Analysis of perspective objects for construction of impervious curtains makes it possible to formulate the main features of their design and conditions for analytical solution of filtration problems. When solving the problem the hydrodynamic grid of flow movement, specific inflow of solutions, height of filtration flow before the curtain and after it are determined. The problem of laminar plane-parallel filtration of solutions with a free surface in an unpressurized reservoir through a perfect curtain of contour-linear type is solved for two flow regimes: free unpressurized and waterlogged. The equations of material balance and continuity of flow are used in the solution.