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Young stars emit strong flares of X-ray radiation that penetrate the surfacelayers of their associated protoplanetary disks. It is still an open questionas to whether flares create significant changes in disk chemical composition.We present models of the time-evolving chemistry of gas-phase water duringX-ray flaring events. The chemistry is modeled at point locations in the diskbetween 1 and 50 au at vertical heights ranging from the mid-plane to thesurface. We find that strong, rare flares, i.e., those that increase theunattenuated X-ray ionization rate by a factor of 100 every few years, cantemporarily increase the gas-phase water abundance relative to H can by morethan a factor of $\sim3-5$ along the disk surface (Z/R $\ge$ 0.3). We reportthat a "typical" flare, i.e., those that increase the unattenuated X-rayionization rate by a factor of a few every few weeks, will not lead tosignificant, observable changes. Dissociative recombination of H$_3$O$^+$,water adsorption and desorption onto dust grains, and ultraviolet photolysis ofwater and related species are found to be the three dominant processesregulating the gas-phase water abundance. While the changes are found to besignificant, we find that the effect on gas phase water abundances throughoutthe disk is short-lived (days). Even though we do not see a substantialincrease in long term water (gas and ice) production, the flares' large effectsmay be detectable as time varying inner disk water 'bursts' at radii between 5and 30 au with future far infrared observations.

Modeling Time Dependent Water Chemistry Due to Powerful X-ray Flares from T-Tauri Stars