Hydrogenous species play a key role in radiation induced charge buildup in metal oxide semiconductor field effect transistors (MOSFETs). The amount of hydrogen present in ambient gases used during device fabrication can be correlated to the concentration of radiation-induced interface traps post processing. The effects of water on defect formation in MOSFETs before and after radiation exposure have been studied. Greatly enhanced post-irradiation defect generation was observed in the gate oxides of p-channel MOS transistors that were exposed to water. Low frequency (1/f) noise measurements also showed enhanced noise power spectral densities in the p-channel transistors consistent with the enhanced post-irradiation increase in defect density. Phosphorus and boron dopant atoms are present in the field oxides of the n-channel and p-channel transistors because of source and drain implant steps. This can lead to enhanced water-induced defect formation in the gate oxides of p-channel transistors compared to n-channel transistors before and after irradiation. These results are significant for the performance of MOS technologies in non-hermetic environments.