Water flood system utilizes steam to build up pressure for drive purposes and to heat the floodwater as well. A heating system on the surface provides hot flood water and additionally provides fluid-drive pressure. This system contains a boiler, a pump operated by a reciprocating direct-connected steam cylinder engine, and a heat exchanger. A steam supply line from the boiler supplies the steam engine. An exhaust steam line is connected directly to the heat exchanger. Floodwater from the pump receives heat from the exchanger before it is injected into the formation.