A sea water system comprises, an inlet conduit assembly, a ballast tank and an overflow arrangement arranged in fluid communication with the inlet conduit assembly. The inlet conduit assembly provides a fluid communication between ambient environment and the ballast tank. A first pump assembly is arranged in the inlet conduit assembly for pumping sea water through at least a first conduit portion towards the ballast tank. A second pump assembly is arranged in fluid communication with the ballast tank and is arranged for pumping sea water from the ballast tank through an outlet conduit assembly arranged after the second pump assembly. The second pump assembly and the outlet conduit assembly are separate from the inlet conduit assembly. The sea water system may be arranged on a floating vessel.