Electrical impedance measurements have been performed on deforming fine-grained (~300 ¿m) synthetic halite rocks containing small quantities of water in order to study the evolution of fluid distribution. Experiments were carried out on four wet samples (H2O ~ 30 ppm) and one dry sample (H2O ~ 5 ppm) under nondilatant condition (125¿C, 50 MPa confining pressure, and strain rate of ~5 ¿ 10-7 s-1), using a triaxial deformation apparatus. The mechanical behavior of wet and dry samples is strikingly different. Only ~30 ppm water greatly weakens halite rocks through grain boundary migration recrystallization. Wet experiments show oscillating stress-strain curves, reflecting the competition between work hardening and weakening due to dynamic recrystallization. The dry experiment shows neither weakening nor recrystallized microstructure. The measured impedance shows that an interconnected network of water is formed even in the dry sample and that the connectivity in bulk is attained through the very thin (1--10 nm) elements of fluid. The resistivity change with deformation suggests the competition between thinning and thickening of connected fluid paths. The thinning is caused by fluid squirt due to the axial compression, and the thickening is caused by fluid squirt due to the grain growth due to fluid-assisted grain boundary migration. In wet samples the diffusivity through grain boundary water is estimated to be lower than the bulk water by 5--6 orders of magnitude. In the dry sample, grain boundary water is thinner, and its diffusivity might not be high enough to promote grain boundary migration. Observed migration recrystallization can occur in natural conditions and greatly weaken salt rocks. The impedance measurement is very useful to track the evolution of fluid distribution in deforming materials. For further understanding of mechanical and electrical properties of halite rocks it is essential to clarify properties of thin water films.