The infiltration of a fluid into an initially dry porous medium (e.g., a rock reservoir) is the most basic of moving boundary problems —essentially a one-phase Stefan problem in the limit of vanishing specific heat, with a latent heat equal to the porosity. The problem becomes more complex when a hydration reaction is present—imposing a transient volume sink term for the infiltrating fluid. At short times, when infiltration is much more rapid than the reaction, the in- filtration follows the basic form seen in the absence of a reaction—in one-dimension the square root of time. At intermediate times, as the reaction takes hold, the infiltration front deviates from this basic form. At large enough times, however, as the front slows, the volume over which the reaction occurs concentrates within the neighborhood of the front. This effectively reverts to a modified version of the reaction free infiltration behavior, with an effective latent heat (effective porosity) term in the ‘Stefan’ condition. Here, we will consider infiltration with hydration reactions in one-dimensional and axisymmetric domains. We will show that a numerical solution, based on a weak formulation, can recover sound predictions—recovering the expected early and late time behaviors. By contrast, a front fixing scheme, using the Landau transformation, is not able to recover late time behavior because the shrinking reaction zone can not be faithfully captured within the discretization. The problem studied has consequences for understanding reaction driven fracture—the collapse of the reaction zone corresponding to a localized eigenstrain that can initiate fracture. Understanding this phenomenon is an impor- tant step towards realizing the full potential of rock reservoirs for energy extraction and CO2 storage.