Many reinforced concrete structures are exposed to outer pressure of saline water. Examples are: o Submerged tunnels o Foundations in saline groundwater o Culverts in seawater or saline groundwater o Outlet tunnels leading saline water Due to one-sided outer water pressure, salt water will penetrate the concrete by convective transport. After certain "incubation time", salt will reach the downstream surface. Water will evaporate and salt will precipitate within the downstream evaporation zone. After a certain time, when a threshold chloride concentration has been reached, corrosion will start on reinforcement located in the downstream part of the structure. The report presents a method for how to calculate the amount of chloride penetrating concrete, and the time needed for corrosion to start. Equations are given by which the calculations can be easily made when the composition of the concrete, the water permeability of concrete, the outer water pressure, and the outer salt concentration are known. In APPENDIX 1 some applications of the method are demonstrated. It is shown that the most important factors determining time to corrosion for given outer salt concentration and water pressure are: o Water permeability of concrete o Chloride binding capacity of concrete o Thickness of concrete member In APPENDIX 2 values are given for the chloride content in seawater around the Scandinavian coast. In APPENDIX 3 the permeability of concrete to water under one-sided pressure is discussed. Data from literature are given.