Lin and Lin (Faulty assumptions: Groundwater modeling through anisotropic fault zones, Journal of Hydrology 653(2025)) make unfounded claims about earlier studies of fault aquifer interaction: they state that the standard boundary conditions for a conductive fault used in earlier studies are flawed or based on faulty assumptions and that the earlier studies did not consider the discontinuities in both the normal component of flow and hydraulic head across a general fault. Further, they are unclear about the approximations in their own analysis which attempts to replace the two-dimensional flow field within a thin, anisotropic fault zone with two, one-dimensional, internal boundary conditions. Their claims about earlier studies are refuted and the approximations in their analysis are examined. Despite the limitations of their analysis, the work of Lin and Lin has value.

Deformations of the earth’s crust create tortuous paths for groundwater flow, altering pressure distributions and flow lines. A solution for steady groundwater flow through a deformed aquifer is derived by applying the singular point method using a rectangular reference plane. The singular point method is used to develop conformal mappings with complex geometries using basic principles of groundwater mechanics including superposition, the method of images, and stagnation point analysis. The derived solution contains three parameters that can be chosen to simulate flow through a variety of deformed aquifers, including flow through a normal fault with a 90^∘ dip, flow through a fold, and flow through a relay ramp.