The injection into the subsoil of micro- (nZVI) and nanoparticles (nZVI) of zerovalent iron as water-based slurries for groundwater remediation is hindered by the lack of stability and mobility of both micro- and nanoscale zerovalent iron particles in water suspensions. Green polymers, such as guar gum (GG) and xanthan gum (XG) are commonly used as stabilizing agents. Water based solutions containing high concentrations of these green polymers are shear thinning fluids, presenting high viscosity in static conditions and low viscosity in dynamic conditions. This shear thinning behaviour makes the storage of iron micro- and nanoparticles more effective, providing a reduction of sedimentation and aggregation phenomena, and promotes the injection of the particle in the subsoil, avoiding high injection pressures.