In this paper, we propose two consistent incompressible Smoothed Particle Hydrodynamics (ISPH) methods, namely explicit ISPH (EISPH) and iterative implicit ISPH (IISPH) for simulating free surface flow as challenging complex and highly nonlinear problem. Both methods employ new consistent spatial derivatives schemes, boundary conditions free of dummy or mirror particle. In the explicit method, a projection approach is used with one pressure Poisson equation solution at each time-step. In this work, it is shown that this approach does not guarantee the incompressibility. The suggested iterative implicit approach is a remedy for this difficulty. Both methods showed satisfactory results in comparison with the available experimental and numerical solutions of the well-known 2-D dam breaking problem over dry and wet beds. However, the proposed IISPH method yields more accurate and stable results rather than EISPH even with a lower number of particles and greater time-step sizes.