. Three additional CPCs were included in the study, namely, the general purpose water based CPC model 3787 (TSI) as well as the more than 20 year old CPC model 3022 (TSI) and ultrafine CPC model 3025A (TSI), both based on butanol. The responses of these CPCs were compared to a reference ultrafine CPC model 3776 (TSI). Test aerosols included hydrophilic NaCl, moderately hydrophobic carbon and highly hydrophobic DEHS aerosols of various sizes and concentrations. The CPC PUFP C100 measured according to its specifications with high precision and accuracy as long as the particles were not highly hydrophobic, but failed to adequately measure the concentrations of highly hydrophobic DEHS aerosols. Its detection efficiency for very small particles, e.g., 5.4 nm, was decreased, which was expected based on its particle size detection limit. The TSI water CPC model 3787 showed a similar behavior for all aerosols, except that this CPC was able to accurately measure the concentration of 5.4 nm NaCl particles. The concentrations measured with the two old and unserviced butanol CPCs were highly correlated with the concentrations delivered by the reference CPC. Nevertheless, the concentrations measured with both old CPCs were clearly below the reference concentrations.